{"id":14958,"date":"2026-07-10T05:55:07","date_gmt":"2026-07-09T20:55:07","guid":{"rendered":"https:\/\/genai-ai.co.jp\/ai-kanri\/?p=14958"},"modified":"2026-07-10T05:55:08","modified_gmt":"2026-07-09T20:55:08","slug":"cc-java-string-compare","status":"publish","type":"post","link":"https:\/\/genai-ai.co.jp\/ai-kanri\/blog\/cc-java-string-compare\/","title":{"rendered":"\u30102026\u5e747\u6708\u6700\u65b0\u3011Java\u306eString\u6bd4\u8f03\u3092\u5b8c\u5168\u89e3\u8aac\uff01\u300c==\u300d\u3068\u300cequals\u300d\u306e\u9055\u3044\u30fbnull\u306e\u7f60\u30fbClaude Code\u3067\u5373\u89e3\u6c7a\u3059\u308b\u65b9\u6cd5"},"content":{"rendered":"\n<style>\n.g-flow-row{display:flex;gap:8px;justify-content:center;flex-wrap:wrap;align-items:center;}\n.g-flow-item{background:linear-gradient(135deg,#1a1a1a,#2a1015);color:#fff;border-radius:8px;padding:16px 14px;min-width:130px;flex:1;text-align:center;}\n.g-flow-arrow{color:#dc2626;font-size:20px;font-weight:700;}\n.g-card-row{display:flex;gap:12px;flex-wrap:wrap;margin:0 0 32px;}\n.g-card-row>div{flex:1;min-width:220px;}\n@media(max-width:600px){\n  .g-flow-row{flex-direction:column;}\n  .g-flow-arrow{transform:rotate(90deg);}\n  .g-card-row{flex-direction:column;}\n  .g-card-row>div{min-width:100%;}\n}\n<\/style>\n\n\n\n<div style=\"margin:0 0 32px;\">\n  <img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/07\/thumb-cc-java-string-compare-1.jpg\" alt=\"\u30102026\u5e747\u6708\u6700\u65b0\u3011Java\u306eString\u6bd4\u8f03\u3092\u5b8c\u5168\u89e3\u8aac\uff01\u300c==\u300d\u3068\u300cequals\u300d\u306e\u9055\u3044\u30fbnull\u306e\u7f60\u30fbClaude Code\u3067\u5373\u89e3\u6c7a\u3059\u308b\u65b9\u6cd5\" style=\"width:100%;height:auto;border-radius:12px;display:block;\">\n<\/div>\n\n\n\n<div style=\"background:#f8f9fa;border-radius:12px;padding:24px 28px;margin:0 0 32px;border-left:4px solid #dc2626;\">\n  <p style=\"font-size:15px;font-weight:700;color:#1a1a1a;margin:0 0 16px;\">\u3053\u306e\u8a18\u4e8b\u306e\u5185\u5bb9<\/p>\n  <ol style=\"margin:0;padding-left:20px;font-size:14px;line-height:2.2;list-style:none;\">\n    <li><a href=\"#sec-01\" style=\"color:#495057;text-decoration:none;\"><span style=\"color:#dc2626;font-weight:700;margin-right:8px;\">01<\/span>Java\u306eString\u6bd4\u8f03\u306e\u57fa\u672c\uff1a\u300c==\u300d\u3068\u300cequals()\u300d\u306e\u672c\u8cea\u7684\u306a\u9055\u3044<\/a><\/li>\n    <li><a href=\"#sec-02\" style=\"color:#495057;text-decoration:none;\"><span style=\"color:#dc2626;font-weight:700;margin-right:8px;\">02<\/span>equals()\u306e\u6b63\u3057\u3044\u4f7f\u3044\u65b9\u3068\u5fdc\u7528<\/a><\/li>\n    <li><a href=\"#sec-03\" style=\"color:#495057;text-decoration:none;\"><span style=\"color:#dc2626;font-weight:700;margin-right:8px;\">03<\/span>null\u3068\u306e\u6bd4\u8f03\uff1aNullPointerException\u3092\u9632\u3050\u65b9\u6cd5<\/a><\/li>\n    <li><a href=\"#sec-04\" style=\"color:#495057;text-decoration:none;\"><span style=\"color:#dc2626;font-weight:700;margin-right:8px;\">04<\/span>\u305d\u306e\u4ed6\u306eString\u6bd4\u8f03\u30e1\u30bd\u30c3\u30c9\u5b8c\u5168\u89e3\u8aac<\/a><\/li>\n    <li><a href=\"#sec-05\" style=\"color:#495057;text-decoration:none;\"><span style=\"color:#dc2626;font-weight:700;margin-right:8px;\">05<\/span>\u3088\u304f\u3042\u308b\u30d0\u30b0\u30d1\u30bf\u30fc\u30f310\u9078\u3068\u305d\u306e\u4fee\u6b63\u65b9\u6cd5<\/a><\/li>\n    <li><a href=\"#sec-06\" style=\"color:#495057;text-decoration:none;\"><span style=\"color:#dc2626;font-weight:700;margin-right:8px;\">06<\/span>Claude Code\u3067Java\u306eString\u6bd4\u8f03\u30d0\u30b0\u3092\u5373\u89e3\u6c7a\u3059\u308b\u65b9\u6cd5<\/a><\/li>\n    <li><a href=\"#faq\" style=\"color:#495057;text-decoration:none;\"><span style=\"color:#dc2626;font-weight:700;margin-right:8px;\">FAQ<\/span>\u3088\u304f\u3042\u308b\u8cea\u554f<\/a><\/li>\n  <\/ol>\n<\/div>\n\n\n\n<p class=\"wp-block-paragraph\">Java\u3067String\u3092\u6bd4\u8f03\u3059\u308b\u3068\u304d\u3001\u300c<code>==<\/code>\u3067\u6bd4\u8f03\u3057\u305f\u3089\u540c\u3058\u6587\u5b57\u5217\u306a\u306e\u306bfalse\u306b\u306a\u3063\u305f\u300d\u300c<code>equals()<\/code>\u3067\u6bd4\u8f03\u3057\u305f\u3089NullPointerException\u304c\u51fa\u305f\u300d\u2014\u2014\u3053\u3046\u3057\u305f\u843d\u3068\u3057\u7a74\u3067\u30cf\u30de\u308b\u30a8\u30f3\u30b8\u30cb\u30a2\u304c\u5f8c\u3092\u7d76\u3061\u307e\u305b\u3093\u3002\u672c\u8a18\u4e8b\u3067\u306f<strong>Java\u306eString\u6bd4\u8f03\u3067\u7d76\u5bfe\u306b\u62bc\u3055\u3048\u308b\u3079\u304d\u5168\u624b\u6cd5<\/strong>\u3092\u3001\u5b9f\u969b\u306e\u30b3\u30fc\u30c9\u4f8b\u30fb\u3088\u304f\u3042\u308b\u30d0\u30b0\u30d1\u30bf\u30fc\u30f3\u30fb\u4fee\u6b63\u65b9\u6cd5\u307e\u3067\u542b\u3081\u3066\u5b8c\u5168\u89e3\u8aac\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<p class=\"wp-block-paragraph\">\u307e\u305f\u5f8c\u534a\u3067\u306f\u3001<strong>Claude Code\u3092\u4f7f\u3063\u3066Java\u306e\u30d0\u30b0\u3092\u77ac\u6642\u306b\u8a3a\u65ad\u30fb\u4fee\u6b63\u3059\u308b\u65b9\u6cd5<\/strong>\u3082\u7d39\u4ecb\u3057\u307e\u3059\u3002\u300cequals()\u3068null\u306e\u7d44\u307f\u5408\u308f\u305b\u304c\u8907\u96d1\u3067\u308f\u304b\u3089\u306a\u3044\u300d\u300c\u65e2\u5b58\u306eJava\u30b3\u30fc\u30c9\u306e\u30d0\u30b0\u3092\u52b9\u7387\u3088\u304f\u76f4\u3057\u305f\u3044\u300d\u3068\u3044\u3046\u65b9\u306f\u3001\u305c\u3072\u6700\u5f8c\u307e\u3067\u304a\u8aad\u307f\u304f\u3060\u3055\u3044\u3002<\/p>\n\n\n\n<div class=\"balloon-wrap\">\n  <div class=\"balloon-icon\">\n    <img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/04\/ceo-sugasawa.jpg\" alt=\"\u4ee3\u8868\u83c5\u6fa4\">\n    <span class=\"balloon-name\">\u4ee3\u8868\u83c5\u6fa4<\/span>\n  <\/div>\n  <div class=\"balloon-body\">Java\u3092\u4f7f\u3063\u3066\u3044\u308b\u4f01\u696d\u306e\u30b7\u30b9\u30c6\u30e0\u62c5\u5f53\u8005\u304b\u3089\u300c==\u3068equals()\u306e\u9055\u3044\u304c\u308f\u304b\u3089\u306a\u304f\u3066\u30d0\u30b0\u304c\u51fa\u305f\u300d\u3068\u3044\u3046\u76f8\u8ac7\u3092\u53d7\u3051\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u306e\u554f\u984c\u306fJava\u306e\u6839\u672c\u7684\u306a\u8a2d\u8a08\u601d\u60f3\u306b\u8d77\u56e0\u3059\u308b\u3082\u306e\u3067\u3001\u7406\u89e3\u3055\u3048\u3059\u308c\u3070\u4e8c\u5ea6\u3068\u30cf\u30de\u308a\u307e\u305b\u3093\u3002\u3053\u306e\u8a18\u4e8b\u3067\u4e00\u5ea6\u3057\u3063\u304b\u308a\u7406\u89e3\u3057\u3066\u304a\u304f\u3053\u3068\u3092\u5f37\u304f\u304a\u52e7\u3081\u3057\u307e\u3059\u3002<\/div>\n<\/div>\n\n\n\n<div class=\"balloon-wrap is-right\">\n  <div class=\"balloon-icon\">\n    <img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/04\/yamazaki-avatar.png\" alt=\"AI\u9b3c\u7ba1\u7406\u5c71\u5d0e\">\n    <span class=\"balloon-name\">AI\u9b3c\u7ba1\u7406\u5c71\u5d0e<\/span>\n  <\/div>\n  <div class=\"balloon-body\">Java\u306eString\u6bd4\u8f03\u306e\u554f\u984c\u306f\u3001\u975e\u30a8\u30f3\u30b8\u30cb\u30a2\u306e\u65b9\u306b\u306f\u300c\u306a\u305c\u305d\u3093\u306a\u306b\u8907\u96d1\u306a\u306e\uff1f\u300d\u3068\u601d\u308f\u308c\u308b\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u3002\u7406\u7531\u306fJava\u304c\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u6307\u5411\u8a00\u8a9e\u3067\u3042\u308a\u3001\u300c\u6587\u5b57\u5217\u306e\u4e2d\u8eab\u300d\u3068\u300c\u6587\u5b57\u5217\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30a2\u30c9\u30ec\u30b9\uff08\u5834\u6240\uff09\u300d\u306e2\u7a2e\u985e\u3092\u6bd4\u8f03\u3067\u304d\u308b\u305f\u3081\u3002\u3053\u306e\u8a18\u4e8b\u3067\u4e21\u8005\u306e\u9055\u3044\u3092\u7406\u89e3\u3059\u308c\u3070\u3001\u5f8c\u306f\u30b7\u30f3\u30d7\u30eb\u306b\u300c\u6587\u5b57\u5217\u306e\u6bd4\u8f03\u306b\u306fequals()\u3092\u4f7f\u3046\u300d\u3068\u3044\u3046\u30eb\u30fc\u30eb\u3067\u89e3\u6c7a\u3067\u304d\u307e\u3059\u3002<\/div>\n<\/div>\n\n\n\n<div style=\"background:#fafafa;border-radius:8px;padding:16px 20px;margin:16px 0;border-left:4px solid #dc2626;\">\n<div style=\"display:flex;align-items:flex-start;gap:8px;padding:6px 0;font-size:15px;line-height:1.6;\"><span style=\"color:#dc2626;font-size:16px;flex-shrink:0;margin-top:2px;\">&#10004;&#65039;<\/span><span><strong>==\u3068equals()\u306e\u672c\u8cea\u7684\u306a\u9055\u3044<\/strong>\uff08\u53c2\u7167\u6bd4\u8f03\u3068\u5024\u6bd4\u8f03\uff09\u304c\u5b8c\u5168\u306b\u7406\u89e3\u3067\u304d\u308b<\/span><\/div>\n<div style=\"display:flex;align-items:flex-start;gap:8px;padding:6px 0;font-size:15px;line-height:1.6;\"><span style=\"color:#dc2626;font-size:16px;flex-shrink:0;margin-top:2px;\">&#10004;&#65039;<\/span><span><strong>NullPointerException\u3092\u9632\u3050<\/strong>\u5b89\u5168\u306aString\u6bd4\u8f03\u30d1\u30bf\u30fc\u30f3\u304c\u308f\u304b\u308b<\/span><\/div>\n<div style=\"display:flex;align-items:flex-start;gap:8px;padding:6px 0;font-size:15px;line-height:1.6;\"><span style=\"color:#dc2626;font-size:16px;flex-shrink:0;margin-top:2px;\">&#10004;&#65039;<\/span><span><strong>Objects.equals\u30fbequalsIgnoreCase\u30fbcompareTo<\/strong>\u7b49\u306e\u4f7f\u3044\u5206\u3051\u304c\u660e\u78ba\u306b\u306a\u308b<\/span><\/div>\n<div style=\"display:flex;align-items:flex-start;gap:8px;padding:6px 0;font-size:15px;line-height:1.6;\"><span style=\"color:#dc2626;font-size:16px;flex-shrink:0;margin-top:2px;\">&#10004;&#65039;<\/span><span><strong>\u3088\u304f\u3042\u308b\u30d0\u30b0\u30d1\u30bf\u30fc\u30f310\u9078<\/strong>\u3068\u5373\u4fee\u6b63\u3067\u304d\u308b\u6b63\u3057\u3044\u30b3\u30fc\u30c9\u304c\u78ba\u8a8d\u3067\u304d\u308b<\/span><\/div>\n<div style=\"display:flex;align-items:flex-start;gap:8px;padding:6px 0;font-size:15px;line-height:1.6;\"><span style=\"color:#dc2626;font-size:16px;flex-shrink:0;margin-top:2px;\">&#10004;&#65039;<\/span><span><strong>Claude Code\u3092\u4f7f\u3063\u305fJava\u30d0\u30b0\u306e\u5373\u8a3a\u65ad\u30fb\u4fee\u6b63<\/strong>\u65b9\u6cd5\u304c\u308f\u304b\u308b<\/span><\/div>\n<\/div>\n\n\n<div style=\"margin:48px 0 8px;display:flex;gap:12px;justify-content:center;flex-wrap:wrap;\"><a href=\"https:\/\/aikanri.genai-ai.co.jp\/seminar2-blog\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_content=cc-java-string-compare&#038;blog_slug=cc-java-string-compare\" target=\"_blank\" rel=\"noopener\" aria-label=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff08\u7121\u6599\u30fb1on1\u30fb60\u5206\uff09\u306e\u4e88\u7d04\u753b\u9762\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_seminar_claude_code_2026.jpg\" alt=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff5c\u7d4c\u55b6\u8005\u30fb\u4f1a\u793e\u5f79\u54e1\u5c02\u7528 1on1 60\u5206 \u7121\u6599\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><a