{"id":3229,"date":"2022-02-08T19:00:30","date_gmt":"2022-02-08T10:00:30","guid":{"rendered":"https:\/\/www.bold.ne.jp\/engineer-club\/?p=3229"},"modified":"2025-11-19T10:06:10","modified_gmt":"2025-11-19T01:06:10","slug":"java-tostring","status":"publish","type":"post","link":"https:\/\/www.bold.ne.jp\/engineer-club\/java-tostring","title":{"rendered":"Java\u306etoString\u30e1\u30bd\u30c3\u30c9\u3068\u306f\uff1f\u6587\u5b57\u5217\u306b\u5909\u63db\u3057\u305f\u3044\u6642\u306etoString\u306e\u4f7f\u3044\u65b9\u3010valueOf\u3068\u306e\u9055\u3044\u3082\u89e3\u8aac\u3011"},"content":{"rendered":"<p>toString\u30e1\u30bd\u30c3\u30c9\u306f\u6587\u5b57\u5217\u306b\u5909\u63db\u3059\u308b\u969b\u306b\u4f7f\u7528\u3059\u308b\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u3002<\/p>\n<p>\u6570\u5024\u578b\u3084\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u4e2d\u8eab\u3092\u6587\u5b57\u5217\u3068\u3057\u3066\u53d6\u5f97\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<br \/>\n\u305f\u3060\u3057\u81ea\u4f5c\u30af\u30e9\u30b9\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u5834\u5408\u3001\u4e2d\u8eab\u3092\u610f\u56f3\u3057\u305f\u6587\u5b57\u5217\u3068\u3057\u3066\u53d6\u5f97\u3059\u308b\u306b\u306f\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<p>\u305d\u3093\u306a<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u304c\u3001\u5b9f\u306f<span>Java<\/span>\u3092\u5b66\u3076\u4e2d\u3067\u521d\u671f\u306e\u6bb5\u968e\u304b\u3089\u77e5\u3089\u305a\u77e5\u3089\u305a\u306e\u3046\u3061\u306b\u304a\u4e16\u8a71\u306b\u306a\u3063\u3066\u3044\u308b\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u3079\u3066\u306e<span>Java<\/span>\u30a8\u30f3\u30b8\u30cb\u30a2\u306b\u3068\u3063\u3066\u306a\u3058\u307f\u6df1\u3044\u30e1\u30bd\u30c3\u30c9\u306a\u3093\u3067\u3059\u3002<\/p>\n<div id=\"toc_container\" class=\"no_bullets\"><p class=\"toc_title\">\u76ee\u6b21<\/p><ul class=\"toc_list\"><li><a href=\"#JavatoString\">\uff11\uff0eJava\u306etoString\u30e1\u30bd\u30c3\u30c9\u3068\u306f<\/a><ul><li><a href=\"#-langObject\">\uff11-\uff11\uff0elang.Object\u30af\u30e9\u30b9\u3067\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u30e1\u30bd\u30c3\u30c9<\/a><\/li><li><a href=\"#i\">\uff11-\uff12\uff0e\u6587\u5b57\u5217\u306b\u5909\u63db\u3059\u308b\u305f\u3081\u306e\u30e1\u30bd\u30c3\u30c9<\/a><\/li><li><a href=\"#-inttoStringString\">\uff11-\uff13\uff0eint\u578b\u3092toString\u30e1\u30bd\u30c3\u30c9\u3067String\u578b\u306b\u5909\u63db\u3057\u3088\u3046<\/a><\/li><\/ul><\/li><li><a href=\"#JavatoString-2\">\uff12\uff0e\u3010Java\u3011\u81ea\u4f5c\u30af\u30e9\u30b9\u306etoString\u30e1\u30bd\u30c3\u30c9\u306f\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3057\u3088\u3046<\/a><\/li><li><a href=\"#JavatoStringvalueOf\">\uff13\uff0e\u3010Java\u3011toString\u30e1\u30bd\u30c3\u30c9\u306e\u6ce8\u610f\u70b9\u3001valueOf\u30e1\u30bd\u30c3\u30c9\u3068\u306e\u9055\u3044<\/a><\/li><\/ul><\/div>\n<h2><span id=\"JavatoString\">\uff11\uff0eJava\u306etoString\u30e1\u30bd\u30c3\u30c9\u3068\u306f<\/span><\/h2>\n<h3><span