{"id":479015,"date":"2023-08-09T10:01:33","date_gmt":"2023-08-09T10:01:33","guid":{"rendered":""},"modified":"2023-09-05T11:18:01","modified_gmt":"2023-09-05T11:18:01","slug":"singleton-variable","status":"publish","type":"wiki","link":"https:\/\/oneproxy.pro\/jp\/wiki\/singleton-variable\/","title":{"rendered":"\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570"},"content":{"rendered":"<h2>\u5c0e\u5165<\/h2>\n<p>\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570\u306f\u3001\u30af\u30e9\u30b9\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u5316\u3092 1 \u3064\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u5236\u9650\u3059\u308b\u305f\u3081\u306b\u4f7f\u7528\u3055\u308c\u308b\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u6982\u5ff5\u3067\u3059\u3002\u8a00\u3044\u63db\u3048\u308c\u3070\u3001\u30d7\u30ed\u30b0\u30e9\u30e0\u306e\u5b9f\u884c\u5168\u4f53\u3092\u901a\u3058\u3066\u3001\u30af\u30e9\u30b9\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c 1 \u3064\u3060\u3051\u5b58\u5728\u3059\u308b\u3053\u3068\u304c\u4fdd\u8a3c\u3055\u308c\u307e\u3059\u3002\u3053\u306e\u8a2d\u8a08\u30d1\u30bf\u30fc\u30f3\u306f\u3001\u5171\u6709\u30ea\u30bd\u30fc\u30b9\u3078\u306e\u30b0\u30ed\u30fc\u30d0\u30eb \u30a2\u30af\u30bb\u30b9 \u30dd\u30a4\u30f3\u30c8\u304c 1 \u3064\u3060\u3051\u5fc5\u8981\u306a\u5834\u5408\u3001\u307e\u305f\u306f\u30b7\u30b9\u30c6\u30e0 \u30ea\u30bd\u30fc\u30b9\u3092\u7bc0\u7d04\u3059\u308b\u305f\u3081\u306b\u30af\u30e9\u30b9\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u306e\u6570\u3092\u5236\u5fa1\u3059\u308b\u5fc5\u8981\u304c\u3042\u308b\u5834\u5408\u306b\u7279\u306b\u5f79\u7acb\u3061\u307e\u3059\u3002<\/p>\n<h2>\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570\u306e\u6b74\u53f2\u3068\u8d77\u6e90<\/h2>\n<p>\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3 \u30c7\u30b6\u30a4\u30f3 \u30d1\u30bf\u30fc\u30f3\u306f\u30011994 \u5e74\u306b\u51fa\u7248\u3055\u308c\u305f\u5f71\u97ff\u529b\u306e\u3042\u308b\u66f8\u7c4d\u300e\u30c7\u30b6\u30a4\u30f3 \u30d1\u30bf\u30fc\u30f3: \u518d\u5229\u7528\u53ef\u80fd\u306a\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u6307\u5411\u30bd\u30d5\u30c8\u30a6\u30a7\u30a2\u306e\u8981\u7d20\u300f\u306e\u4e2d\u3067\u3001Gang of Four (GoF) \u306b\u3088\u3063\u3066\u521d\u3081\u3066\u5c0e\u5165\u3055\u308c\u307e\u3057\u305f\u3002\u5f7c\u3089\u306f\u3001\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3 \u30d1\u30bf\u30fc\u30f3\u3092\u3001\u5358\u4e00\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3092\u4f5c\u6210\u3059\u308b\u305f\u3081\u306b\u4f7f\u7528\u3055\u308c\u308b\u4f5c\u6210\u30d1\u30bf\u30fc\u30f3\u3068\u3057\u3066\u63d0\u793a\u3057\u307e\u3057\u305f\u3002\u30b0\u30ed\u30fc\u30d0\u30eb\u306b\u30a2\u30af\u30bb\u30b9\u53ef\u80fd\u3067\u3042\u308a\u3001\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u5168\u4f53\u3067\u5171\u6709\u3055\u308c\u308b\u30af\u30e9\u30b9\u3002<\/p>\n<h2>\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570\u306e\u8a73\u7d30\u60c5\u5831<\/h2>\n<p>\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570\u306f\u3001\u30d7\u30e9\u30a4\u30d9\u30fc\u30c8 \u30b3\u30f3\u30b9\u30c8\u30e9\u30af\u30bf\u30fc\u3068\u30af\u30e9\u30b9\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3092\u8fd4\u3059\u9759\u7684\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3057\u3066\u30af\u30e9\u30b9\u3092\u5b9a\u7fa9\u3059\u308b\u3053\u3068\u306b\u3088\u3063\u3066\u5b9f\u88c5\u3055\u308c\u307e\u3059\u3002\u3053\u306e\u9759\u7684\u30e1\u30bd\u30c3\u30c9\u306b\u3088\u308a\u3001\u547c\u3073\u51fa\u3055\u308c\u305f\u56de\u6570\u306b\u95a2\u4fc2\u306a\u304f\u3001\u30af\u30e9\u30b9\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c 