href=\"https:\/\/aikanri.genai-ai.co.jp\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_campaign=cc-java-string-compare&#038;utm_content=h2-banner-kanri\" target=\"_blank\" rel=\"noopener\" aria-label=\"AI\u9b3c\u7ba1\u7406 \u516c\u5f0f\u30b5\u30a4\u30c8\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_blog_1to1.jpg\" alt=\"Claude Code\u3092\u7d4c\u55b6\u306b\u6d3b\u304b\u3057\u305f\u3044\u65b9\u3078 \u2014 AI\u9b3c\u7ba1\u7406\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><\/div>\n\n\n<div id=\"sec-01\"><\/div>\n<h2 class=\"section-header-img\" style=\"margin:32px 0 24px;border-radius:8px;overflow:hidden;background:linear-gradient(135deg,#1a1a1a 0%,#2a1015 100%);padding:32px 28px;color:#fff;position:relative;border:none;border-left:none;text-align:left;\">\n  <span class=\"section-number\" style=\"display:block;\">01<\/span>\n  <span class=\"section-label\" style=\"display:block;\">BASICS<\/span>\n  <span class=\"section-title\" style=\"display:block;\">Java\u306eString\u6bd4\u8f03\u306e\u57fa\u672c\uff1a\u300c==\u300d\u3068\u300cequals()\u300d\u306e\u672c\u8cea\u7684\u306a\u9055\u3044<\/span>\n  <span class=\"section-desc\">\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30a2\u30c9\u30ec\u30b9\u3068\u4e2d\u8eab\u3001\u4f55\u304c\u9055\u3046\u306e\u304b<\/span>\n<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Java\u3067String\uff08\u6587\u5b57\u5217\uff09\u3092\u6bd4\u8f03\u3059\u308b\u65b9\u6cd5\u306f\u8907\u6570\u3042\u308a\u307e\u3059\u304c\u3001\u6700\u3082\u91cd\u8981\u3067\u3001\u6700\u3082\u6df7\u4e71\u3092\u751f\u3080\u7d44\u307f\u5408\u308f\u305b\u304c\u300c<code>==<\/code>\u6f14\u7b97\u5b50\u300d\u3068\u300c<code>equals()<\/code>\u30e1\u30bd\u30c3\u30c9\u300d\u3067\u3059\u3002\u3053\u306e2\u3064\u306e\u672c\u8cea\u7684\u306a\u9055\u3044\u3092\u7406\u89e3\u3059\u308b\u3053\u3068\u304c\u3001Java\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u91cd\u8981\u306a\u57fa\u790e\u306e\u4e00\u3064\u3067\u3059\u3002<\/p>\n\n\n\n<div style=\"background:#f8f9fa;border-left:4px solid #6b7280;border-radius:0 8px 8px 0;padding:16px 20px;margin:20px 0;\">\n  <p style=\"margin:0 0 4px;font-size:13px;font-weight:700;color:#6b7280;letter-spacing:1px;\">&#128218; \u7528\u8a9e\u89e3\u8aac<\/p>\n  <p style=\"margin:0;font-size:15px;line-height:1.7;\"><strong>\u53c2\u7167\u578b\uff08Reference Type\uff09<\/strong>\uff1aJava\u306e\u30c7\u30fc\u30bf\u578b\u306b\u306f\u300c\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u578b\uff08int\u30fbboolean\u30fbchar\u7b49\uff09\u300d\u3068\u300c\u53c2\u7167\u578b\uff08\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u578b\uff09\u300d\u304c\u3042\u308b\u3002\u53c2\u7167\u578b\u306e\u5909\u6570\u306f\u5024\u305d\u306e\u3082\u306e\u3092\u4fdd\u6301\u3059\u308b\u306e\u3067\u306f\u306a\u304f\u3001\u5024\u304c\u683c\u7d0d\u3055\u308c\u305f\u30e1\u30e2\u30ea\u4e0a\u306e\u300c\u4f4f\u6240\uff08\u53c2\u7167\u5148\u306e\u30a2\u30c9\u30ec\u30b9\uff09\u300d\u3092\u4fdd\u6301\u3059\u308b\u3002String\u306f\u30af\u30e9\u30b9\uff08\u53c2\u7167\u578b\uff09\u3067\u3042\u308a\u3001\u5909\u6570str\u306f\u6587\u5b57\u5217\u306e\u5185\u5bb9\u305d\u306e\u3082\u306e\u3067\u306f\u306a\u304f\u3001\u6587\u5b57\u5217\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304c\u5b58\u5728\u3059\u308b\u30e1\u30e2\u30ea\u30a2\u30c9\u30ec\u30b9\u3092\u6307\u3057\u3066\u3044\u308b\u3002<\/p>\n<\/div>\n\n\n\n<h3 class=\"wp-block-heading\">\u300c==\u300d\u6f14\u7b97\u5b50\u304c\u6bd4\u8f03\u3059\u308b\u3082\u306e<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Java\u306e<code>==<\/code>\u6f14\u7b97\u5b50\u306f\u3001\u300c2\u3064\u306e\u5909\u6570\u304c\u540c\u3058\u30e1\u30e2\u30ea\u4e0a\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u6307\u3057\u3066\u3044\u308b\u304b\u300d\uff08\u53c2\u7167\u306e\u6bd4\u8f03\uff09\u3092\u78ba\u8a8d\u3057\u307e\u3059\u3002\u3064\u307e\u308a\u300c\u4f4f\u6240\u304c\u540c\u3058\u304b\u3069\u3046\u304b\u300d\u3092\u898b\u308b\u305f\u3081\u3001\u4e2d\u8eab\u306e\u6587\u5b57\u5217\u304c\u540c\u3058\u3067\u3082\u3001\u7570\u306a\u308b\u5834\u6240\u306b\u5b58\u5728\u3059\u308b\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3067\u3042\u308c\u3070<code>false<\/code>\u3092\u8fd4\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">String a = new String(\"hello\");\nString b = new String(\"hello\");\n\nSystem.out.println(a == b);      \/\/ false\uff08\u5225\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8=\u4f4f\u6240\u304c\u9055\u3046\uff09\nSystem.out.println(a.equals(b)); \/\/ true\uff08\u4e2d\u8eab\u306e\u6587\u5b57\u5217\u306f\u540c\u3058\uff09<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e0a\u8a18\u306e\u4f8b\u3067\u306f<code>a<\/code>\u3068<code>b<\/code>\u306f\u5171\u306b<code>\"hello\"<\/code>\u3068\u3044\u3046\u5185\u5bb9\u3092\u6301\u3063\u3066\u3044\u307e\u3059\u304c\u3001<code>new String()<\/code>\u3067\u5225\u3005\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3068\u3057\u3066\u751f\u6210\u3055\u308c\u3066\u3044\u308b\u305f\u3081\u3001<code>==<\/code>\u6bd4\u8f03\u3067\u306f<code>false<\/code>\u306b\u306a\u308a\u307e\u3059\u3002\u3053\u308c\u304cJava\u306e<code>==<\/code>\u6f14\u7b97\u5b50\u306e\u843d\u3068\u3057\u7a74\u3067\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">String\u5b9a\u6570\u30d7\u30fc\u30eb\u3068\u300c==\u300d\u304c\u610f\u56f3\u305b\u305a\u52d5\u304f\u843d\u3068\u3057\u7a74<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Java\u306b\u306f\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u6700\u9069\u5316\u306e\u305f\u3081\u306e\u300cString\u5b9a\u6570\u30d7\u30fc\u30eb\uff08String Pool\uff09\u300d\u3068\u3044\u3046\u4ed5\u7d44\u307f\u304c\u3042\u308a\u307e\u3059\u3002\u6587\u5b57\u5217\u30ea\u30c6\u30e9\u30eb\uff08\u30c0\u30d6\u30eb\u30af\u30a9\u30fc\u30c8\u3067\u56f2\u3093\u3060\u6587\u5b57\u5217\uff09\u306f\u3001\u3053\u306e\u5b9a\u6570\u30d7\u30fc\u30eb\u306b\u683c\u7d0d\u3055\u308c\u307e\u3059\u3002\u540c\u3058\u30ea\u30c6\u30e9\u30eb\u306f\u540c\u3058\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u518d\u5229\u7528\u3059\u308b\u305f\u3081\u3001<code>==<\/code>\u304c\u5076\u7136<code>true<\/code>\u3092\u8fd4\u3059\u5834\u5408\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">String a = \"hello\";   \/\/ \u5b9a\u6570\u30d7\u30fc\u30eb\u306b\u683c\u7d0d\nString b = \"hello\";   \/\/ \u540c\u3058\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u518d\u5229\u7528\n\nSystem.out.println(a == b); \/\/ true\uff08\u5076\u7136\u540c\u3058\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\uff09\n\n\/\/ \u3057\u304b\u3057\u3001\u5916\u90e8\u5165\u529b\u3084\u52d5\u7684\u306b\u751f\u6210\u3057\u305f\u5834\u5408\u306f\u5225\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u306a\u308b\nString c = new String(\"hello\");\nSystem.out.println(a == c); \/\/ false\uff08\u5225\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\uff09<\/code><\/pre>\n\n\n\n<div style=\"background:#fef2f2;border:2px solid #dc2626;border-radius:8px;padding:20px 24px;margin:24px 0;\">\n  <div style=\"display:flex;align-items:center;gap:8px;margin-bottom:12px;\">\n    <span style=\"font-size:20px;\">&#9888;&#65039;<\/span>\n    <strong style=\"color:#dc2626;font-size:16px;\">\u300c==\u3067true\u306b\u306a\u3063\u305f\u300d\u306f\u5b89\u5168\u3068\u306f\u8a00\u3048\u306a\u3044<\/strong>\n  <\/div>\n  <p style=\"margin:0;font-size:15px;line-height:1.8;color:#333;\">\u5b9a\u6570\u30d7\u30fc\u30eb\u306e\u4ed5\u7d44\u307f\u306b\u3088\u308a\u300c\u540c\u3058\u6587\u5b57\u5217\u30ea\u30c6\u30e9\u30eb\u306a\u3089==\u3067true\u306b\u306a\u308b\u300d\u30b1\u30fc\u30b9\u304c\u3042\u308a\u307e\u3059\u3002\u3057\u304b\u3057\u3053\u306e\u52d5\u4f5c\u306b\u4f9d\u5b58\u3057\u305f\u30b3\u30fc\u30c9\u306f\u3001\u30e6\u30fc\u30b6\u30fc\u5165\u529b\u30fb\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u53d6\u5f97\u30fb\u5916\u90e8API\u304b\u3089\u53d7\u3051\u53d6\u3063\u305f\u6587\u5b57\u5217\u3067\u306e\u6bd4\u8f03\u3067\u306f\u5fc5\u305afalse\u306b\u306a\u308a\u30d0\u30b0\u304c\u767a\u751f\u3057\u307e\u3059\u3002\u6587\u5b57\u5217\u306e\u6bd4\u8f03\u306b\u306f\u5e38\u306bequals()\u3092\u4f7f\u3046\u7fd2\u6163\u3092\u3064\u3051\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n<\/div>\n\n\n\n<div class=\"balloon-wrap\">\n  <div class=\"balloon-icon\">\n    <img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/04\/ceo-sugasawa.jpg\" alt=\"\u4ee3\u8868\u83c5\u6fa4\">\n    <span class=\"balloon-name\">\u4ee3\u8868\u83c5\u6fa4<\/span>\n  <\/div>\n  <div class=\"balloon-body\">String\u5b9a\u6570\u30d7\u30fc\u30eb\u306e\u4ed5\u7d44\u307f\u3092\u77e5\u3089\u305a\u306b==\u3067\u6587\u5b57\u5217\u6bd4\u8f03\u3057\u3066\u3044\u305f\u30b3\u30fc\u30c9\u304c\u3001\u300c\u958b\u767a\u74b0\u5883\u3067\u306f\u52d5\u3044\u305f\u306e\u306b\u672c\u756a\u3067\u30d0\u30b0\u304c\u51fa\u305f\u300d\u3068\u3044\u3046\u4e8b\u4f8b\u306f\u983b\u7e41\u306b\u3042\u308a\u307e\u3059\u3002\u5358\u4f53\u30c6\u30b9\u30c8\u3067\u306f\u56fa\u5b9a\u6587\u5b57\u5217\u3092\u4f7f\u3046\u305f\u3081==\u304c\u901a\u3063\u3066\u3082\u3001\u5b9f\u969b\u306e\u904b\u7528\u3067\u306f\u30e6\u30fc\u30b6\u30fc\u304c\u5165\u529b\u3057\u305f\u6587\u5b57\u5217\u304c\u5225\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u306a\u308b\u304b\u3089\u3067\u3059\u3002<\/div>\n<\/div>\n\n\n<div style=\"margin:48px 0 8px;display:flex;gap:12px;justify-content:center;flex-wrap:wrap;\"><a href=\"https:\/\/aikanri.genai-ai.co.jp\/seminar2-blog\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_content=cc-java-string-compare&#038;blog_slug=cc-java-string-compare\" target=\"_blank\" rel=\"noopener\" aria-label=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff08\u7121\u6599\u30fb1on1\u30fb60\u5206\uff09\u306e\u4e88\u7d04\u753b\u9762\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_seminar_claude_code_2026.jpg\" alt=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff5c\u7d4c\u55b6\u8005\u30fb\u4f1a\u793e\u5f79\u54e1\u5c02\u7528 1on1 60\u5206 \u7121\u6599\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><a href=\"https:\/\/aikanri.genai-ai.co.jp\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_campaign=cc-java-string-compare&#038;utm_content=h2-banner-kanri\" target=\"_blank\" rel=\"noopener\" aria-label=\"AI\u9b3c\u7ba1\u7406 \u516c\u5f0f\u30b5\u30a4\u30c8\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_blog_1to1.jpg\" alt=\"Claude Code\u3092\u7d4c\u55b6\u306b\u6d3b\u304b\u3057\u305f\u3044\u65b9\u3078 \u2014 AI\u9b3c\u7ba1\u7406\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><\/div>\n\n\n<div id=\"sec-02\"><\/div>\n<h2 class=\"section-header-img\" style=\"margin:32px 0 24px;border-radius:8px;overflow:hidden;background:linear-gradient(135deg,#1a1a1a 0%,#2a1015 100%);padding:32px 28px;color:#fff;position:relative;border:none;border-left:none;text-align:left;\">\n  <span class=\"section-number\" style=\"display:block;\">02<\/span>\n  <span class=\"section-label\" style=\"display:block;\">EQUALS<\/span>\n  <span class=\"section-title\" style=\"display:block;\">equals()\u306e\u6b63\u3057\u3044\u4f7f\u3044\u65b9\u3068\u5fdc\u7528<\/span>\n  <span class=\"section-desc\">\u57fa\u672c\u30fbequalsIgnoreCase\u30fb\u6bd4\u8f03\u306e\u5411\u304d\u306e\u6ce8\u610f\u70b9<\/span>\n<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\"><code>String.equals()<\/code>\u306f\u6587\u5b57\u5217\u306e\u300c\u5185\u5bb9\uff08\u5024\uff09\u300d\u3092\u6bd4\u8f03\u3057\u307e\u3059\u3002\u5927\u6587\u5b57\u5c0f\u6587\u5b57\u3092\u533a\u5225\u3057\u3066\u5b8c\u5168\u4e00\u81f4\u3059\u308b\u5834\u5408\u306b<code>true<\/code>\u3092\u8fd4\u3057\u307e\u3059\u3002Java\u3067\u306e\u6587\u5b57\u5217\u6bd4\u8f03\u306e\u57fa\u672c\u4e2d\u306e\u57fa\u672c\u3067\u3042\u308a\u3001\u6700\u3082\u591a\u304f\u4f7f\u308f\u308c\u308b\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u3002<\/p>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">String str1 = \"Hello\";\nString str2 = \"Hello\";\nString str3 = \"hello\";\n\nSystem.out.println(str1.equals(str2)); \/\/ true\uff08\u5b8c\u5168\u4e00\u81f4\uff09\nSystem.out.println(str1.equals(str3)); \/\/ false\uff08\u5927\u6587\u5b57\u5c0f\u6587\u5b57\u304c\u9055\u3046\uff09\nSystem.out.println(str1.equals(\"Hello\")); \/\/ true\uff08\u30ea\u30c6\u30e9\u30eb\u3068\u3082\u6bd4\u8f03\u53ef\uff09<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">equalsIgnoreCase()\uff1a\u5927\u6587\u5b57\u5c0f\u6587\u5b57\u3092\u7121\u8996\u3057\u3066\u6bd4\u8f03<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u30e6\u30fc\u30b6\u30fc\u5165\u529b\u3084\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u30fb\u30b3\u30de\u30f3\u30c9\u306a\u3069\u3001\u5927\u6587\u5b57\u5c0f\u6587\u5b57\u3092\u533a\u5225\u305b\u305a\u306b\u6bd4\u8f03\u3057\u305f\u3044\u5834\u5408\u306f<code>equalsIgnoreCase()<\/code>\u3092\u4f7f\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">String input = \"YES\";\nString expected = \"yes\";\n\nSystem.out.println(input.equalsIgnoreCase(expected)); \/\/ true\nSystem.out.println(input.equals(expected));           \/\/ false\n\n\/\/ \u6d3b\u7528\u4f8b\uff1a\u30e6\u30fc\u30b6\u30fc\u30b3\u30de\u30f3\u30c9\u306e\u6bd4\u8f03\nString command = userInput.trim();\nif (command.equalsIgnoreCase(\"quit\")) {\n    System.out.println(\"\u7d42\u4e86\u3057\u307e\u3059\");\n}<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u6bd4\u8f03\u306e\u5411\u304d\uff1a\u300c\u5b9a\u6570.equals(\u5909\u6570)\u300d\u30d1\u30bf\u30fc\u30f3\u304c\u5b89\u5168<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">equals()\u3092\u4f7f\u3046\u969b\u3001<code>str.equals(\"\u5b9a\u6570\")<\/code>\uff08\u5909\u6570.equals(\u5b9a\u6570)\uff09\u3067\u306f\u306a\u304f\u3001<code>\"\u5b9a\u6570\".equals(str)<\/code>\uff08\u5b9a\u6570.equals(\u5909\u6570)\uff09\u3068\u3044\u3046\u5f62\u3067\u66f8\u304f\u3068\u3001<code>str<\/code>\u304c<code>null<\/code>\u306e\u5834\u5408\u306eNullPointerException\u3092\u9632\u3052\u307e\u3059\u3002\u3053\u308c\u306fJava\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u306e\u5b9a\u756a\u30d1\u30bf\u30fc\u30f3\u3067\u3059\u3002<\/p>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">String status = getStatusFromDatabase(); \/\/ null\u304c\u8fd4\u308b\u53ef\u80fd\u6027\u3042\u308a\n\n\/\/ \u5371\u967a\u306a\u30d1\u30bf\u30fc\u30f3\uff08status\u304cnull\u3060\u3068NullPointerException\uff09\nif (status.equals(\"active\")) { ... }\n\n\/\/ \u5b89\u5168\u306a\u30d1\u30bf\u30fc\u30f3\uff08\u5b9a\u6570\u3092\u5de6\u5074\u306b\u7f6e\u304f\uff09\nif (\"active\".equals(status)) { ... } \/\/ status\u304cnull\u3067\u3082false\u3092\u8fd4\u3059<\/code><\/pre>\n\n\n\n<div style=\"background:#f8f9fa;border-left:4px solid #6b7280;border-radius:0 8px 8px 0;padding:16px 20px;margin:20px 0;\">\n  <p style=\"margin:0 0 4px;font-size:13px;font-weight:700;color:#6b7280;letter-spacing:1px;\">&#128218; \u7528\u8a9e\u89e3\u8aac<\/p>\n  <p style=\"margin:0;font-size:15px;line-height:1.7;\"><strong>NullPointerException<\/strong>\uff1aJava\u3067\u6700\u3082\u983b\u7e41\u306b\u767a\u751f\u3059\u308b\u5b9f\u884c\u6642\u4f8b\u5916\uff08Runtime Exception\uff09\u306e\u4e00\u3064\u3002null\uff08\u5024\u306a\u3057\uff09\u306e\u72b6\u614b\u306e\u5909\u6570\u306b\u5bfe\u3057\u3066\u30e1\u30bd\u30c3\u30c9\u3092\u547c\u3073\u51fa\u3057\u305f\u308a\u3001\u30d5\u30a3\u30fc\u30eb\u30c9\u306b\u30a2\u30af\u30bb\u30b9\u3057\u3088\u3046\u3068\u3057\u305f\u3068\u304d\u306b\u767a\u751f\u3059\u308b\u3002\u300cstr.equals(\"hello\")\u300d\u306estr\u304cnull\u3060\u3068\u767a\u751f\u3059\u308b\u3002\u30d7\u30ed\u30b0\u30e9\u30e0\u304c\u30af\u30e9\u30c3\u30b7\u30e5\u3059\u308b\u539f\u56e0\u306b\u306a\u308b\u305f\u3081\u3001null\u5b89\u5168\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u7fd2\u6163\u304c\u91cd\u8981\u3002\u7565\u3057\u3066NPE\u3068\u547c\u3070\u308c\u308b\u3053\u3068\u3082\u591a\u3044\u3002<\/p>\n<\/div>\n\n\n\n<div class=\"balloon-wrap is-right\">\n  <div class=\"balloon-icon\">\n    <img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/04\/yamazaki-avatar.png\" alt=\"AI\u9b3c\u7ba1\u7406\u5c71\u5d0e\">\n    <span class=\"balloon-name\">AI\u9b3c\u7ba1\u7406\u5c71\u5d0e<\/span>\n  <\/div>\n  <div class=\"balloon-body\">\u300c\u5b9a\u6570.equals(\u5909\u6570)\u300d\u30d1\u30bf\u30fc\u30f3\u306fYoda\u8a18\u6cd5\uff08\u30e8\u30fc\u30c0\u8a18\u6cd5\uff09\u3068\u3082\u547c\u3070\u308c\u307e\u3059\u3002Starwars\u306e\u30e8\u30fc\u30c0\u30ad\u30e3\u30e9\u30af\u30bf\u30fc\u306e\u3088\u3046\u306a\u300c\u9006\u9806\u3067\u66f8\u304f\u300d\u30b9\u30bf\u30a4\u30eb\u306b\u7531\u6765\u3057\u307e\u3059\u3002\u6700\u521d\u306f\u9055\u548c\u611f\u304c\u3042\u308b\u304b\u3082\u3057\u308c\u307e\u305b\u3093\u304c\u3001NullPointerException\u306e\u30ea\u30b9\u30af\u3092\u5287\u7684\u306b\u4e0b\u3052\u308b\u305f\u3081\u3001Java\u30d7\u30ed\u30b0\u30e9\u30de\u30fc\u306e\u9593\u3067\u306f\u5b9a\u7740\u3057\u305f\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u30b9\u30bf\u30a4\u30eb\u3067\u3059\u3002<\/div>\n<\/div>\n\n\n<div style=\"margin:48px 0 8px;display:flex;gap:12px;justify-content:center;flex-wrap:wrap;\"><a href=\"https:\/\/aikanri.genai-ai.co.jp\/seminar2-blog\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_content=cc-java-string-compare&#038;blog_slug=cc-java-string-compare\" target=\"_blank\" rel=\"noopener\" aria-label=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff08\u7121\u6599\u30fb1on1\u30fb60\u5206\uff09\u306e\u4e88\u7d04\u753b\u9762\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_seminar_claude_code_2026.jpg\" alt=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff5c\u7d4c\u55b6\u8005\u30fb\u4f1a\u793e\u5f79\u54e1\u5c02\u7528 1on1 60\u5206 \u7121\u6599\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><a href=\"https:\/\/aikanri.genai-ai.co.jp\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_campaign=cc-java-string-compare&#038;utm_content=h2-banner-kanri\" target=\"_blank\" rel=\"noopener\" aria-label=\"AI\u9b3c\u7ba1\u7406 \u516c\u5f0f\u30b5\u30a4\u30c8\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_blog_1to1.jpg\" alt=\"Claude Code\u3092\u7d4c\u55b6\u306b\u6d3b\u304b\u3057\u305f\u3044\u65b9\u3078 \u2014 AI\u9b3c\u7ba1\u7406\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><\/div>\n\n\n<div id=\"sec-03\"><\/div>\n<h2 class=\"section-header-img\" style=\"margin:32px 0 24px;border-radius:8px;overflow:hidden;background:linear-gradient(135deg,#1a1a1a 0%,#2a1015 100%);padding:32px 28px;color:#fff;position:relative;border:none;border-left:none;text-align:left;\">\n  <span class=\"section-number\" style=\"display:block;\">03<\/span>\n  <span class=\"section-label\" style=\"display:block;\">NULL SAFETY<\/span>\n  <span class=\"section-title\" style=\"display:block;\">null\u3068\u306e\u6bd4\u8f03\uff1aNullPointerException\u3092\u9632\u3050\u65b9\u6cd5<\/span>\n  <span class=\"section-desc\">Objects.equals()\u3068null\u30c1\u30a7\u30c3\u30af\u306e\u30d1\u30bf\u30fc\u30f3<\/span>\n<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Java\u306eString\u6bd4\u8f03\u3067\u6700\u3082\u5384\u4ecb\u306a\u554f\u984c\u304c<code>null<\/code>\u306e\u6271\u3044\u3067\u3059\u3002\u7279\u306b\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u30fb\u5916\u90e8API\u30fb\u30e6\u30fc\u30b6\u30fc\u5165\u529b\u304b\u3089\u53d6\u5f97\u3057\u305f\u6587\u5b57\u5217\u306b\u306f<code>null<\/code>\u304c\u6df7\u5165\u3059\u308b\u30ea\u30b9\u30af\u304c\u3042\u308a\u307e\u3059\u3002\u9069\u5207\u306anull\u51e6\u7406\u306a\u3057\u3067\u306f\u5fc5\u305aNullPointerException\u304c\u767a\u751f\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Objects.equals()\uff1a\u6700\u3082\u30b7\u30f3\u30d7\u30eb\u306anull\u5b89\u5168\u6bd4\u8f03<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Java 7\u4ee5\u964d\u3067\u5c0e\u5165\u3055\u308c\u305f<code>Objects.equals(a, b)<\/code>\u306f\u3001a\u3068b\u304c\u4e21\u65b9null\u306a\u3089<code>true<\/code>\u3001\u4e00\u65b9\u3060\u3051null\u306a\u3089<code>false<\/code>\u3001\u4e21\u65b9\u975enull\u306a\u3089<code>a.equals(b)<\/code>\u306e\u7d50\u679c\u3092\u8fd4\u3059\u3001\u3068\u3044\u3046\u6319\u52d5\u3092\u3057\u307e\u3059\u3002null\u30c1\u30a7\u30c3\u30af\u3092\u660e\u793a\u7684\u306b\u66f8\u304b\u306a\u304f\u3066\u3088\u3044\u6700\u3082\u30b7\u30f3\u30d7\u30eb\u306anull\u5b89\u5168\u6bd4\u8f03\u3067\u3059\u3002<\/p>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">import java.util.Objects;\n\nString a = null;\nString b = null;\nString c = \"hello\";\n\nSystem.out.println(Objects.equals(a, b)); \/\/ true\uff08\u4e21\u65b9null\uff09\nSystem.out.println(Objects.equals(a, c)); \/\/ false\uff08\u4e00\u65b9\u3060\u3051null\uff09\nSystem.out.println(Objects.equals(c, \"hello\")); \/\/ true\uff08\u5185\u5bb9\u304c\u540c\u3058\uff09\n\n\/\/ NullPointerException\u304c\u767a\u751f\u3057\u306a\u3044\u5b89\u5168\u306a\u6bd4\u8f03\nString userInput = getUserInput(); \/\/ null\u304c\u6765\u308b\u53ef\u80fd\u6027\u304c\u3042\u308b\nif (Objects.equals(userInput, \"admin\")) {\n    System.out.println(\"\u7ba1\u7406\u8005\u30e6\u30fc\u30b6\u30fc\");\n}<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u660e\u793a\u7684\u306anull\u30c1\u30a7\u30c3\u30af\u30d1\u30bf\u30fc\u30f3<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><code>Objects.equals()<\/code>\u304c\u4f7f\u3048\u306a\u3044\u53e4\u3044Java\u30d0\u30fc\u30b8\u30e7\u30f3\uff08Java 6\u4ee5\u524d\uff09\u3084\u3001null\u306e\u5834\u5408\u306e\u51e6\u7406\u3092\u660e\u793a\u7684\u306b\u66f8\u304d\u305f\u3044\u5834\u5408\u306f\u3001null\u30c1\u30a7\u30c3\u30af\u3092\u624b\u52d5\u3067\u884c\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">String