id=\"-langObject\">\uff11-\uff11\uff0elang.Object\u30af\u30e9\u30b9\u3067\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u30e1\u30bd\u30c3\u30c9<\/span><\/h3>\n<p>toString\u30e1\u30bd\u30c3\u30c9\u306f<span>Object<\/span>\u30af\u30e9\u30b9\u3067\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u3002API\u306b\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u8a18\u8f09\u3055\u308c\u3066\u3044\u307e\u3059\u3002<\/p>\n<p><a href=\"https:\/\/www.bold.ne.jp\/engineer-club\/wp-content\/uploads\/2022\/01\/toString\u30e1\u30bd\u30c3\u30c9\u3068\u306f-scaled.jpg\"><img decoding=\"async\" loading=\"lazy\" src=\"https:\/\/www.bold.ne.jp\/engineer-club\/wp-content\/uploads\/2022\/01\/toString\u30e1\u30bd\u30c3\u30c9\u3068\u306f-scaled.jpg\" alt=\"toString\u30e1\u30bd\u30c3\u30c9\u3068\u306f\" width=\"2560\" height=\"611\" class=\"alignnone size-full wp-image-3231\" srcset=\"https:\/\/www.bold.ne.jp\/engineer-club\/wp-content\/uploads\/2022\/01\/toString\u30e1\u30bd\u30c3\u30c9\u3068\u306f-scaled.jpg 2560w, https:\/\/www.bold.ne.jp\/engineer-club\/wp-content\/uploads\/2022\/01\/toString\u30e1\u30bd\u30c3\u30c9\u3068\u306f-1024x244.jpg 1024w, https:\/\/www.bold.ne.jp\/engineer-club\/wp-content\/uploads\/2022\/01\/toString\u30e1\u30bd\u30c3\u30c9\u3068\u306f-768x183.jpg 768w, https:\/\/www.bold.ne.jp\/engineer-club\/wp-content\/uploads\/2022\/01\/toString\u30e1\u30bd\u30c3\u30c9\u3068\u306f-1536x367.jpg 1536w, https:\/\/www.bold.ne.jp\/engineer-club\/wp-content\/uploads\/2022\/01\/toString\u30e1\u30bd\u30c3\u30c9\u3068\u306f-2048x489.jpg 2048w\" sizes=\"(max-width: 2560px) 100vw, 2560px\" \/><\/a><\/p>\n<p>Java\u3067\u306f\u3059\u3079\u3066\u306e\u30af\u30e9\u30b9\u304c<span>Object<\/span>\u30af\u30e9\u30b9\u3092\u7d99\u627f\u3057\u3066\u3044\u307e\u3059\u306e\u3067\u3001\u3069\u306e\u30af\u30e9\u30b9\u3067\u3082<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u3046\u3053\u3068\u304c\u53ef\u80fd\u3067\u3059\u3002<\/p>\n<h3><span id=\"i\">\uff11-\uff12\uff0e\u6587\u5b57\u5217\u306b\u5909\u63db\u3059\u308b\u305f\u3081\u306e\u30e1\u30bd\u30c3\u30c9<\/span><\/h3>\n<p>API\u306b\u3082\u66f8\u304b\u308c\u3066\u3044\u308b\u901a\u308a\u3001<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u306f\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u30c6\u30ad\u30b9\u30c8\u3067\u8868\u3059\u305f\u3081\u306e\u6587\u5b57\u5217\u3092\u8fd4\u3059\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u3002<\/p>\n<p>\u305f\u3068\u3048\u3070\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u5f15\u6570\u306b\u3057\u305f<span>System.out.print<\/span>\u30e1\u30bd\u30c3\u30c9\u3067\u306f\u5185\u90e8\u3067<span>String.valueOf<\/span>\u30e1\u30bd\u30c3\u30c9\u304c\u547c\u3073\u51fa\u3055\u308c\u3066\u3044\u307e\u3059\u3002\u3053\u306e<span>valueOf<\/span>\u30e1\u30bd\u30c3\u30c9\u3067\u5f15\u6570\u306e\u578b\u306b\u5fdc\u3058\u305f<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u304c\u547c\u3073\u51fa\u3055\u308c\u308b\u3053\u3068\u3067\u6587\u5b57\u5217\u304c\u51fa\u529b\u3055\u308c\u308b\u4ed5\u7d44\u307f\u306b\u306a\u3063\u3066\u3044\u307e\u3059\u3002<\/p>\n<p>\u5192\u982d\u3067\u77e5\u3089\u305a\u306e\u3046\u3061\u306b\u304a\u4e16\u8a71\u306b\u306a\u3063\u3066\u3044\u308b\u306a\u3058\u307f\u6df1\u3044\u30e1\u30bd\u30c3\u30c9\u3068\u3044\u3063\u305f\u306e\u306f\u307e\u3055\u306b\u3053\u306e\u70b9\u3067\u3001<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u3046\u3053\u3068\u3067\u69d8\u3005\u306a\u578b\u306e\u30af\u30e9\u30b9\u3092\u6587\u5b57\u5217\u3068\u3057\u3066\u53d6\u5f97\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u308b\u306e\u3067\u3059\u3002<\/p>\n<h3><span id=\"-inttoStringString\"><strong>\uff11-\uff13\uff0eint<\/strong><strong>\u578b\u3092<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u3067<span>String<\/span>\u578b\u306b\u5909\u63db\u3057\u3088\u3046<\/strong><\/span><\/h3>\n<p>\u3067\u306f\u3001\u3053\u3053\u304b\u3089\u306f\u5177\u4f53\u7684\u306b<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u306e\u4f7f\u3044\u65b9\u3092\u898b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002\u307e\u305a\u306f\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u578b\u306e\u4e2d\u3067\u3082\u6570\u5024\u578b\u306e\u4ee3\u8868\u3068\u3057\u3066<span>int<\/span>\u578b\u3092\u4f8b\u306b\u3057\u307e\u3059\u3002\uff08\u4ed6\u306e\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u578b\u3082\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u306f\u5171\u901a\u3067\u3059\uff09<\/p>\n<pre class=\"prettyprint lang:default decode:true\">int num1 = 123;\r\nint num2 = 456;\r\nSystem.out.println(num1 + num2);\r\n\r\nString strNum1 = Integer.toString(num1);\r\nString strNum2 = Integer.toString(num2);\r\nSystem.out.println(strNum1 + strNum2);\r\n<\/pre>\n<p>\u4e0a\u8a18\u306e\u30b3\u30fc\u30c9\u306e\u7d50\u679c\u306f\u3001<\/p>\n<p>\uff0d\uff0d\uff0d<br \/>\n579<br \/>\n123456<br \/>\n\uff0d\uff0d\uff0d<\/p>\n<p>\u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n<p>num1\u3068<span>num2<\/span>\u306f<span>int<\/span>\u578b\u306e\u5909\u6570\u306a\u306e\u3067<span>println<\/span>\u30e1\u30bd\u30c3\u30c9\u306e\u5f15\u6570\u3067<span>+<\/span>\u6f14\u7b97\u5b50\u3092\u4f7f\u7528\u3057\u305f\u5834\u5408\u306f\u5024\u540c\u58eb\u306e\u8db3\u3057\u7b97\u304c\u884c\u308f\u308c\u307e\u3059\u3002\u5bfe\u3057\u3066<span>strNum1<\/span>\u3068<span>strNum2<\/span>\u306e\u4e2d\u8eab\u306f<span>Integer<\/span>\u30af\u30e9\u30b9\u306e<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u3067<span>int<\/span>\u578b\u306e<span>num1<\/span>\u3068<span>num2<\/span>\u3092<span>String<\/span>\u578b\u306b\u5909\u63db\u3057\u305f\u3082\u306e\u3067\u3059\u3002\u3053\u306e\u5834\u5408<span>println<\/span>\u30e1\u30bd\u30c3\u30c9\u3067\u306f\u5f15\u6570\u304c<span>String<\/span>\u578b\u540c\u58eb\u306e\u305f\u3081\u6587\u5b57\u5217\u9023\u7d50\u3055\u308c\u307e\u3059\u3002<\/p>\n<p>\u3053\u3053\u3067\u306e\u30dd\u30a4\u30f3\u30c8\u306f<span>int<\/span>\u578b\u306f\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u578b\u306e\u305f\u3081\u305d\u306e\u307e\u307e\u3067\u306f\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u3046\u3053\u3068\u304c\u3067\u304d\u307e\u305b\u3093\u3002<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u3067<span>String<\/span>\u578b\u306b\u5909\u63db\u3059\u308b\u306b\u306f\u30e9\u30c3\u30d1