value = getValueFromDatabase(); \/\/ null\u306e\u53ef\u80fd\u6027\u3042\u308a\n\n\/\/ \u30d1\u30bf\u30fc\u30f31\uff1anull\u3092\u6700\u521d\u306b\u30c1\u30a7\u30c3\u30af\u3057\u3066\u304b\u3089\u6bd4\u8f03\nif (value != null &amp;&amp; value.equals(\"target\")) {\n    System.out.println(\"\u4e00\u81f4\");\n}\n\n\/\/ \u30d1\u30bf\u30fc\u30f32\uff1a\u4e09\u9805\u6f14\u7b97\u5b50\u3067null\u3092\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u306b\u5909\u63db\nString safe = (value != null) ? value : \"\";\nif (safe.equals(\"target\")) {\n    System.out.println(\"\u4e00\u81f4\");\n}\n\n\/\/ \u30d1\u30bf\u30fc\u30f33\uff1aJava 8\u4ee5\u964d - Optional\u4f7f\u7528\nimport java.util.Optional;\nOptional.ofNullable(value)\n    .filter(\"target\"::equals)\n    .ifPresent(v -&gt; System.out.println(\"\u4e00\u81f4\"));<\/code><\/pre>\n\n\n\n<div style=\"background:#f8f9fa;border-left:4px solid #6b7280;border-radius:0 8px 8px 0;padding:16px 20px;margin:20px 0;\">\n  <p style=\"margin:0 0 4px;font-size:13px;font-weight:700;color:#6b7280;letter-spacing:1px;\">&#128218; \u7528\u8a9e\u89e3\u8aac<\/p>\n  <p style=\"margin:0;font-size:15px;line-height:1.7;\"><strong>String\u5b9a\u6570\u30d7\u30fc\u30eb\uff08String Pool\uff09<\/strong>\uff1aJava\u304c\u6587\u5b57\u5217\u30ea\u30c6\u30e9\u30eb\u3092\u6700\u9069\u5316\u3057\u3066\u518d\u5229\u7528\u3059\u308b\u305f\u3081\u306e\u4ed5\u7d44\u307f\u3002\u30c0\u30d6\u30eb\u30af\u30a9\u30fc\u30c8\u3067\u66f8\u304b\u308c\u305f\u6587\u5b57\u5217\u30ea\u30c6\u30e9\u30eb\uff08\u4f8b\uff1a\"hello\"\uff09\u306f\u3001JVM\u5185\u306e\u7279\u5225\u306a\u9818\u57df\uff08\u5b9a\u6570\u30d7\u30fc\u30eb\uff09\u306b\u683c\u7d0d\u3055\u308c\u308b\u3002\u540c\u3058\u30ea\u30c6\u30e9\u30eb\u304c\u8907\u6570\u306e\u5909\u6570\u306b\u4ee3\u5165\u3055\u308c\u305f\u5834\u5408\u3001\u540c\u3058\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304c\u518d\u5229\u7528\u3055\u308c\u308b\u305f\u3081\u30e1\u30e2\u30ea\u3092\u7bc0\u7d04\u3067\u304d\u308b\u3002\u305f\u3060\u3057\u3053\u306e\u305f\u3081\u3001\u5b9a\u6570\u30ea\u30c6\u30e9\u30eb\u540c\u58eb\u306e==\u6bd4\u8f03\u304ctrue\u3092\u8fd4\u3059\u30b1\u30fc\u30b9\u304c\u751f\u3058\u3001==\u304c\u6b63\u3057\u304f\u52d5\u3044\u3066\u3044\u308b\u3088\u3046\u306b\u898b\u3048\u308b\u8aa4\u89e3\u3092\u62db\u304f\u3002new String(\"hello\")\u306f\u30d7\u30fc\u30eb\u3092\u4f7f\u308f\u305a\u5225\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u751f\u6210\u3059\u308b\u3002<\/p>\n<\/div>\n\n\n\n<div style=\"background:#f0fdf4;border:1px solid #22c55e;border-radius:8px;padding:20px 24px;margin:24px 0;\">\n  <div style=\"display:flex;align-items:center;gap:8px;margin-bottom:12px;\">\n    <span style=\"font-size:18px;\">&#128161;<\/span>\n    <strong style=\"color:#16a34a;font-size:15px;\">null\u5b89\u5168\u30b3\u30fc\u30c9\u306e\u57fa\u672c\u539f\u5247<\/strong>\n  <\/div>\n  <p style=\"margin:0;font-size:15px;line-height:1.8;color:#333;\">null\u5b89\u5168\u306aString\u6bd4\u8f03\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3092\u307e\u3068\u3081\u308b\u3068\uff1a\u2460Objects.equals()\u3092\u4f7f\u3046\uff08Java 7\u4ee5\u964d\u63a8\u5968\uff09\u2461equals()\u3092\u4f7f\u3046\u5834\u5408\u306f\u5b9a\u6570\u3092\u5de6\u8fba\u306b\u7f6e\u304f\u2462null\u304c\u5165\u3063\u3066\u306f\u3044\u3051\u306a\u3044\u5f15\u6570\u306b\u306f@NonNull\u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3\u3092\u4ed8\u3051\u308b\u2463\u5916\u90e8\u304b\u3089\u306e\u5165\u529b\u306f\u5fc5\u305anull\u30c1\u30a7\u30c3\u30af\u5f8c\u306b\u51e6\u7406\u3059\u308b\u3001\u306e4\u70b9\u3067\u3059\u3002\u3053\u306e\u539f\u5247\u3092\u5b88\u308c\u3070\u3001NullPointerException\u306e\u5927\u534a\u306f\u9632\u3052\u307e\u3059\u3002<\/p>\n<\/div>\n\n\n\n<div class=\"balloon-wrap\">\n  <div class=\"balloon-icon\">\n    <img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/04\/ceo-sugasawa.jpg\" alt=\"\u4ee3\u8868\u83c5\u6fa4\">\n    <span class=\"balloon-name\">\u4ee3\u8868\u83c5\u6fa4<\/span>\n  <\/div>\n  <div class=\"balloon-body\">Objects.equals()\u3092\u4f7f\u3046\u3060\u3051\u3067null\u95a2\u9023\u306eNullPointerException\u3092\u5927\u5e45\u306b\u6e1b\u3089\u305b\u307e\u3059\u3002\u5f0a\u793e\u3067Java\u306e\u30ec\u30ac\u30b7\u30fc\u30b3\u30fc\u30c9\u3092\u30ec\u30d3\u30e5\u30fc\u3059\u308b\u3068\u3001\u300cvalue.equals(\"...\"\uff09\u300d\u3068\u3044\u3046\u5f62\u304c\u983b\u51fa\u3057\u307e\u3059\u3002\u3053\u308c\u3092\u5168\u3066\u300cObjects.equals(value, \"...\")\u300d\u306b\u7f6e\u304d\u63db\u3048\u308b\u3060\u3051\u3067\u3001\u30b5\u30fc\u30d3\u30b9\u306e\u5b89\u5b9a\u6027\u304c\u5411\u4e0a\u3059\u308b\u3053\u3068\u304c\u3042\u308a\u307e\u3059\u3002<\/div>\n<\/div>\n\n\n<div style=\"margin:48px 0 8px;display:flex;gap:12px;justify-content:center;flex-wrap:wrap;\"><a href=\"https:\/\/aikanri.genai-ai.co.jp\/seminar2-blog\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_content=cc-java-string-compare&#038;blog_slug=cc-java-string-compare\" target=\"_blank\" rel=\"noopener\" aria-label=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff08\u7121\u6599\u30fb1on1\u30fb60\u5206\uff09\u306e\u4e88\u7d04\u753b\u9762\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_seminar_claude_code_2026.jpg\" alt=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff5c\u7d4c\u55b6\u8005\u30fb\u4f1a\u793e\u5f79\u54e1\u5c02\u7528 1on1 60\u5206 \u7121\u6599\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><a href=\"https:\/\/aikanri.genai-ai.co.jp\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_campaign=cc-java-string-compare&#038;utm_content=h2-banner-kanri\" target=\"_blank\" rel=\"noopener\" aria-label=\"AI\u9b3c\u7ba1\u7406 \u516c\u5f0f\u30b5\u30a4\u30c8\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_blog_1to1.jpg\" alt=\"Claude Code\u3092\u7d4c\u55b6\u306b\u6d3b\u304b\u3057\u305f\u3044\u65b9\u3078 \u2014 AI\u9b3c\u7ba1\u7406\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><\/div>\n\n\n<div id=\"sec-04\"><\/div>\n<h2 class=\"section-header-img\" style=\"margin:32px 0 24px;border-radius:8px;overflow:hidden;background:linear-gradient(135deg,#1a1a1a 0%,#2a1015 100%);padding:32px 28px;color:#fff;position:relative;border:none;border-left:none;text-align:left;\">\n  <span class=\"section-number\" style=\"display:block;\">04<\/span>\n  <span class=\"section-label\" style=\"display:block;\">METHODS<\/span>\n  <span class=\"section-title\" style=\"display:block;\">\u305d\u306e\u4ed6\u306eString\u6bd4\u8f03\u30e1\u30bd\u30c3\u30c9\u5b8c\u5168\u89e3\u8aac<\/span>\n  <span class=\"section-desc\">compareTo\u30fbcontains\u30fbstartsWith\u30fbendsWith\u7b49\u306e\u4f7f\u3044\u5206\u3051<\/span>\n<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">equals()\u4ee5\u5916\u306b\u3082\u3001Java\u306b\u306f\u69d8\u3005\u306aString\u6bd4\u8f03\u30fb\u691c\u7d22\u30e1\u30bd\u30c3\u30c9\u304c\u3042\u308a\u307e\u3059\u3002\u7528\u9014\u306b\u5fdc\u3058\u3066\u4f7f\u3044\u5206\u3051\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u610f\u56f3\u304c\u660e\u78ba\u3067\u8aad\u307f\u3084\u3059\u3044\u30b3\u30fc\u30c9\u304c\u66f8\u3051\u307e\u3059\u3002<\/p>\n\n\n\n<table>\n<thead><tr><th>\u30e1\u30bd\u30c3\u30c9<\/th><th>\u623b\u308a\u5024<\/th><th>\u7528\u9014<\/th><th>null\u5b89\u5168<\/th><\/tr><\/thead>\n<tbody>\n<tr><td>equals(s)<\/td><td>boolean<\/td><td>\u5b8c\u5168\u4e00\u81f4\uff08\u5927\u6587\u5b57\u5c0f\u6587\u5b57\u533a\u5225\uff09<\/td><td>\u00d7\uff08NPE\uff09<\/td><\/tr>\n<tr><td>equalsIgnoreCase(s)<\/td><td>boolean<\/td><td>\u5927\u6587\u5b57\u5c0f\u6587\u5b57\u3092\u7121\u8996\u3057\u3066\u4e00\u81f4\u78ba\u8a8d<\/td><td>\u00d7\uff08NPE\uff09<\/td><\/tr>\n<tr><td>Objects.equals(a,b)<\/td><td>boolean<\/td><td>null\u5b89\u5168\u306a\u5b8c\u5168\u4e00\u81f4\u78ba\u8a8d<\/td><td>\u25ce<\/td><\/tr>\n<tr><td>compareTo(s)<\/td><td>int<\/td><td>\u8f9e\u66f8\u9806\u6bd4\u8f03\u30fb0=\u4e00\u81f4\u30fb\u8ca0=\u524d\u30fb\u6b63=\u5f8c<\/td><td>\u00d7\uff08NPE\uff09<\/td><\/tr>\n<tr><td>compareToIgnoreCase(s)<\/td><td>int<\/td><td>\u5927\u6587\u5b57\u5c0f\u6587\u5b57\u7121\u8996\u306e\u8f9e\u66f8\u9806\u6bd4\u8f03<\/td><td>\u00d7\uff08NPE\uff09<\/td><\/tr>\n<tr><td>contains(seq)<\/td><td>boolean<\/td><td>\u90e8\u5206\u6587\u5b57\u5217\u304c\u542b\u307e\u308c\u308b\u304b\u78ba\u8a8d<\/td><td>\u00d7\uff08NPE\uff09<\/td><\/tr>\n<tr><td>startsWith(prefix)<\/td><td>boolean<\/td><td>\u6307\u5b9a\u306e\u6587\u5b57\u5217\u3067\u59cb\u307e\u308b\u304b\u78ba\u8a8d<\/td><td>\u00d7\uff08NPE\uff09<\/td><\/tr>\n<tr><td>endsWith(suffix)<\/td><td>boolean<\/td><td>\u6307\u5b9a\u306e\u6587\u5b57\u5217\u3067\u7d42\u308f\u308b\u304b\u78ba\u8a8d<\/td><td>\u00d7\uff08NPE\uff09<\/td><\/tr>\n<tr><td>matches(regex)<\/td><td>boolean<\/td><td>\u6b63\u898f\u8868\u73fe\u3067\u30d1\u30bf\u30fc\u30f3\u30de\u30c3\u30c1\u30f3\u30b0<\/td><td>\u00d7\uff08NPE\uff09<\/td><\/tr>\n<tr><td>isEmpty()<\/td><td>boolean<\/td><td>\u7a7a\u6587\u5b57\u5217\u304b\u3069\u3046\u304b\u78ba\u8a8d<\/td><td>\u00d7\uff08NPE\uff09<\/td><\/tr>\n<tr><td>isBlank()<\/td><td>boolean<\/td><td>\u7a7a\u6587\u5b57\u5217\u307e\u305f\u306f\u7a7a\u767d\u306e\u307f\u304b\u78ba\u8a8d\uff08Java11+\uff09<\/td><td>\u00d7\uff08NPE\uff09<\/td><\/tr>\n<\/tbody>\n<\/table>\n\n\n\n<h3 class=\"wp-block-heading\">compareTo()\uff1a\u8f9e\u66f8\u9806\u6bd4\u8f03\u3068\u4f7f\u3044\u3069\u3053\u308d<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\"><code>compareTo()<\/code>\u306f2\u3064\u306e\u6587\u5b57\u5217\u3092\u8f9e\u66f8\u9806\u3067\u6bd4\u8f03\u3057\u3001\u6574\u6570\u5024\uff08\u8ca0\u30fb0\u30fb\u6b63\uff09\u3092\u8fd4\u3057\u307e\u3059\u3002equals()\u3068\u306f\u7570\u306a\u308aboolean\u3067\u306f\u306a\u304f\u6574\u6570\u3092\u8fd4\u3059\u305f\u3081\u3001\u300c\u7b49\u3057\u3044\u304b\u3069\u3046\u304b\u300d\u3067\u306f\u306a\u304f\u300c\u3069\u3061\u3089\u304c\u8f9e\u66f8\u7684\u306b\u524d\u304b\u300d\u3092\u8abf\u3079\u305f\u3044\u3068\u304d\u306b\u4f7f\u3044\u307e\u3059\u3002\u4e3b\u306a\u7528\u9014\u306f\u30ea\u30b9\u30c8\u306e\u30bd\u30fc\u30c8\u3067\u3059\u3002<\/p>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">String a = \"apple\";\nString b = \"banana\";\nString c = \"apple\";\n\nSystem.out.println(a.compareTo(b)); \/\/ \u8ca0\u306e\u5024\uff08apple\u306fbanana\u3088\u308a\u8f9e\u66f8\u9806\u3067\u524d\uff09\nSystem.out.println(b.compareTo(a)); \/\/ \u6b63\u306e\u5024\uff08banana\u306fapple\u3088\u308a\u8f9e\u66f8\u9806\u3067\u5f8c\uff09\nSystem.out.println(a.compareTo(c)); \/\/ 0\uff08\u5b8c\u5168\u4e00\u81f4\uff09\n\n\/\/ \u30bd\u30fc\u30c8\u3067\u306e\u6d3b\u7528\nList&lt;String&gt; list = Arrays.asList(\"banana\", \"apple\", \"cherry\");\nCollections.sort(list); \/\/ \u30c7\u30d5\u30a9\u30eb\u30c8\u3067compareTo()\u3092\u4f7f\u7528\nSystem.out.println(list); \/\/ [apple, banana, cherry]<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">contains\u30fbstartsWith\u30fbendsWith\uff1a\u90e8\u5206\u4e00\u81f4\u78ba\u8a8d<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u7279\u5b9a\u306e\u6587\u5b57\u5217\u304c\u542b\u307e\u308c\u308b\u304b\u30fb\u5148\u982d\u30fb\u672b\u5c3e\u3092\u78ba\u8a8d\u3059\u308b\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u3002\u30d5\u30a1\u30a4\u30eb\u62e1\u5f35\u5b50\u306e\u30c1\u30a7\u30c3\u30af\u30fbURL\u306e\u30d1\u30b9\u30c1\u30a7\u30c3\u30af\u30fb\u30e6\u30fc\u30b6\u30fc\u5165\u529b\u306e\u30d5\u30a3\u30eb\u30bf\u30ea\u30f3\u30b0\u306a\u3069\u3001\u5b9f\u52d9\u3067\u3088\u304f\u4f7f\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">String filename = \"report_2026-07.pdf\";\n\n\/\/ \u62e1\u5f35\u5b50\u30c1\u30a7\u30c3\u30af\nSystem.out.println(filename.endsWith(\".pdf\")); \/\/ true\nSystem.out.println(filename.endsWith(\".xlsx\")); \/\/ false\n\n\/\/ \u30d7\u30ec\u30d5\u30a3\u30c3\u30af\u30b9\u30c1\u30a7\u30c3\u30af\nSystem.out.println(filename.startsWith(\"report\")); \/\/ true\n\n\/\/ \u90e8\u5206\u6587\u5b57\u5217\u306e\u691c\u7d22\nSystem.out.println(filename.contains(\"2026\")); \/\/ true\nSystem.out.println(filename.contains(\"summary\")); \/\/ false\n\n\/\/ URL\u306e\u30d1\u30b9\u30c1\u30a7\u30c3\u30af\nString url = \"https:\/\/genai-ai.co.jp\/ai-kanri\/blog\/\";\nif (url.contains(\"\/blog\/\")) {\n    System.out.println(\"\u30d6\u30ed\u30b0\u306eURL\");\n}<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">isEmpty()\u3068isBlank()\uff1a\u7a7a\u6587\u5b57\u5217\u30fb\u7a7a\u767d\u306e\u307f\u3092\u78ba\u8a8d<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u30d5\u30a9\u30fc\u30e0\u5165\u529b\u306e\u30d0\u30ea\u30c7\u30fc\u30b7\u30e7\u30f3\u306a\u3069\u3001\u300c\u5165\u529b\u304c\u7a7a\u304b\u3069\u3046\u304b\u300d\u3092\u78ba\u8a8d\u3059\u308b\u5834\u9762\u3067\u4f7f\u3044\u307e\u3059\u3002<code>isEmpty()<\/code>\u306f\u5b8c\u5168\u306b\u7a7a\uff08\u9577\u30550\uff09\u306e\u5834\u5408\u306e\u307ftrue\u3067\u3001\u30b9\u30da\u30fc\u30b9\u306e\u307f\u306f\u7a7a\u3068\u5224\u5b9a\u3057\u307e\u305b\u3093\u3002Java 11\u4ee5\u964d\u306e<code>isBlank()<\/code>\u306f\u30b9\u30da\u30fc\u30b9\u30fb\u30bf\u30d6\u30fb\u6539\u884c\u306e\u307f\u306e\u5834\u5408\u3082true\u3092\u8fd4\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">String empty = \"\";\nString spaces = \"   \";\nString text = \"hello\";\n\nSystem.out.println(empty.isEmpty());   \/\/ true\nSystem.out.println(spaces.isEmpty());  \/\/ false\uff08\u30b9\u30da\u30fc\u30b9\u304c\u3042\u308b\uff09\nSystem.out.println(spaces.isBlank());  \/\/ true\uff08Java 11\u4ee5\u964d\uff09\n\n\/\/ \u30d0\u30ea\u30c7\u30fc\u30b7\u30e7\u30f3\u6d3b\u7528\nString username = getUserInput();\nif (username == null || username.isBlank()) {\n    throw new IllegalArgumentException(\"\u30e6\u30fc\u30b6\u30fc\u540d\u306f\u5fc5\u9808\u3067\u3059\");\n}<\/code><\/pre>\n\n\n\n<div style=\"background:#f8f9fa;border-left:4px solid #6b7280;border-radius:0 8px 8px 0;padding:16px 20px;margin:20px 0;\">\n  <p style=\"margin:0 0 4px;font-size:13px;font-weight:700;color:#6b7280;letter-spacing:1px;\">&#128218; \u7528\u8a9e\u89e3\u8aac<\/p>\n  <p style=\"margin:0;font-size:15px;line-height:1.7;\"><strong>\u6b63\u898f\u8868\u73fe\uff08Regular Expression \/ Regex\uff09<\/strong>\uff1a\u6587\u5b57\u5217\u306e\u30d1\u30bf\u30fc\u30f3\u3092\u8868\u73fe\u3059\u308b\u7279\u6b8a\u306a\u69cb\u6587\u3002\u300c@\u3088\u308a\u524d\u304c1\u6587\u5b57\u4ee5\u4e0a\u306e\u82f1\u6570\u5b57\u30fb\u30c9\u30c3\u30c8\u30fb\u30a2\u30f3\u30c0\u30fc\u30b9\u30b3\u30a2\u3067\u69cb\u6210\u3055\u308c\u308b\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u300d\u306e\u3088\u3046\u306a\u8907\u96d1\u306a\u30d1\u30bf\u30fc\u30f3\u30921\u884c\u3067\u8a18\u8ff0\u3067\u304d\u308b\u3002Java\u3067\u306fString.matches()\u3001Pattern\u30af\u30e9\u30b9\u3001Matcher\u30af\u30e9\u30b9\u3067\u6b63\u898f\u8868\u73fe\u3092\u4f7f\u7528\u3067\u304d\u308b\u3002\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u691c\u8a3c\u30fb\u96fb\u8a71\u756a\u53f7\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u78ba\u8a8d\u30fb\u30d1\u30b9\u30ef\u30fc\u30c9\u5f37\u5ea6\u30c1\u30a7\u30c3\u30af\u306a\u3069\u306e\u30d0\u30ea\u30c7\u30fc\u30b7\u30e7\u30f3\u306b\u591a\u7528\u3055\u308c\u308b\u3002<\/p>\n<\/div>\n\n\n\n<div class=\"balloon-wrap is-right\">\n  <div class=\"balloon-icon\">\n    <img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/04\/yamazaki-avatar.png\" alt=\"AI\u9b3c\u7ba1\u7406\u5c71\u5d0e\">\n    <span class=\"balloon-name\">AI\u9b3c\u7ba1\u7406\u5c71\u5d0e<\/span>\n  <\/div>\n  <div class=\"balloon-body\">contains\u3068startsWith\/endsWith\u306f\u5b9f\u52d9\u3067\u975e\u5e38\u306b\u3088\u304f\u4f7f\u3044\u307e\u3059\u3002\u4f8b\u3048\u3070\u30e6\u30fc\u30b6\u30fc\u304c\u5165\u529b\u3057\u305fURL\u304c\u81ea\u793e\u30c9\u30e1\u30a4\u30f3\u3067\u59cb\u307e\u308b\u304b\u78ba\u8a8d\u3059\u308b\u51e6\u7406\uff08startsWith\uff09\u3001\u6dfb\u4ed8\u30d5\u30a1\u30a4\u30eb\u306e\u62e1\u5f35\u5b50\u30c1\u30a7\u30c3\u30af\uff08endsWith\uff09\u3001\u30ed\u30b0\u30e1\u30c3\u30bb\u30fc\u30b8\u306b\u7279\u5b9a\u306e\u30ad\u30fc\u30ef\u30fc\u30c9\u304c\u542b\u307e\u308c\u308b\u304b\uff08contains\uff09\u306a\u3069\u3067\u3059\u3002equals()\u3060\u3051\u3067\u306a\u304f\u3001\u3053\u308c\u3089\u306e\u30e1\u30bd\u30c3\u30c9\u3082\u4f7f\u3044\u3053\u306a\u305b\u308b\u3068\u3001\u3088\u308a\u8aad\u307f\u3084\u3059\u3044\u30b3\u30fc\u30c9\u304c\u66f8\u3051\u307e\u3059\u3002<\/div>\n<\/div>\n\n\n<div style=\"margin:48px 0 8px;display:flex;gap:12px;justify-content:center;flex-wrap:wrap;\"><a href=\"https:\/\/aikanri.genai-ai.co.jp\/seminar2-blog\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_content=cc-java-string-compare&#038;blog_slug=cc-java-string-compare\" target=\"_blank\" rel=\"noopener\" aria-label=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff08\u7121\u6599\u30fb1on1\u30fb60\u5206\uff09\u306e\u4e88\u7d04\u753b\u9762\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_seminar_claude_code_2026.jpg\" alt=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff5c\u7d4c\u55b6\u8005\u30fb\u4f1a\u793e\u5f79\u54e1\u5c02\u7528 1on1 60\u5206 \u7121\u6599\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><a href=\"https:\/\/aikanri.genai-ai.co.jp\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_campaign=cc-java-string-compare&#038;utm_content=h2-banner-kanri\" target=\"_blank\" rel=\"noopener\" aria-label=\"AI\u9b3c\u7ba1\u7406 \u516c\u5f0f\u30b5\u30a4\u30c8\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_blog_1to1.jpg\" alt=\"Claude Code\u3092\u7d4c\u55b6\u306b\u6d3b\u304b\u3057\u305f\u3044\u65b9\u3078 \u2014 AI\u9b3c\u7ba1\u7406\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><\/div>\n\n\n<div id=\"sec-05\"><\/div>\n<h2 class=\"section-header-img\" style=\"margin:32px 0 24px;border-radius:8px;overflow:hidden;background:linear-gradient(135deg,#1a1a1a 0%,#2a1015 100%);padding:32px 28px;color:#fff;position:relative;border:none;border-left:none;text-align:left;\">\n  <span class=\"section-number\" style=\"display:block;\">05<\/span>\n  <span class=\"section-label\" style=\"display:block;\">BUG PATTERNS<\/span>\n  <span class=\"section-title\" style=\"display:block;\">\u3088\u304f\u3042\u308b\u30d0\u30b0\u30d1\u30bf\u30fc\u30f310\u9078\u3068\u305d\u306e\u4fee\u6b63\u65b9\u6cd5<\/span>\n  <span class=\"section-desc\">\u73fe\u5834\u3067\u5b9f\u969b\u306b\u8d77\u304d\u308bString\u6bd4\u8f03\u306e\u30df\u30b9\u3068\u6b63\u3057\u3044\u30b3\u30fc\u30c9<\/span>\n<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Java\u306eString\u6bd4\u8f03\u306b\u95a2\u3059\u308b\u30d0\u30b0\u306e\u591a\u304f\u306f\u3001\u3044\u304f\u3064\u304b\u306e\u5b9a\u756a\u30d1\u30bf\u30fc\u30f3\u306b\u5206\u985e\u3067\u304d\u307e\u3059\u3002\u4ee5\u4e0b\u306e10\u30d1\u30bf\u30fc\u30f3\u3092\u628a\u63e1\u3057\u3066\u304a\u3051\u3070\u3001\u30b3\u30fc\u30c9\u30ec\u30d3\u30e5\u30fc\u3084\u30c7\u30d0\u30c3\u30b0\u3067\u8ff7\u308f\u306a\u304f\u306a\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u30d1\u30bf\u30fc\u30f31\uff1a==\u3067String\u6bd4\u8f03\u3059\u308b\u57fa\u672c\u7684\u306a\u30df\u30b9<\/h3>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">\/\/ NG\uff08\u53c2\u7167\u6bd4\u8f03\u306b\u306a\u308b\uff09\nif (userName == \"admin\") { ... }\n\n\/\/ OK\uff08\u5024\u6bd4\u8f03\uff09\nif (\"admin\".equals(userName)) { ... }<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u30d1\u30bf\u30fc\u30f32\uff1anull\u30c1\u30a7\u30c3\u30af\u306a\u3057\u306eequals()\u547c\u3073\u51fa\u3057<\/h3>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">\/\/ NG\uff08userName\u304cnull\u306a\u3089NPE\uff09\nif (userName.equals(\"admin\")) { ... }\n\n\/\/ OK\uff08Objects.equals\u3067\u5b89\u5168\u306b\uff09\nif (Objects.equals(userName, \"admin\")) { ... }<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u30d1\u30bf\u30fc\u30f33\uff1a\u5927\u6587\u5b57\u5c0f\u6587\u5b57\u3092\u533a\u5225\u3057\u305f\u304f\u306a\u3044\u306e\u306bequals()\u3092\u4f7f\u3046<\/h3>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">\/\/ NG\uff08\"yes\"\u3068\"YES\"\u304c\u4e00\u81f4\u3057\u306a\u3044\uff09\nif (answer.equals(\"yes\")) { ... }\n\n\/\/ OK\nif (answer.equalsIgnoreCase(\"yes\")) { ... }<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u30d1\u30bf\u30fc\u30f34\uff1atrim\u3057\u306a\u3044\u3067\u30e6\u30fc\u30b6\u30fc\u5165\u529b\u3092\u6bd4\u8f03<\/h3>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">\/\/ NG\uff08\u30e6\u30fc\u30b6\u30fc\u304c\u672b\u5c3e\u306b\u30b9\u30da\u30fc\u30b9\u3092\u6253\u3063\u305f\u5834\u5408\u306b\u5931\u6557\uff09\nif (input.equals(\"admin\")) { ... }\n\n\/\/ OK\uff08\u524d\u5f8c\u306e\u7a7a\u767d\u3092\u9664\u53bb\u3057\u3066\u304b\u3089\u6bd4\u8f03\uff09\nif (\"admin\".equals(input.trim())) { ... }<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u30d1\u30bf\u30fc\u30f35\uff1acompareTo\u306e\u623b\u308a\u5024\u3092\u8aa4\u89e3\u3057\u3066\u4f7f\u3046<\/h3>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">\/\/ NG\uff08compareTo\u306f0\u304c\u4e00\u81f4\u30011\u3067\u306f\u306a\u3044\uff09\nif (a.compareTo(b) == 1) { ... }  \/\/ \u300c\u5f8c\u300d\u3092\u610f\u5473\u3059\u308b\u304c\u3001\u5fc5\u305a1\u3068\u306f\u9650\u3089\u306a\u3044\n\n\/\/ OK\uff08\u7b49\u3057\u3044\u304b\u3069\u3046\u304b\u306e\u78ba\u8a8d\u306b\u306fequals\u3092\u4f7f\u3046\uff09\nif (a.equals(b)) { ... }\n\n\/\/ compareTo\u306f\u300c\u8f9e\u66f8\u9806\u3067\u524d\u304b\u5f8c\u304b\u300d\u3092\u8abf\u3079\u308b\u305f\u3081\u306b\u4f7f\u3046\nif (a.compareTo(b) &lt; 0) {\n    System.out.println(a + \"\u306f\" + b + \"\u3088\u308a\u8f9e\u66f8\u9806\u3067\u524d\");\n}<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u30d1\u30bf\u30fc\u30f36\uff1a\u7a7a\u6587\u5b57\u5217\u3068null\u306e\u6df7\u540c<\/h3>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">String s = null;\n\n\/\/ NG\uff08null\u3068is\"\"\u306f\u9055\u3046\u3001\u3053\u306e\u6761\u4ef6\u3067\u306fnull\u306ffalse\uff09\nif (s.equals(\"\")) { ... }   \/\/ NPE\u767a\u751f\n\n\/\/ OK\uff08null\u3068\u7a7a\u6587\u5b57\u3092\u4e21\u65b9\u30c1\u30a7\u30c3\u30af\uff09\nif (s == null || s.isEmpty()) { ... }\n\n\/\/ \u307e\u305f\u306f isBlank() \u3067\u7a7a\u767d\u306e\u307f\u3082\u307e\u3068\u3081\u3066\u691c\u67fb\uff08Java 11+\uff09\nif (s == null || s.isBlank()) { ... }<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u30d1\u30bf\u30fc\u30f37\uff1achar\u578b\u3068\u306e\u6df7\u540c<\/h3>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">String s = \"A\";\n\n\/\/ NG\uff08char\u306e'A'\u3068String\u306e\"A\"\u306f\u5225\u578b\uff09\nchar c = 'A';\nif (s == c) { ... }  \/\/ \u30b3\u30f3\u30d1\u30a4\u30eb\u30a8\u30e9\u30fc\u306b\u306a\u308b\u3053\u3068\u304c\u591a\u3044\n\n\/\/ OK\nif (s.equals(String.valueOf(c))) { ... }\n\/\/ \u307e\u305f\u306f\nif (s.charAt(0) == c) { ... }  \/\/ 1\u6587\u5b57\u76ee\u3060\u3051\u6bd4\u8f03\u3059\u308b\u5834\u5408<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u30d1\u30bf\u30fc\u30f38\uff1aintern()\u3092\u4f7f\u3063\u305f==\u6bd4\u8f03\u306e\u30a2\u30f3\u30c1\u30d1\u30bf\u30fc\u30f3<\/h3>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">\/\/ NG\uff08intern()\u3067\u5b9a\u6570\u30d7\u30fc\u30eb\u306b\u8ffd\u52a0\u3059\u308c\u3070==\u304c\u901a\u308b\u304c\u3001\u53ef\u8aad\u6027\u304c\u60aa\u304f\u5371\u967a\uff09\nString a = getFromDatabase().intern();\nString b = \"hello\".intern();\nif (a == b) { ... }  \/\/ intern()\u304c\u6b63\u3057\u304f\u4f7f\u308f\u308c\u308c\u3070\u52d5\u304f\u304c...\n\n\/\/ OK\uff08\u30b7\u30f3\u30d7\u30eb\u306bequals()\u3092\u4f7f\u3046\uff09\nif (Objects.equals(a, \"hello\")) { ... }<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u30d1\u30bf\u30fc\u30f39\uff1a\u6587\u5b57\u5217\u306e\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u9055\u3044\u306b\u6c17\u3065\u304b\u306a\u3044\u6bd4\u8f03<\/h3>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">\/\/ \"2026-07-10\"\u3068\"2026\/07\/10\"\u306f\u7b49\u3057\u304f\u306a\u3044\nString dateFromDB = \"2026-07-10\";\nString userInput = \"2026\/07\/10\";\n\nSystem.out.println(dateFromDB.equals(userInput)); \/\/ false\n\n\/\/ OK\uff08\u6bd4\u8f03\u524d\u306b\u6b63\u898f\u5316\uff09\nString normalized = userInput.replace(\"\/\", \"-\");\nSystem.out.println(dateFromDB.equals(normalized)); \/\/ true<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u30d1\u30bf\u30fc\u30f310\uff1aJava\u30d0\u30fc\u30b8\u30e7\u30f3\u4f9d\u5b58\u306e\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u3046\u30a8\u30e9\u30fc<\/h3>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\">\/\/ isBlank()\u306fJava 11\u4ee5\u964d\u306e\u307f\nString s = \"  \";\n\n\/\/ Java 8\u4ee5\u524d\u3067\u306f UnsupportedOperationError \u306b\u306a\u308b\u5834\u5408\u3042\u308a\nif (s.isBlank()) { ... }  \/\/ Java 11+\u306e\u307f\n\n\/\/ Java 8\u4ee5\u524d\u306e\u4ee3\u66ff\nif (s.trim().isEmpty()) { ... }  \/\/ Java 6\u4ee5\u964d\u3067\u4f7f\u7528\u53ef\u80fd<\/code><\/pre>\n\n\n\n<div class=\"balloon-wrap\">\n  <div class=\"balloon-icon\">\n    <img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/04\/ceo-sugasawa.jpg\" alt=\"\u4ee3\u8868\u83c5\u6fa4\">\n    <span class=\"balloon-name\">\u4ee3\u8868\u83c5\u6fa4<\/span>\n  <\/div>\n  <div class=\"balloon-body\">\u4e0a\u8a1810\u30d1\u30bf\u30fc\u30f3\u306e\u591a\u304f\u306f\u300c\u30b3\u30fc\u30c9\u30ec\u30d3\u30e5\u30fc\u30671\u4eba\u304c\u6307\u6458\u3067\u304d\u308c\u3070\u5168\u30c1\u30fc\u30e0\u304c\u5b66\u3079\u308b\u300d\u985e\u306e\u3082\u306e\u3067\u3059\u3002\u30c1\u30fc\u30e0\u5185\u3067Java\u6bd4\u8f03\u306e\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u898f\u7d04\uff08equals\u3092\u4f7f\u3046\u30fbObjects.equals\u63a8\u5968\u30fbtrim\u3057\u3066\u304b\u3089\u6bd4\u8f03\u7b49\uff09\u30921\u679a\u306e\u5171\u6709\u30c9\u30ad\u30e5\u30e1\u30f3\u30c8\u306b\u307e\u3068\u3081\u3066\u304a\u304f\u3060\u3051\u3067\u3001\u540c\u3058\u30d0\u30b0\u304c\u7e70\u308a\u8fd4\u3055\u308c\u306a\u304f\u306a\u308a\u307e\u3059\u3002<\/div>\n<\/div>\n\n\n<div style=\"margin:48px 0 8px;display:flex;gap:12px;justify-content:center;flex-wrap:wrap;\"><a href=\"https:\/\/aikanri.genai-ai.co.jp\/seminar2-blog\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_content=cc-java-string-compare&#038;blog_slug=cc-java-string-compare\" target=\"_blank\" rel=\"noopener\" aria-label=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff08\u7121\u6599\u30fb1on1\u30fb60\u5206\uff09\u306e\u4e88\u7d04\u753b\u9762\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_seminar_claude_code_2026.jpg\" alt=\"Claude Code \u5b8c\u5168\u89e3\u8aac\u30bb\u30df\u30ca\u30fc\uff5c\u7d4c\u55b6\u8005\u30fb\u4f1a\u793e\u5f79\u54e1\u5c02\u7528 1on1 60\u5206 \u7121\u6599\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><a href=\"https:\/\/aikanri.genai-ai.co.jp\/?utm_source=blog&#038;utm_medium=h2banner&#038;utm_campaign=cc-java-string-compare&#038;utm_content=h2-banner-kanri\" target=\"_blank\" rel=\"noopener\" aria-label=\"AI\u9b3c\u7ba1\u7406 \u516c\u5f0f\u30b5\u30a4\u30c8\u3078\" style=\"flex:1 1 280px;max-width:360px;text-decoration:none;\"><img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/05\/cta_blog_1to1.jpg\" alt=\"Claude Code\u3092\u7d4c\u55b6\u306b\u6d3b\u304b\u3057\u305f\u3044\u65b9\u3078 \u2014 AI\u9b3c\u7ba1\u7406\" style=\"width:100%;height:auto;border-radius:8px;display:block;\"><\/a><\/div>\n\n\n<div id=\"sec-06\"><\/div>\n<h2 class=\"section-header-img\" style=\"margin:32px 0 24px;border-radius:8px;overflow:hidden;background:linear-gradient(135deg,#1a1a1a 0%,#2a1015 100%);padding:32px 28px;color:#fff;position:relative;border:none;border-left:none;text-align:left;\">\n  <span class=\"section-number\" style=\"display:block;\">06<\/span>\n  <span class=\"section-label\" style=\"display:block;\">CLAUDE CODE<\/span>\n  <span class=\"section-title\" style=\"display:block;\">Claude Code\u3067Java\u306eString\u6bd4\u8f03\u30d0\u30b0\u3092\u5373\u89e3\u6c7a\u3059\u308b\u65b9\u6cd5<\/span>\n  <span class=\"section-desc\">AI\u30a8\u30fc\u30b8\u30a7\u30f3\u30c8\u306b\u3088\u308b\u30b3\u30fc\u30c9\u30ec\u30d3\u30e5\u30fc\u30fb\u81ea\u52d5\u30c7\u30d0\u30c3\u30b0<\/span>\n<\/h2>\n\n\n\n<p class=\"wp-block-paragraph\">Java\u306eString\u6bd4\u8f03\u30d0\u30b0\u306f\u3001\u30b3\u30fc\u30c9\u3092\u898b\u308b\u3060\u3051\u3067\u306f\u6c17\u3065\u304d\u306b\u304f\u3044\u5834\u5408\u304c\u3042\u308a\u307e\u3059\u3002\u7279\u306b\u5927\u898f\u6a21\u306a\u30ec\u30ac\u30b7\u30fc\u30b3\u30fc\u30c9\u3084\u3001\u4ed6\u4eba\u304c\u66f8\u3044\u305f\u30b3\u30fc\u30c9\u306e\u30d0\u30b0\u3092\u63a2\u3059\u5834\u5408\u3001Claude Code\u3092\u4f7f\u3046\u3053\u3068\u3067\u5287\u7684\u306b\u52b9\u7387\u304c\u4e0a\u304c\u308a\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Claude Code\u306b\u300c==\u3067String\u6bd4\u8f03\u3057\u3066\u3044\u308b\u30d0\u30b0\u3092\u5168\u90e8\u898b\u3064\u3051\u3066\u76f4\u3057\u3066\u300d\u3068\u983c\u3080<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">Claude Code\u306f\u30bf\u30fc\u30df\u30ca\u30eb\u304b\u3089\u8d77\u52d5\u3057\u3001\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u306eJava\u30b3\u30fc\u30c9\u3092\u81ea\u5f8b\u7684\u306b\u8aad\u307f\u8fbc\u3093\u3067\u30ec\u30d3\u30e5\u30fc\u3067\u304d\u307e\u3059\u3002\u4f8b\u3048\u3070\u6b21\u306e\u3088\u3046\u306a\u6307\u793a\u3092\u4e0e\u3048\u308b\u3068\u3001\u554f\u984c\u306e\u3042\u308b\u30b3\u30fc\u30c9\u3092\u81ea\u52d5\u3067\u691c\u51fa\u30fb\u4fee\u6b63\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\"># Claude Code\u3078\u306e\u6307\u793a\u306e\u4f8b\uff08\u81ea\u7136\u8a00\u8a9e\u3067\u66f8\u3051\u308b\uff09\n\u300c\u3053\u306eJava\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u5168\u4f53\u3092\u8aad\u3093\u3067\u3001\nString\u6bd4\u8f03\u3067==\u3092\u4f7f\u3063\u3066\u3044\u308b\u7b87\u6240\u3092\u5168\u3066\u898b\u3064\u3051\u3066\u3001\nequals()\u307e\u305f\u306fObjects.equals()\u306b\u4fee\u6b63\u3057\u3066\u3002\nnullPointerException\u304c\u8d77\u304d\u305d\u3046\u306a\u7b87\u6240\u3082\u6559\u3048\u3066\u3002\u300d<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">Claude Code\u306f\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u5185\u306e\u5168Java\u30d5\u30a1\u30a4\u30eb\u3092\u81ea\u5f8b\u7684\u306b\u8aad\u307f\u8fbc\u307f\u3001<code>==<\/code>\u3067String\u3092\u6bd4\u8f03\u3057\u3066\u3044\u308b\u884c\u3092\u5168\u3066\u691c\u51fa\u3057\u3001\u9069\u5207\u306a\u4fee\u6b63\u3092\u63d0\u6848\u30fb\u5b9f\u884c\u3057\u307e\u3059\u300250\u30d5\u30a1\u30a4\u30eb\u3042\u308b\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3067\u3082\u3001\u4eba\u9593\u304c\u624b\u52d5\u3067grep\u3057\u30661\u3064\u305a\u3064\u78ba\u8a8d\u3059\u308b\u4f5c\u696d\u3092\u6570\u5206\u3067\u5b8c\u4e86\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<div class=\"g-flow-row\" style=\"margin:24px 0;\">\n  <div class=\"g-flow-item\">\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3092<br>Claude Code\u3067\u958b\u304f<\/div>\n  <div class=\"g-flow-arrow\">&#8594;<\/div>\n  <div class=\"g-flow-item\">\u81ea\u7136\u8a00\u8a9e\u3067<br>\u554f\u984c\u3092\u4f1d\u3048\u308b<\/div>\n  <div class=\"g-flow-arrow\">&#8594;<\/div>\n  <div class=\"g-flow-item\">\u30b3\u30fc\u30c9\u3092<br>\u81ea\u52d5\u30b9\u30ad\u30e3\u30f3<\/div>\n  <div class=\"g-flow-arrow\">&#8594;<\/div>\n  <div class=\"g-flow-item\">\u554f\u984c\u7b87\u6240\u3092<br>\u4e00\u89a7\u8868\u793a<\/div>\n  <div class=\"g-flow-arrow\">&#8594;<\/div>\n  <div class=\"g-flow-item\">\u4fee\u6b63\u6848\u3092<br>\u81ea\u52d5\u9069\u7528<\/div>\n<\/div>\n\n\n\n<h3 class=\"wp-block-heading\">NullPointerException\u306e\u30b9\u30bf\u30c3\u30af\u30c8\u30ec\u30fc\u30b9\u304b\u3089\u539f\u56e0\u3092\u5373\u7279\u5b9a<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u672c\u756a\u74b0\u5883\u3067NullPointerException\u304c\u767a\u751f\u3057\u305f\u3068\u304d\u3001\u30b9\u30bf\u30c3\u30af\u30c8\u30ec\u30fc\u30b9\uff08\u30a8\u30e9\u30fc\u30ed\u30b0\uff09\u3092Claude Code\u306b\u8cbc\u308a\u4ed8\u3051\u3066\u300c\u3053\u306e\u30a8\u30e9\u30fc\u306e\u539f\u56e0\u3068\u4fee\u6b63\u65b9\u6cd5\u3092\u6559\u3048\u3066\u300d\u3068\u6307\u793a\u3059\u308b\u3060\u3051\u3067\u3001\u6570\u5341\u79d2\u3067\u30c7\u30d0\u30c3\u30b0\u304c\u5b8c\u4e86\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<div style=\"background:#f8f9fa;border-left:4px solid #6b7280;border-radius:0 8px 8px 0;padding:16px 20px;margin:20px 0;\">\n  <p style=\"margin:0 0 4px;font-size:13px;font-weight:700;color:#6b7280;letter-spacing:1px;\">&#128218; \u7528\u8a9e\u89e3\u8aac<\/p>\n  <p style=\"margin:0;font-size:15px;line-height:1.7;\"><strong>\u30b9\u30bf\u30c3\u30af\u30c8\u30ec\u30fc\u30b9\uff08Stack Trace\uff09<\/strong>\uff1aJava\u30d7\u30ed\u30b0\u30e9\u30e0\u3067\u30a8\u30e9\u30fc\uff08\u4f8b\u5916\uff09\u304c\u767a\u751f\u3057\u305f\u3068\u304d\u306b\u51fa\u529b\u3055\u308c\u308b\u3001\u30a8\u30e9\u30fc\u306e\u767a\u751f\u7b87\u6240\u30fb\u539f\u56e0\u30fb\u547c\u3073\u51fa\u3057\u7d4c\u8def\u306e\u8a73\u7d30\u306a\u30ed\u30b0\u3002\u3069\u306e\u30af\u30e9\u30b9\u306e\u3069\u306e\u30e1\u30bd\u30c3\u30c9\u306e\u4f55\u884c\u76ee\u3067\u30a8\u30e9\u30fc\u304c\u8d77\u304d\u305f\u304b\u304c\u300cat \u30af\u30e9\u30b9\u540d.