\u30fc\u30af\u30e9\u30b9\u3067\u3042\u308b<span>Integer<\/span>\u30af\u30e9\u30b9\u304b\u3089\u30e1\u30bd\u30c3\u30c9\u3092\u547c\u3073\u51fa\u3059\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<p>\u4ee5\u4e0a\u304c<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u3063\u305f<span>int<\/span>\u578b\u306e<span>String<\/span>\u578b\u3078\u306e\u5909\u63db\u65b9\u6cd5\u3067\u3059\u3002<\/p>\n<p>\u203b<span>System.out.print<\/span>\u30e1\u30bd\u30c3\u30c9\u3067\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u578b\u3092\u5f15\u6570\u306b\u3057\u305f\u5834\u5408\u3082\u30e9\u30c3\u30d1\u30fc\u30af\u30e9\u30b9\u306e<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u3092\u7d4c\u3066\u51fa\u529b\u3055\u308c\u3066\u3044\u307e\u3059\u3002\uff08<span>+<\/span>\u6f14\u7b97\u5b50\u306b\u3088\u308b\u8a55\u4fa1\u306f\u30e1\u30bd\u30c3\u30c9\u5b9f\u884c\u524d\u306e\u305f\u3081\u3001\u5148\u306b<span>int<\/span>\u578b\u3068\u3057\u3066\u8db3\u3057\u7b97\u3055\u308c\u307e\u3059\uff09\u30e9\u30c3\u30d1\u30fc\u30af\u30e9\u30b9\u306f\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u578b\u3092\u53c2\u7167\u578b\u3068\u3057\u3066\u6271\u3046\u305f\u3081\u306e\u30af\u30e9\u30b9\u3067\u3059\u3002\u4ed6\u306e\u30d7\u30ea\u30df\u30c6\u30a3\u30d6\u578b\u306b\u3082\u305d\u308c\u305e\u308c\u30e9\u30c3\u30d1\u30fc\u30af\u30e9\u30b9\u304c\u7528\u610f\u3055\u308c\u3066\u3044\u308b\u306e\u3067\u3001\u6c17\u306b\u306a\u308b\u65b9\u306f\u8abf\u3079\u3066\u307f\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n<h2><span id=\"JavatoString-2\">\uff12\uff0e\u3010Java\u3011\u81ea\u4f5c\u30af\u30e9\u30b9\u306etoString\u30e1\u30bd\u30c3\u30c9\u306f\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3057\u3088\u3046<\/span><\/h2>\n<p>\u6b21\u306b\u3001\u81ea\u4f5c\u30af\u30e9\u30b9\u3067<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u3092\u610f\u56f3\u3057\u3066\u4f7f\u3046\u306b\u306f\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3092\u3059\u308b\u5fc5\u8981\u304c\u3042\u308b\u3001\u3068\u3044\u3046\u3053\u3068\u3092\u898b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">package example;\r\n\r\npublic class Dog {\r\n\tString name;\r\n\tint age;\r\n\tString kind;\r\n\r\n\tpublic Dog() {\r\n\t\tthis.name = \"\u30dd\u30c1\";\r\n\t\tthis.age = 3;\r\n\t\tthis.kind = \"\u30c1\u30ef\u30ef\";\r\n\t}\r\n}\r\n<\/pre>\n<p>\u4e0a\u8a18\u306e\u3088\u3046\u306a\u81ea\u4f5c\u30af\u30e9\u30b9\u3092\u7528\u610f\u3057\u3066\u3001<span>main<\/span>\u30e1\u30bd\u30c3\u30c9\u3067\u4ee5\u4e0b\u3092\u5b9f\u884c\u3057\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">Dog dog = new Dog();\r\nSystem.out.println(dog);\r\n<\/pre>\n<p>\u7d50\u679c\u306f\u4ee5\u4e0b\u3067\u3059\u3002<\/p>\n<p>\uff0d\uff0d\uff0d<br \/>\n<span><a href=\"mailto:example.Dog@48140564\">example.Dog@48140564<\/a><br \/>\n<\/span>\uff0d\uff0d\uff0d<\/p>\n<p>Dog\u30af\u30e9\u30b9\u3092\u6587\u5b57\u5217\u3067\u51fa\u529b\u3057\u305f\u3044\u306e\u306b\u3001\u4e00\u898b\u3057\u3066\u610f\u5473\u306e\u308f\u304b\u3089\u306a\u3044\u7d50\u679c\u304c\u51fa\u529b\u3055\u308c\u307e\u3057\u305f\u3002\u3053\u3053\u3067\u3001<span>1-1<\/span>\u3067\u7d39\u4ecb\u3057\u305f<span>Object<\/span>\u30af\u30e9\u30b9\u306e<span>API<\/span>\u3067\u5b9a\u7fa9\u3055\u308c\u3066\u3044\u308b<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u306e\u5185\u5bb9\u3092\u601d\u3044\u51fa\u3057\u3066\u304f\u3060\u3055\u3044\u3002\u6ce8\u76ee\u3059\u308b\u306e\u306f\u4ee5\u4e0b\u306e\u90e8\u5206\u3067\u3059\u3002<\/p>\n<p><strong>\u30af\u30e9\u30b9<span>Object<\/span>\u306e<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304c\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u306b\u306a\u3063\u3066\u3044\u308b\u5143\u306e\u30af\u30e9\u30b9\u306e\u540d\u524d\u3001\u30a2\u30c3\u30c8\u30de\u30fc\u30af\u6587\u5b57\u300c<span>@<\/span>\u300d\u3001\u304a\u3088\u3073\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u30cf\u30c3\u30b7\u30e5\u30fb\u30b3\u30fc\u30c9\u306e\u7b26\u53f7\u306a\u3057<span>16<\/span>\u9032\u6570\u8868\u73fe\u304b\u3089\u69cb\u6210\u3055\u308c\u308b\u6587\u5b57\u5217\u3092\u8fd4\u3057\u307e\u3059\u3002 \u3064\u307e\u308a\u3001\u3053\u306e\u30e1\u30bd\u30c3\u30c9\u306f\u6b21\u306e\u5024\u3068\u7b49\u3057\u3044\u6587\u5b57\u5217\u3092\u8fd4\u3057\u307e\u3059\u3002<\/strong><\/p>\n<p><strong>\u00a0<\/strong><strong>\u00a0getClass().getName() + &#8216;@&#8217; + Integer.toHexString(hashCode())<\/strong><\/p>\n<p>\u3064\u307e\u308a\u81ea\u4f5c\u30af\u30e9\u30b9\u3067<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u304c\u547c\u3073\u51fa\u3055\u308c\u308b\u3068\u304d\u306b\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3057\u3066\u3044\u306a\u3044\u5834\u5408\u306f\u7d99\u627f\u5143\u3067\u3042\u308b<span>Object<\/span>\u30af\u30e9\u30b9\u306e<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u304c\u547c\u3073\u51fa\u3055\u308c\u308b\u305f\u3081\u3001\u610f\u56f3\u3057\u306a\u3044\u6587\u5b57\u5217\u304c\u51fa\u529b\u3055\u308c\u3066\u3057\u307e\u3046\u306e\u3067\u3059\u3002API\u306b\u300c\u3053\u306e\u30e1\u30bd\u30c3\u30c9\u3092\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3059\u308b\u3053\u3068\u3092\u304a\u52e7\u3081\u3057\u307e\u3059\u3002\u300d\u3068\u66f8\u304b\u308c\u3066\u3044\u308b\u306e\u306f\u3053\u306e\u305f\u3081\u3067\u3059\u3002<\/p>\n<p>\u81ea\u4f5c\u30af\u30e9\u30b9\u3067<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3057\u3066\u610f\u56f3\u3057\u305f\u6587\u5b57\u5217\u3092\u51fa\u529b\u3057\u305f\u3044\u306e\u306a\u3089\u3001\u304d\u3061\u3093\u3068\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3057\u3066\u51fa\u529b\u3057\u305f\u3044\u5185\u5bb9\u3092\u5b9f\u88c5\u3059\u308b\u5fc5\u8981\u304c\u3042\u308b\u3088\u3001\u305d\u3046\u3067\u306a\u304d\u3083\u3068\u308a\u3042\u3048\u305a<span>Object<\/span>\u30af\u30e9\u30b9\u3067\u5b9a\u7fa9\u3057\u3066\u3044\u308b\u5185\u5bb9\u3067\u51fa\u529b\u3057\u3068\u304f\u306d\u3001\u3068\u3044\u3046\u3053\u3068\u3067\u3059\u3002<\/p>\n<p>\u305d\u308c\u3067\u306f\u3001\u5148\u307b\u3069\u306e<span>Dog<\/span>\u30af\u30e9\u30b9\u3067<span>toString<\/span>\u30af\u30e9\u30b9\u3092\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002Dog\u30af\u30e9\u30b9\u306b\u4ee5\u4e0b\u306e\u30b3\u30fc\u30c9\u3092\u8ffd\u52a0\u3057\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">@Override\r\npublic