\u30e1\u30bd\u30c3\u30c9\u540d(\u30d5\u30a1\u30a4\u30eb\u540d:\u884c\u756a\u53f7)\u300d\u3068\u3044\u3046\u5f62\u3067\u5217\u6319\u3055\u308c\u308b\u3002\u30c7\u30d0\u30c3\u30b0\u306e\u51fa\u767a\u70b9\u3068\u3057\u3066\u4f7f\u3044\u3001\u554f\u984c\u306e\u3042\u308b\u30b3\u30fc\u30c9\u306e\u884c\u756a\u53f7\u3092\u7279\u5b9a\u3059\u308b\u3053\u3068\u3067\u4fee\u6b63\u7b87\u6240\u306b\u305f\u3069\u308a\u7740\u304f\u3002Claude Code\u306b\u30b9\u30bf\u30c3\u30af\u30c8\u30ec\u30fc\u30b9\u3092\u8cbc\u308a\u4ed8\u3051\u308b\u3060\u3051\u3067\u539f\u56e0\u3092\u5373\u7279\u5b9a\u3067\u304d\u308b\u3002<\/p>\n<\/div>\n\n\n\n<pre style=\"background:#1e1e2e;border-radius:8px;padding:20px 24px;margin:20px 0;overflow-x:auto;\"><code style=\"color:#cdd6f4;font-family:'Courier New',monospace;font-size:14px;line-height:1.7;\"># \u30b9\u30bf\u30c3\u30af\u30c8\u30ec\u30fc\u30b9\u3092\u305d\u306e\u307e\u307e\u8cbc\u308a\u4ed8\u3051\u3066\u6307\u793a\n\u300c\u4ee5\u4e0b\u306e\u30a8\u30e9\u30fc\u304c\u767a\u751f\u3057\u3066\u3044\u307e\u3059\u3002\u539f\u56e0\u3068\u4fee\u6b63\u65b9\u6cd5\u3092\u6559\u3048\u3066\u304f\u3060\u3055\u3044\uff1a\n\njava.lang.NullPointerException\n  at com.example.UserService.validateUser(UserService.java:45)\n  at com.example.LoginController.login(LoginController.java:23)\n  ...\n\u300d<\/code><\/pre>\n\n\n\n<p class=\"wp-block-paragraph\">Claude Code\u306f\u30a8\u30e9\u30fc\u306e\u767a\u751f\u884c\uff08UserService.java:45\uff09\u3092\u81ea\u52d5\u3067\u8aad\u307f\u8fbc\u307f\u3001\u305d\u306e\u30b3\u30f3\u30c6\u30ad\u30b9\u30c8\u3092\u5206\u6790\u3057\u3066\u300c45\u884c\u76ee\u3067userName.equals(\"admin\")\u3092\u547c\u3073\u51fa\u3057\u3066\u3044\u307e\u3059\u304c\u3001userName\u304cnull\u306e\u5834\u5408\u306bNPE\u304c\u767a\u751f\u3057\u3066\u3044\u307e\u3059\u3002Objects.equals(userName, \"admin\")\u306b\u5909\u66f4\u3057\u3066\u304f\u3060\u3055\u3044\u300d\u3068\u3044\u3046\u5177\u4f53\u7684\u306a\u4fee\u6b63\u63d0\u6848\u3092\u8fd4\u3057\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u30a8\u30f3\u30b8\u30cb\u30a2\u4e0d\u5728\u3067\u3082Claude Code\u304c\u30b3\u30fc\u30c9\u30ec\u30d3\u30e5\u30fc\u3092\u4ee3\u884c<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">\u4e2d\u5c0f\u4f01\u696d\u3084\u975e\u30a8\u30f3\u30b8\u30cb\u30a2\u7d4c\u55b6\u8005\u306b\u3068\u3063\u3066\u7279\u306b\u4fa1\u5024\u304c\u3042\u308b\u306e\u306f\u3001\u300c\u30a8\u30f3\u30b8\u30cb\u30a2\u304c\u3044\u306a\u304f\u3066\u3082Claude Code\u304c\u30b3\u30fc\u30c9\u30ec\u30d3\u30e5\u30fc\u3092\u4ee3\u884c\u3067\u304d\u308b\u300d\u3068\u3044\u3046\u70b9\u3067\u3059\u3002\u5916\u6ce8\u3057\u305fJava\u30b7\u30b9\u30c6\u30e0\u306e\u30b3\u30fc\u30c9\u3092\u53d7\u3051\u53d6\u3063\u305f\u3068\u304d\u3001\u54c1\u8cea\u30c1\u30a7\u30c3\u30af\u3092Claude Code\u306b\u4efb\u305b\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n\n\n\n<div style=\"background:#fafafa;border-radius:8px;padding:16px 20px;margin:16px 0;border-left:4px solid #dc2626;\">\n<div style=\"display:flex;align-items:flex-start;gap:8px;padding:6px 0;font-size:15px;line-height:1.6;\"><span style=\"color:#dc2626;font-size:16px;flex-shrink:0;margin-top:2px;\">&#10004;&#65039;<\/span><span>\u300c\u3053\u306eJava\u30b3\u30fc\u30c9\u5168\u4f53\u306e\u30b3\u30fc\u30c9\u30ec\u30d3\u30e5\u30fc\u3092\u3057\u3066\u3001String\u6bd4\u8f03\u306e\u554f\u984c\u30fbnull\u306e\u30ea\u30b9\u30af\u30fb\u30bb\u30ad\u30e5\u30ea\u30c6\u30a3\u4e0a\u306e\u61f8\u5ff5\u3092\u5168\u3066\u5831\u544a\u3057\u3066\u300d<\/span><\/div>\n<div style=\"display:flex;align-items:flex-start;gap:8px;padding:6px 0;font-size:15px;line-height:1.6;\"><span style=\"color:#dc2626;font-size:16px;flex-shrink:0;margin-top:2px;\">&#10004;&#65039;<\/span><span>\u300c\u3053\u306e\u30b7\u30b9\u30c6\u30e0\u3067\u6700\u3082NullPointerException\u304c\u8d77\u304d\u3084\u3059\u3044\u7b87\u6240\u306f\u3069\u3053\u304b\u5206\u6790\u3057\u3066\u3001\u30ea\u30b9\u30af\u306e\u9ad8\u3044\u9806\u306b\u30ea\u30b9\u30c8\u30a2\u30c3\u30d7\u3057\u3066\u300d<\/span><\/div>\n<div style=\"display:flex;align-items:flex-start;gap:8px;padding:6px 0;font-size:15px;line-height:1.6;\"><span style=\"color:#dc2626;font-size:16px;flex-shrink:0;margin-top:2px;\">&#10004;&#65039;<\/span><span>\u300c\u3053\u306e\u30b3\u30fc\u30c9\u3092Java 8\u304b\u3089Java 17\u306b\u79fb\u884c\u3059\u308b\u969b\u306b\u4fee\u6b63\u304c\u5fc5\u8981\u306a\u7b87\u6240\u3092\u5168\u3066\u898b\u3064\u3051\u3066\u5909\u66f4\u6848\u3092\u63d0\u793a\u3057\u3066\u300d<\/span><\/div>\n<div style=\"display:flex;align-items:flex-start;gap:8px;padding:6px 0;font-size:15px;line-height:1.6;\"><span style=\"color:#dc2626;font-size:16px;flex-shrink:0;margin-top:2px;\">&#10004;&#65039;<\/span><span>\u300cString\u6bd4\u8f03\u306e\u5b9f\u88c5\u304c\u6df7\u5728\uff08==\u30fbequals\u30fbObjects.equals\uff09\u3057\u3066\u3044\u308b\u306e\u3067\u3001\u5168\u3066Objects.equals\u306b\u7d71\u4e00\u3057\u3066\u300d<\/span><\/div>\n<\/div>\n\n\n\n<div style=\"background:linear-gradient(135deg,#1a1a1a,#2a1015);border-radius:12px;padding:20px 24px;margin:24px 0;display:flex;align-items:center;gap:16px;color:#fff;\">\n  <span style=\"font-size:36px;\">&#127942;<\/span>\n  <div>\n    <div style=\"font-size:13px;color:#dc2626;font-weight:700;letter-spacing:1px;\">VERDICT<\/div>\n    <div style=\"font-size:18px;font-weight:800;\">Claude Code\u6d3b\u7528\u3092\u63a8\u5968<\/div>\n    <div style=\"font-size:14px;color:rgba(255,255,255,0.7);margin-top:4px;\">\u30ec\u30ac\u30b7\u30fcJava\u30b3\u30fc\u30c9\u306e\u54c1\u8cea\u6539\u5584\u30fbString\u6bd4\u8f03\u30d0\u30b0\u306e\u81ea\u52d5\u4fee\u6b63\u30fbNullPointerException\u306e\u6839\u672c\u539f\u56e0\u7279\u5b9a\u306b\u306fClaude Code\u304c\u5727\u5012\u7684\u306b\u52b9\u7387\u7684\u3002\u624b\u52d5\u30ec\u30d3\u30e5\u30fc\u306e10\u5206\u306e1\u306e\u6642\u9593\u3067\u30b9\u30ad\u30e3\u30f3\u5b8c\u4e86\u3002<\/div>\n  <\/div>\n<\/div>\n\n\n\n<div class=\"balloon-wrap is-right\">\n  <div class=\"balloon-icon\">\n    <img decoding=\"async\" src=\"https:\/\/genai-ai.co.jp\/ai-kanri\/wp-content\/uploads\/2026\/04\/yamazaki-avatar.png\" alt=\"AI\u9b3c\u7ba1\u7406\u5c71\u5d0e\">\n    <span class=\"balloon-name\">AI\u9b3c\u7ba1\u7406\u5c71\u5d0e<\/span>\n  <\/div>\n  <div class=\"balloon-body\">Claude Code\u3092\u4f7f\u3063\u305f\u30b3\u30fc\u30c9\u30ec\u30d3\u30e5\u30fc\u306e\u6700\u5927\u306e\u30e1\u30ea\u30c3\u30c8\u306f\u300c\u75b2\u308c\u306a\u3044\u30fb\u898b\u843d\u3068\u3055\u306a\u3044\u30fb\u7d71\u4e00\u7684\u306a\u57fa\u6e96\u3067\u8a55\u4fa1\u3067\u304d\u308b\u300d\u3053\u3068\u3067\u3059\u3002\u4eba\u9593\u306e\u30b3\u30fc\u30c9\u30ec\u30d3\u30e5\u30fc\u306f\u96c6\u4e2d\u529b\u306e\u9650\u754c\u304c\u3042\u308a\u3001\u7279\u306b\u5927\u91cf\u306e\u30b3\u30fc\u30c9\u3067\u306f\u898b\u843d\u3068\u3057\u304c\u5897\u3048\u307e\u3059\u3002Claude Code\u306f1000\u884c\u306e\u30b3\u30fc\u30c9\u3067\u3082\u6700\u521d\u306e1\u884c\u3068\u540c\u3058\u7cbe\u5ea6\u3067\u30c1\u30a7\u30c3\u30af\u3057\u307e\u3059\u3002<\/div>\n<\/div>\n\n\n\n<p class=\"wp-block-paragraph\">Java\u306eString\u6bd4\u8f03\u554f\u984c\u3092\u542b\u3080\u3001Java\u30b7\u30b9\u30c6\u30e0\u306e\u54c1\u8cea\u6539\u5584\u30fbClaude Code\u5c0e\u5165\u306b\u3064\u3044\u3066\u500b\u5225\u76f8\u8ac7\u3092\u3054\u5e0c\u671b\u306e\u65b9\u306f\u3001\u5f0a\u793eAI\u9b3c\u7ba1\u7406\u306e\u516c\u5f0fLINE\u307e\u305f\u306f\u304a\u554f\u3044\u5408\u308f\u305b\u30d5\u30a9\u30fc\u30e0\u304b\u3089\u3054\u9023\u7d61\u304f\u3060\u3055\u3044\u3002Java\u306e\u30b3\u30fc\u30c9\u30ec\u30d3\u30e5\u30fc\u4ee3\u884c\u304b\u3089Claude Code\u6d3b\u7528\u652f\u63f4\u307e\u3067\u5bfe\u5fdc\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n\n<div style=\"background:linear-gradient(135deg,#1a1a1a 0%,#2a1015 100%);border-radius:16px;padding:36px 32px;margin:48px 0 16px;color:#fff;\">\n  <p style=\"font-size:13px;font-weight:700;color:#dc2626;letter-spacing:2px;margin:0 0 12px;\">NEXT STEP<\/p>\n  <p style=\"font-size:22px;font-weight:800;line-height:1.5;margin:0 0 20px;\">\u3053\u306e\u8a18\u4e8b\u306e\u5185\u5bb9\u3092\u3001\u3042\u306a\u305f\u306e\u30d3\u30b8\u30cd\u30b9\u3067<br>\u5b9f\u8df5\u3057\u3066\u307f\u307e\u305b\u3093\u304b\uff1f<\/p>\n  <div style=\"background:rgba(255,255,255,0.06);border:1px solid rgba(255,255,255,0.12);border-radius:12px;padding:24px;max-width:560px;margin:0 auto;\">\n    <p style=\"font-size:13px;color:#dc2626;font-weight:700;margin:0 0 8px;\">AI\u6d3b\u7528\u3092\u81ea\u793e\u3067\u56de\u305b\u308b\u3088\u3046\u306b\u306a\u308a\u305f\u3044\u65b9\u3078<\/p>\n    <p style=\"font-size:20px;font-weight:800;margin:0 0 12px;\">AI\u9b3c\u7ba1\u7406<\/p>\n    <p style=\"font-size:14px;color:rgba(255,255,255,0.75);margin:0 0 20px;line-height:1.7;\">Claude Code\u30fbCowork\u5c0e\u5165\u652f\u63f4\u304b\u3089\u696d\u52d9\u8a2d\u8a08\u30fb\u793e\u5185\u6d78\u900f\u307e\u3067\u5b9f\u8df5\u30d9\u30fc\u30b9\u3067\u4f34\u8d70\u3002\u300c\u81ea\u793e\u3067\u56de\u305b\u308b\u7d44\u7e54\u300d\u309290\u65e5\u3067\u4f5c\u308b\u7d4c\u55b6\u8005\u5411\u3051\u30c8\u30ec\u30fc\u30cb\u30f3\u30b0\u3002<\/p>\n    <div style=\"text-align:center;\">\n      <a href=\"https:\/\/aikanri.genai-ai.co.jp\/?utm_source=blog&utm_medium=article&utm_campaign=cc-java-string-compare&utm_content=next-step-cta\" target=\"_blank\" rel=\"noopener\" style=\"display:inline-block;background:#dc2626;color:#fff;font-weight:700;font-size:15px;padding:14px 32px;border-radius:30px;text-decoration:none;\">AI\u9b3c\u7ba1\u7406\u3092\u8a73\u3057\u304f\u898b\u308b \u2192<\/a>\n    <\/div>\n  <\/div>\n<\/div>\n\n\n\n<h2 class=\"wp-block-heading\" id=\"faq\">\u3088\u304f\u3042\u308b\u8cea\u554f<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">Q. Java\u3067String\u3092\u6bd4\u8f03\u3059\u308b\u3068\u304d\u306f\u4f55\u3092\u4f7f\u3048\u3070\u3088\u3044\u3067\u3059\u304b\uff1f<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. \u57fa\u672c\u306fObjects.equals()\uff08Java 