String toString() {\r\n\treturn \"Dog [name=\" + name + \", age=\" + age + \", kind=\" + kind + \"]\";\r\n}\r\n<\/pre>\n<p>\u305d\u3057\u3066\u3001\u518d\u3073<span>main<\/span>\u30e1\u30bd\u30c3\u30c9\u3067\u4ee5\u4e0b\u3092\u5b9f\u884c\u3057\u307e\u3059\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">Dog dog = new Dog();\r\nSystem.out.println(dog);\r\n<\/pre>\n<p>\u3059\u308b\u3068\u7d50\u679c\u306f\u4ee5\u4e0b\u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n<p>\uff0d\uff0d\uff0d<br \/>\nDog [name=\u30dd\u30c1<span>, age=3, kind=<\/span>\u30c1\u30ef\u30ef<span>]<br \/>\n<\/span>\uff0d\uff0d\uff0d<\/p>\n<p>Dog\u30af\u30e9\u30b9\u3067\u5b9a\u7fa9\u3057\u305f<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u306e\u5185\u5bb9\u304c\u51fa\u529b\u3055\u308c\u307e\u3057\u305f\u3002\u3053\u306e\u3088\u3046\u306b\u81ea\u4f5c\u30af\u30e9\u30b9\u3067\u306f<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u3092\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3059\u308b\u3053\u3068\u3067\u610f\u56f3\u3057\u305f\u6587\u5b57\u5217\u3092\u51fa\u529b\u3067\u304d\u308b\u3053\u3068\u304c\u304a\u308f\u304b\u308a\u3044\u305f\u3060\u3051\u305f\u304b\u3068\u601d\u3044\u307e\u3059\u3002\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u77e5\u308a\u305f\u3044\u65b9\u306f\u4ee5\u4e0b\u306e\u8a18\u4e8b\u3092\u53c2\u8003\u306b\u3057\u3066\u307f\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n\n<span style=\"text-decoration:none !important; background-color:#a61e58; color:white; padding:4px 13px; font-size:12px; font-weight:bold; position:relative; top:10px; z-index:1; left:11px;\">\u95a2\u9023\u8a18\u4e8b<\/span>\n<div class=\"blog-card\"><a target=\"_blank\" href=\"https:\/\/www.bold.ne.jp\/engineer-club\/java-override\" style=\"text-decoration:none;\">\n    <div class=\"blog-card-thumbnail\"><img src='https:\/\/www.bold.ne.jp\/engineer-club\/wp-content\/uploads\/2018\/10\/shutterstock_568617811-600x366.jpg' alt='Java\u306e\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3068\u306f\uff1f\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3068\u307f\u306a\u3055\u308c\u308b\u6761\u4ef6\u3084\u4f7f\u3044\u65b9' width=160 height=98 \/><\/div>\n    <div class=\"blog-card-content\">\n        <div class=\"blog-card-title\">Java\u306e\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3068\u306f\uff1f\u30aa\u30fc\u30d0\u30fc\u30e9\u30a4\u30c9\u3068\u307f\u306a\u3055\u308c\u308b\u6761\u4ef6\u3084\u4f7f\u3044\u65b9 <\/div>\n        <span style=\"font-size: 12px; font-weight: normal; position:relative; color:#666;\"><i class=\"fa fa-clock-o\"><\/i>&nbsp;2025\/10\/06<\/span>\n    <\/div>\n<div class=\"clear\"><\/div>\n<\/a><\/div>\n<h2><span