7\u4ee5\u964d\uff09\u306e\u4f7f\u7528\u3092\u63a8\u5968\u3057\u307e\u3059\u3002equals()\u3092\u76f4\u63a5\u4f7f\u3046\u5834\u5408\u306f\u300c\u5b9a\u6570.equals(\u5909\u6570)\u300d\u306e\u5f62\u3067\u66f8\u304f\u3068null\u5b89\u5168\u3067\u3059\u3002\u5927\u6587\u5b57\u5c0f\u6587\u5b57\u3092\u7121\u8996\u3057\u305f\u3044\u5834\u5408\u306fequalsIgnoreCase()\u3092\u4f7f\u3044\u307e\u3059\u3002==\u6f14\u7b97\u5b50\u306f\u53c2\u7167\u6bd4\u8f03\uff08\u30e1\u30e2\u30ea\u30a2\u30c9\u30ec\u30b9\u306e\u6bd4\u8f03\uff09\u306a\u306e\u3067\u3001\u6587\u5b57\u5217\u306e\u5185\u5bb9\u6bd4\u8f03\u306b\u306f\u7d76\u5bfe\u306b\u4f7f\u308f\u306a\u3044\u3067\u304f\u3060\u3055\u3044\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Q. \u300c==\u300d\u3067\u3082\u52d5\u3044\u3066\u3044\u308b\u30b1\u30fc\u30b9\u304c\u3042\u308b\u306e\u306f\u306a\u305c\u3067\u3059\u304b\uff1f<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. Java\u306e\u300cString\u5b9a\u6570\u30d7\u30fc\u30eb\u300d\u3068\u3044\u3046\u6700\u9069\u5316\u6a5f\u80fd\u306b\u3088\u308a\u3001\u540c\u3058\u6587\u5b57\u5217\u30ea\u30c6\u30e9\u30eb\u306f\u540c\u3058\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3068\u3057\u3066\u518d\u5229\u7528\u3055\u308c\u307e\u3059\u3002\u305d\u306e\u305f\u3081\u3001\u30b3\u30fc\u30c9\u5185\u3067\u300c\"hello\" == \"hello\"\u300d\u306e\u3088\u3046\u306b\u5b9a\u6570\u540c\u58eb\u3092\u6bd4\u8f03\u3059\u308b\u5834\u5408\u306ftrue\u306b\u306a\u308a\u307e\u3059\u3002\u3057\u304b\u3057\u3001\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u30fb\u30e6\u30fc\u30b6\u30fc\u5165\u529b\u30fb\u5916\u90e8API\u304b\u3089\u53d6\u5f97\u3057\u305f\u6587\u5b57\u5217\u306f\u5225\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u306a\u308b\u305f\u3081\u3001==\u306ffalse\u306b\u306a\u308a\u307e\u3059\u3002\u3053\u306e\u4e0d\u5b89\u5b9a\u306a\u6319\u52d5\u3092\u907f\u3051\u308b\u305f\u3081\u3001\u5e38\u306bequals()\u3092\u4f7f\u3063\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Q. NullPointerException\u3092\u5b8c\u5168\u306b\u9632\u3050\u65b9\u6cd5\u306f\u3042\u308a\u307e\u3059\u304b\uff1f<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. \u5b8c\u5168\u9632\u6b62\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u306f\u2460\u5916\u90e8\u304b\u3089\u306e\u5165\u529b\u306f\u5fc5\u305anull\u30c1\u30a7\u30c3\u30af\u2461String\u6bd4\u8f03\u306b\u306fObjects.equals()\u3092\u4f7f\u7528\u2462@NonNull\u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3\u3092\u4f7f\u3063\u3066null\u4e0d\u53ef\u3092\u660e\u793a\u2463Optional<String>\u578b\u3092\u6d3b\u7528\u3057\u3066null\u3092\u8fd4\u3055\u306a\u3044\u8a2d\u8a08\u2464Java 17\u4ee5\u964d\u306eRecord\u578b\u3084sealed class\u3067null\u3092\u8a2d\u8a08\u304b\u3089\u6392\u9664\u3059\u308b\u3001\u306e5\u3064\u3067\u3059\u3002\u7279\u306b\u2460\u3068\u2461\u3092\u5b88\u308b\u3060\u3051\u3067\u3001\u73fe\u5834\u3067\u767a\u751f\u3059\u308bNPE\u306e\u5927\u534a\u306f\u9632\u3052\u307e\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Q. equals\u3068compareTo\u306e\u4f7f\u3044\u5206\u3051\u3092\u6559\u3048\u3066\u304f\u3060\u3055\u3044\u3002<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. \u300c\u540c\u3058\u304b\u9055\u3046\u304b\u300d\u3092\u78ba\u8a8d\u3059\u308b\u306b\u306fequals()\u3092\u4f7f\u3044\u307e\u3059\u3002\u300c\u8f9e\u66f8\u9806\u3067A\u3068B\u3069\u3061\u3089\u304c\u524d\u304b\u300d\u3092\u8abf\u3079\u305f\u3044\u3068\u304d\u306fcompareTo()\u3092\u4f7f\u3044\u307e\u3059\u3002compareTo()\u306f\u30ea\u30b9\u30c8\u306e\u30bd\u30fc\u30c8\u30fb\u30c4\u30ea\u30fc\u69cb\u9020\u30fb\u30a2\u30eb\u30d5\u30a1\u30d9\u30c3\u30c8\u9806\u306e\u4e26\u3079\u66ff\u3048\u306a\u3069\u3067\u4f7f\u7528\u3057\u307e\u3059\u3002compareTo()\u306e\u623b\u308a\u5024\uff1a0=\u540c\u3058\u3001\u8ca0\u306e\u5024=\u547c\u3073\u51fa\u3057\u5143\u304c\u5148\u3001\u6b63\u306e\u5024=\u547c\u3073\u51fa\u3057\u5143\u304c\u5f8c \u3067\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Q. Claude Code\u306fJava\u306e\u30d0\u30b0\u4fee\u6b63\u306b\u5b9f\u969b\u306b\u4f7f\u3048\u307e\u3059\u304b\uff1f<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. \u306f\u3044\u3001\u975e\u5e38\u306b\u6709\u52b9\u3067\u3059\u3002\u7279\u306b\u300c==\u3067String\u6bd4\u8f03\u3057\u3066\u3044\u308b\u7b87\u6240\u3092\u5168\u30d5\u30a1\u30a4\u30eb\u304b\u3089\u691c\u51fa\u3057\u3066\u4fee\u6b63\u300d\u300c\u30b9\u30bf\u30c3\u30af\u30c8\u30ec\u30fc\u30b9\u304b\u3089\u539f\u56e0\u30b3\u30fc\u30c9\u3092\u7279\u5b9a\u300d\u300cnull\u304c\u6765\u308b\u53ef\u80fd\u6027\u306e\u3042\u308b\u7b87\u6240\u3092\u5168\u90e8\u6d17\u3044\u51fa\u3059\u300d\u3068\u3044\u3046\u4f5c\u696d\u306f\u3001Claude Code\u304c\u82e6\u624b\u3068\u3059\u308b\u9818\u57df\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u5168\u4f53\u306e\u30b9\u30ad\u30e3\u30f3\u306f\u6570\u5206\u3067\u5b8c\u4e86\u3057\u3001\u624b\u52d5\u30ec\u30d3\u30e5\u30fc\u306b\u6bd4\u3079\u3066\u898b\u843d\u3068\u3057\u304c\u5c11\u306a\u3044\u70b9\u304c\u5f37\u307f\u3067\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Q. Java\u4ee5\u5916\u306e\u8a00\u8a9e\u3067\u306fString\u6bd4\u8f03\u306b==\u304c\u4f7f\u3048\u307e\u3059\u304b\uff1f<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. Python\u3067\u306f==\u304c\u5024\u6bd4\u8f03\uff08Java\u306eequals\u76f8\u5f53\uff09\u3068\u3057\u3066\u52d5\u4f5c\u3059\u308b\u305f\u3081\u3001\u6587\u5b57\u5217\u6bd4\u8f03\u306b==\u3092\u4f7f\u3063\u3066\u554f\u984c\u3042\u308a\u307e\u305b\u3093\u3002PHP\u3082==\u3067\u5024\u6bd4\u8f03\u304c\u3067\u304d\u307e\u3059\u3002\u305f\u3060\u3057\u3001Java\u3084C#\u306e\u3088\u3046\u306b\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u6307\u5411\u3067\u53c2\u7167\u578b\u3092\u6301\u3064\u8a00\u8a9e\u3067\u306f\u3001==\u304c\u53c2\u7167\u6bd4\u8f03\u306b\u306a\u308b\u30b1\u30fc\u30b9\u304c\u3042\u308b\u305f\u3081\u6ce8\u610f\u304c\u5fc5\u8981\u3067\u3059\u3002C#\u3067\u3082string.Equals()\u307e\u305f\u306foperator==\uff08string\u578b\u5c02\u7528\u306b\u30aa\u30fc\u30d0\u30fc\u30ed\u30fc\u30c9\u3055\u308c\u3066\u3044\u308b\uff09\u304c\u5b89\u5168\u3067\u3059\u3002<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">Q. isBlank()\u3068isEmpty()\u306e\u9055\u3044\u306f\u4f55\u3067\u3059\u304b\uff1f<\/h3>\n\n\n\n<p class=\"wp-block-paragraph\">A. isEmpty()\u306f\u6587\u5b57\u5217\u306e\u9577\u3055\u304c0\u306e\u3068\u304d\uff08\u5b8c\u5168\u306b\u7a7a\u306e\u3068\u304d\uff09\u306e\u307ftrue\u3092\u8fd4\u3057\u307e\u3059\u3002isBlank()\uff08Java 11\u4ee5\u964d\uff09\u306f\u3055\u3089\u306b\u300c\u30b9\u30da\u30fc\u30b9\u30fb\u30bf\u30d6\u30fb\u6539\u884c\u306e\u307f\u3067\u69cb\u6210\u3055\u308c\u3066\u3044\u308b\u5834\u5408\u300d\u3082true\u3092\u8fd4\u3057\u307e\u3059\u3002\u30e6\u30fc\u30b6\u30fc\u5165\u529b\u306e\u30d0\u30ea\u30c7\u30fc\u30b7\u30e7\u30f3\u3067\u306fisBlank()\u306e\u65b9\u304c\u5b9f\u7528\u7684\u3067\u3059\uff08\u30e6\u30fc\u30b6\u30fc\u304c\u30b9\u30da\u30fc\u30b9\u3060\u3051\u5165\u529b\u3057\u305f\u30b1\u30fc\u30b9\u3092\u30ad\u30e3\u30c3\u30c1\u3067\u304d\u308b\uff09\u3002Java 8\u4ee5\u524d\u3092\u4f7f\u3063\u3066\u3044\u308b\u5834\u5408\u306f\u3001\u4ee3\u308f\u308a\u306bs.trim().isEmpty()\u3067\u540c\u69d8\u306e\u52b9\u679c\u304c\u5f97\u3089\u308c\u307e\u3059\u3002<\/p>\n\n\n\n<script type=\"application\/ld+json\">\n{\n  \"@context\": \"https:\/\/schema.org\",\n  \"@type\": \"FAQPage\",\n  \"mainEntity\": [\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Java\u3067String\u3092\u6bd4\u8f03\u3059\u308b\u3068\u304d\u306f\u4f55\u3092\u4f7f\u3048\u3070\u3088\u3044\u3067\u3059\u304b\uff1f\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"\u57fa\u672c\u306fObjects.equals()\uff08Java 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\"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"\u300c\u540c\u3058\u304b\u9055\u3046\u304b\u300d\u3092\u78ba\u8a8d\u3059\u308b\u306b\u306fequals()\u3092\u4f7f\u3044\u307e\u3059\u3002\u300c\u8f9e\u66f8\u9806\u3067A\u3068B\u3069\u3061\u3089\u304c\u524d\u304b\u300d\u3092\u8abf\u3079\u305f\u3044\u3068\u304d\u306fcompareTo()\u3092\u4f7f\u3044\u307e\u3059\u3002compareTo()\u306f\u30ea\u30b9\u30c8\u306e\u30bd\u30fc\u30c8\u30fb\u30c4\u30ea\u30fc\u69cb\u9020\u30fb\u30a2\u30eb\u30d5\u30a1\u30d9\u30c3\u30c8\u9806\u306e\u4e26\u3079\u66ff\u3048\u306a\u3069\u3067\u4f7f\u7528\u3057\u307e\u3059\u3002compareTo()\u306e\u623b\u308a\u5024\uff1a0=\u540c\u3058\u3001\u8ca0\u306e\u5024=\u547c\u3073\u51fa\u3057\u5143\u304c\u5148\u3001\u6b63\u306e\u5024=\u547c\u3073\u51fa\u3057\u5143\u304c\u5f8c \u3067\u3059\u3002\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Claude Code\u306fJava\u306e\u30d0\u30b0\u4fee\u6b63\u306b\u5b9f\u969b\u306b\u4f7f\u3048\u307e\u3059\u304b\uff1f\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": \"\u306f\u3044\u3001\u975e\u5e38\u306b\u6709\u52b9\u3067\u3059\u3002\u7279\u306b\u300c==\u3067String\u6bd4\u8f03\u3057\u3066\u3044\u308b\u7b87\u6240\u3092\u5168\u30d5\u30a1\u30a4\u30eb\u304b\u3089\u691c\u51fa\u3057\u3066\u4fee\u6b63\u300d\u300c\u30b9\u30bf\u30c3\u30af\u30c8\u30ec\u30fc\u30b9\u304b\u3089\u539f\u56e0\u30b3\u30fc\u30c9\u3092\u7279\u5b9a\u300d\u300cnull\u304c\u6765\u308b\u53ef\u80fd\u6027\u306e\u3042\u308b\u7b87\u6240\u3092\u5168\u90e8\u6d17\u3044\u51fa\u3059\u300d\u3068\u3044\u3046\u4f5c\u696d\u306f\u3001Claude Code\u304c\u82e6\u624b\u3068\u3059\u308b\u9818\u57df\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u5168\u4f53\u306e\u30b9\u30ad\u30e3\u30f3\u306f\u6570\u5206\u3067\u5b8c\u4e86\u3057\u3001\u624b\u52d5\u30ec\u30d3\u30e5\u30fc\u306b\u6bd4\u3079\u3066\u898b\u843d\u3068\u3057\u304c\u5c11\u306a\u3044\u70b9\u304c\u5f37\u307f\u3067\u3059\u3002\"\n      }\n    },\n    {\n      \"@type\": \"Question\",\n      \"name\": \"Java\u4ee5\u5916\u306e\u8a00\u8a9e\u3067\u306fString\u6bd4\u8f03\u306b==\u304c\u4f7f\u3048\u307e\u3059\u304b\uff1f\",\n      \"acceptedAnswer\": {\n        \"@type\": \"Answer\",\n        \"text\": 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8\u4ee5\u524d\u3092\u4f7f\u3063\u3066\u3044\u308b\u5834\u5408\u306f\u3001\u4ee3\u308f\u308a\u306bs.trim().isEmpty()\u3067\u540c\u69d8\u306e\u52b9\u679c\u304c\u5f97\u3089\u308c\u307e\u3059\u3002\"\n      }\n    }\n  ]\n}\n<\/script>\n\n\n","protected":false},"excerpt":{"rendered":"<p>\u3053\u306e\u8a18\u4e8b\u306e\u5185\u5bb9 01Java\u306eString\u6bd4\u8f03\u306e\u57fa\u672c\uff1a\u300c==\u300d\u3068\u300cequals()\u300d\u306e\u672c\u8cea\u7684\u306a\u9055\u3044 02equals()\u306e\u6b63\u3057\u3044\u4f7f\u3044\u65b9\u3068\u5fdc\u7528 03null\u3068\u306e\u6bd4\u8f03\uff1aNullPointerException\u3092\u9632\u3050\u65b9\u6cd5 04 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