id=\"JavatoStringvalueOf\">\uff13\uff0e\u3010Java\u3011toString\u30e1\u30bd\u30c3\u30c9\u306e\u6ce8\u610f\u70b9\u3001valueOf\u30e1\u30bd\u30c3\u30c9\u3068\u306e\u9055\u3044<\/span><\/h2>\n<p>toString\u3092\u4f7f\u7528\u3059\u308b\u4e0a\u3067\u306e\u6ce8\u610f\u70b9\u3068\u3057\u3066\u306f\u3001<span>null<\/span>\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u5909\u63db\u3057\u3088\u3046\u3068\u3059\u308b\u3068<span>NullPointerException<\/span>\u304c\u767a\u751f\u3057\u3066\u3057\u307e\u3046\u3053\u3068\u304c\u6319\u3052\u3089\u308c\u307e\u3059\u3002<span>null<\/span>\u30c1\u30a7\u30c3\u30af\u3092\u884c\u3046\u304b<span>null<\/span>\u3067\u306a\u3044\u3053\u3068\u304c\u4fdd\u8a3c\u3067\u304d\u308b\u72b6\u614b\u304b\u3089\u547c\u3073\u51fa\u3059\u3088\u3046\u306b\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<p>\u5177\u4f53\u7684\u306b\u898b\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n<pre class=\"prettyprint lang:default decode:true\">Dog dog = null;\r\nSystem.out.println(dog);\r\nString strDog = dog.toString();\r\nSystem.out.println(strDog);\r\n<\/pre>\n<p>\u7d50\u679c\u306f\u4ee5\u4e0b\u3067\u3059\u3002<\/p>\n<p>\uff0d\uff0d\uff0d<br \/>\nnull<br \/>\n<span style=\"color: #ff0000;\">Exception in thread &#8220;main&#8221;<\/span> <span style=\"color: #0000ff;\"><u>java.lang.NullPointerException<br \/>\n<\/u><\/span>\u00a0\u00a0\u00a0 <span style=\"color: #ff0000;\">at sample\/example.Main.main<\/span><span style=\"color: #0000ff;\">(Main.java:9)<br \/>\n<\/span>\uff0d\uff0d\uff0d<\/p>\n<p>\u884c\u6570\u304c\u306a\u3044\u306e\u3067\u308f\u304b\u308a\u306b\u304f\u3044\u3067\u3059\u304c\u3001\u6700\u521d\u306e<span>println<\/span>\u30e1\u30bd\u30c3\u30c9\u3067\u306f<span>null<\/span>\u304c\u51fa\u529b\u3055\u308c\u6b21\u306e\u884c\u306e<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u306e\u547c\u3073\u51fa\u3057\u3067<span>NullPointerException<\/span>\u304c\u767a\u751f\u3057\u3066\u3044\u307e\u3059\u3002\uff08<span>2<\/span>\u56de\u76ee\u306e<span>println<\/span>\u30e1\u30bd\u30c3\u30c9\u306f\u5b9f\u884c\u3055\u308c\u306a\u3044\uff09<\/p>\n<p>\u3053\u3053\u3067\u6ce8\u76ee\u3057\u305f\u3044\u306e\u306f\u3001<span>NullPointerException<\/span>\u304c\u767a\u751f\u3059\u308b\u306e\u306f\u3001<br \/>\nSystem.out.println(dog);<br \/>\n\u3067\u306f\u306a\u304f\u3001<br \/>\nString strDog = dog.toString();<br \/>\n\u3067\u3042\u308b\u3068\u3044\u3046\u70b9\u3067\u3059\u3002<\/p>\n<p>\u3053\u3053\u3067\u300c<span>println<\/span>\u30e1\u30bd\u30c3\u30c9\u306f\u5185\u90e8\u3067<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u304c\u547c\u3073\u51fa\u3055\u308c\u3066\u3044\u308b\u306f\u305a\u3067\u306f\uff1f\u300d\u3068\u601d\u3063\u305f\u65b9\u306f\u92ed\u3044\u3067\u3059\uff01<\/p>\n<p>1-2\u3067<span>print<\/span>\u30e1\u30bd\u30c3\u30c9\u3084<span>println<\/span>\u30e1\u30bd\u30c3\u30c9\u3067\u306f\u5185\u90e8\u3067<span>String.valueOf<\/span>\u30e1\u30bd\u30c3\u30c9\u304c\u547c\u3073\u51fa\u3055\u308c\u3001<span>valueOf<\/span>\u30e1\u30bd\u30c3\u30c9\u304b\u3089<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u3092\u547c\u3073\u51fa\u3059\u3068\u3044\u3044\u307e\u3057\u305f\u3002\u5b9f\u306f<span>String.valueOf<\/span>\u30e1\u30bd\u30c3\u30c9\u3067\u306f\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304c<span>null<\/span>\u304b\u3069\u3046\u304b\u3092\u5224\u5b9a\u3057\u3001<span>null<\/span>\u306e\u5834\u5408\u306f\u6587\u5b57\u5217\u306e<span>\u201dnull\u201d<\/span>\u3001\u305d\u3046\u3067\u306a\u3044\u5834\u5408\u306f<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u3092\u547c\u3073\u51fa\u3059\u3088\u3046\u306b\u306a\u3063\u3066\u3044\u307e\u3059\u3002\u305d\u306e\u305f\u3081<span>System.out.println(dog);<\/span>\u306e\u884c\u3067\u306f\u305d\u3082\u305d\u3082<span>toString<\/span>\u30e1\u30bd\u30c3\u30c9\u306f\u547c\u3073\u51fa\u3055\u308c\u3066\u3044\u306a\u3044\u306e\u3067\u3059\u3002<\/p>\n<p>String.valueOf\u30e1\u30bd\u30c3\u30c9\u3082\u69d8\u3005\u306a\u578b\u3092<span>String<\/span>\u578b\u306b\u5909\u63db\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002toString\u30e1\u30bd\u30c3\u30c9\u3068\u7528\u9014\u306f\u4f3c\u3066\u3044\u307e\u3059\u304c\u4e21\u8005\u3067\u306f<span>null<\/span>\u306b\u5bfe\u3059\u308b\u52d5\u4f5c\u306e\u9055\u3044\u304c\u3042\u308b\u3053\u3068\u3092\u899a\u3048\u3066\u304a\u3044\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n<p>\uff14\uff0e\u307e\u3068\u3081<\/p>\n<p>toString\u30e1\u30bd\u30c3\u30c9\u306e\u4f7f\u3044\u65b9\u304c\u308f\u304b\u308c\u3070\u81ea\u4f5c\u30af\u30e9\u30b9\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u4e2d\u8eab\u3092\u78ba\u8a8d\u3059\u308b\u3053\u3068\u3082\u81ea\u5728\u306b\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<p>\u4ed5\u7d44\u307f\u3055\u3048\u7406\u89e3\u3057\u3066\u3057\u307e\u3048\u3070\u3055\u307b\u3069\u96e3\u3057\u304f\u306a\u3044\u306e\u3067\u305c\u3072\u3053\u306e\u6a5f\u4f1a\u306b\u81ea\u5206\u306e\u3082\u306e\u306b\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n","protected":false},"excerpt":{"rendered":"<p>toString\u30e1\u30bd\u30c3\u30c9\u306f\u6587\u5b57\u5217\u306b\u5909\u63db\u3059\u308b\u969b\u306b\u4f7f\u7528\u3059\u308b\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u3002 \u6570\u5024\u578b\u3084\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u4e2d\u8eab\u3092\u6587\u5b57\u5217\u3068\u3057\u3066\u53d6\u5f97\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002 \u305f\u3060\u3057\u81ea\u4f5c\u30af\u30e9\u30b9\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u5834\u5408\u3001\u4e2d\u8eab\u3092\u610f\u56f3\u3057\u305f\u6587\u5b57\u5217\u3068\u3057\u3066\u53d6\u5f97\u3059\u308b\u306b\u306f\u30aa\u30fc\u30d0\u30fc [&hellip;]<\/p>\n","protected":false},"author":9,"featured_media":3232,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[14],"acf":[],"_links":{"self":[{"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/posts\/3229"}],"collection":[{"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/users\/9"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/comments?post=3229"}],"version-history":[{"count":8,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/posts\/3229\/revisions"}],"predecessor-version":[{"id":6073,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/posts\/3229\/revisions\/6073"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/media\/3232"}],"wp:attachment":[{"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/media?parent=3229"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bold.ne.jp\/engineer-club\/wp-json\/wp\/v2\/categories?post=3229"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}