1 \u3064\u3060\u3051\u4f5c\u6210\u3055\u308c\u3066\u8fd4\u3055\u308c\u307e\u3059\u3002\u5f8c\u7d9a\u306e\u9759\u7684\u30e1\u30bd\u30c3\u30c9\u306e\u547c\u3073\u51fa\u3057\u3067\u306f\u3001\u5e38\u306b\u540c\u3058\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c\u8fd4\u3055\u308c\u307e\u3059\u3002<\/p>\n<h2>\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570\u306e\u5185\u90e8\u69cb\u9020\u3068\u305d\u306e\u4ed5\u7d44\u307f<\/h2>\n<p>\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570\u306e\u5185\u90e8\u69cb\u9020\u306f\u6bd4\u8f03\u7684\u5358\u7d14\u3067\u3059\u3002\u901a\u5e38\u3001\u6b21\u306e\u30b3\u30f3\u30dd\u30fc\u30cd\u30f3\u30c8\u3067\u69cb\u6210\u3055\u308c\u307e\u3059\u3002<\/p>\n<ol>\n<li>\n<p><strong>\u30d7\u30e9\u30a4\u30d9\u30fc\u30c8\u30b3\u30f3\u30b9\u30c8\u30e9\u30af\u30bf\u30fc:<\/strong> \u3053\u306e\u30af\u30e9\u30b9\u306b\u306f\u3001\u300cnew\u300d\u30ad\u30fc\u30ef\u30fc\u30c9\u3092\u4f7f\u7528\u3057\u3066\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u76f4\u63a5\u4f5c\u6210\u3067\u304d\u306a\u3044\u3088\u3046\u306b\u3059\u308b\u305f\u3081\u306e\u30d7\u30e9\u30a4\u30d9\u30fc\u30c8 \u30b3\u30f3\u30b9\u30c8\u30e9\u30af\u30bf\u30fc\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u308c\u306f\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u30af\u30e9\u30b9\u306e\u5916\u90e8\u304b\u3089\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u5316\u3067\u304d\u306a\u3044\u3053\u3068\u3092\u610f\u5473\u3057\u307e\u3059\u3002<\/p>\n<\/li>\n<li>\n<p><strong>\u9759\u7684\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u30e1\u30bd\u30c3\u30c9:<\/strong> \u30af\u30e9\u30b9\u306b\u306f\u3001\u30af\u30e9\u30b9\u306e\u5358\u4e00\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3078\u306e\u30a2\u30af\u30bb\u30b9\u3092\u63d0\u4f9b\u3059\u308b\u9759\u7684\u30e1\u30bd\u30c3\u30c9\u304c\u542b\u307e\u308c\u3066\u3044\u307e\u3059\u3002\u3053\u306e\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c\u5b58\u5728\u3057\u306a\u3044\u5834\u5408\u306f\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3092\u4f5c\u6210\u3057\u3001\u5b58\u5728\u3059\u308b\u5834\u5408\u306f\u65e2\u5b58\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3092\u8fd4\u3059\u5f79\u5272\u3092\u62c5\u3044\u307e\u3059\u3002<\/p>\n<\/li>\n<\/ol>\n<h2>\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570\u306e\u4e3b\u306a\u6a5f\u80fd\u306e\u5206\u6790<\/h2>\n<ol>\n<li>\n<p><strong>\u30b0\u30ed\u30fc\u30d0\u30eb \u30dd\u30a4\u30f3\u30c8 \u30aa\u30d6 \u30a2\u30af\u30bb\u30b9:<\/strong> \u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570\u306f\u3001\u5171\u6709\u30ea\u30bd\u30fc\u30b9\u307e\u305f\u306f\u6a5f\u80fd\u3078\u306e\u30b0\u30ed\u30fc\u30d0\u30eb \u30a2\u30af\u30bb\u30b9 \u30dd\u30a4\u30f3\u30c8\u3092\u63d0\u4f9b\u3057\u3001\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306e\u3055\u307e\u3056\u307e\u306a\u90e8\u5206\u304c\u540c\u3058\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u306b\u30a2\u30af\u30bb\u30b9\u3067\u304d\u308b\u3088\u3046\u306b\u3057\u307e\u3059\u3002<\/p>\n<\/li>\n<li>\n<p><strong>\u30e1\u30e2\u30ea\u52b9\u7387:<\/strong> \u30af\u30e9\u30b9\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c 1 \u3064\u3060\u3051\u4f5c\u6210\u3055\u308c\u3066\u518d\u5229\u7528\u3055\u308c\u308b\u305f\u3081\u3001\u30e1\u30e2\u30ea \u30ea\u30bd\u30fc\u30b9\u304c\u7bc0\u7d04\u3055\u308c\u3001\u4e0d\u5fc5\u8981\u306a\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u4f5c\u6210\u304c\u9632\u6b62\u3055\u308c\u307e\u3059\u3002<\/p>\n<\/li>\n<li>\n<p><strong>\u30b9\u30ec\u30c3\u30c9\u306e\u5b89\u5168\u6027:<\/strong> \u9069\u5207\u306b\u5b9f\u88c5\u3055\u308c\u305f\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3 \u30d1\u30bf\u30fc\u30f3\u306f\u30b9\u30ec\u30c3\u30c9\u30bb\u30fc\u30d5\u3067\u3042\u308a\u3001\u8907\u6570\u306e\u30b9\u30ec\u30c3\u30c9\u304c\u8907\u6570\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3092\u540c\u6642\u306b\u4f5c\u6210\u3067\u304d\u306a\u3044\u3088\u3046\u306b\u3057\u307e\u3059\u3002<\/p>\n<\/li>\n<li>\n<p><strong>\u9045\u5ef6\u521d\u671f\u5316:<\/strong> \u30b7\u30f3\u30b0\u30eb\u30c8\u30f3 \u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u306f\u9045\u5ef6\u7684\u306b\u4f5c\u6210\u3067\u304d\u307e\u3059\u3002\u3064\u307e\u308a\u3001\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u306f getInstance() \u30e1\u30bd\u30c3\u30c9\u304c\u521d\u3081\u3066\u547c\u3073\u51fa\u3055\u308c\u305f\u3068\u304d\u306b\u306e\u307f\u4f5c\u6210\u3055\u308c\u307e\u3059\u3002<\/p>\n<\/li>\n<\/ol>\n<h2>\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570\u306e\u7a2e\u985e<\/h2>\n<p>\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570\u306e\u5b9f\u88c5\u306b\u306f\u4e3b\u306b 2 \u3064\u306e\u30bf\u30a4\u30d7\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<ol>\n<li>\n<p><strong>\u71b1\u5fc3\u306a\u521d\u671f\u5316:<\/strong> \u3053\u306e\u30a2\u30d7\u30ed\u30fc\u30c1\u3067\u306f\u3001\u30d7\u30ed\u30b0\u30e9\u30e0\u3067\u3059\u3050\u306b\u4f7f\u7528\u3055\u308c\u306a\u3044\u5834\u5408\u3067\u3082\u3001\u30af\u30e9\u30b9\u306e\u30ed\u30fc\u30c9\u6642\u306b\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c\u4f5c\u6210\u3055\u308c\u307e\u3059\u3002<\/p>\n<\/li>\n<li>\n<p><strong>\u9045\u5ef6\u521d\u671f\u5316:<\/strong> \u3053\u3053\u3067\u3001\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u306f getInstance() \u30e1\u30bd\u30c3\u30c9\u306b\u3088\u3063\u3066\u6700\u521d\u306b\u8981\u6c42\u3055\u308c\u305f\u3068\u304d\u306b\u306e\u307f\u4f5c\u6210\u3055\u308c\u307e\u3059\u3002\u9045\u5ef6\u521d\u671f\u5316\u306f\u3001\u540c\u671f\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3059\u308b\u304b\u3001\u30b9\u30ec\u30c3\u30c9\u306e\u5b89\u5168\u6027\u3092\u78ba\u4fdd\u3059\u308b\u305f\u3081\u306b\u4e8c\u91cd\u30c1\u30a7\u30c3\u30af\u3055\u308c\u305f\u30ed\u30c3\u30af\u3092\u4f7f\u7528\u3057\u3066\u5b9f\u884c\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/li>\n<\/ol>\n<p>\u8868\u3092\u4f7f\u7528\u3057\u3066 2 \u3064\u306e\u30bf\u30a4\u30d7\u3092\u6bd4\u8f03\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n<table>\n<thead>\n<tr>\n<th><\/th>\n<th>\u7a4d\u6975\u7684\u306a\u521d\u671f\u5316<\/th>\n<th>\u9045\u5ef6\u521d\u671f\u5316<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>\u9577\u6240<\/td>\n<td>&ndash; \u30b9\u30ec\u30c3\u30c9\u306e\u5b89\u5168\u6027\u3092\u4fdd\u8a3c&lt;br&gt;- \u30b7\u30f3\u30d7\u30eb\u306a\u5b9f\u88c5<\/td>\n<td>&ndash; \u5fc5\u8981\u306a\u5834\u5408\u306b\u306e\u307f\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3092\u4f5c\u6210\u3059\u308b\u3053\u3068\u3067\u30e1\u30e2\u30ea\u3092\u7bc0\u7d04\u3057\u307e\u3059&lt;br&gt;- \u30ea\u30bd\u30fc\u30b9\u3092\u5927\u91cf\u306b\u6d88\u8cbb\u3059\u308b\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u9069\u3057\u3066\u3044\u307e\u3059<\/td>\n<\/tr>\n<tr>\n<td>\u77ed\u6240<\/td>\n<td>&ndash; \u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c\u3059\u3050\u306b\u4f7f\u7528\u3055\u308c\u306a\u3044\u5834\u5408\u3067\u3082\u30e1\u30e2\u30ea\u3092\u6d88\u8cbb\u3057\u307e\u3059&lt;br&gt;- \u30ea\u30bd\u30fc\u30b9\u306e\u591a\u3044\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u306f\u9069\u3057\u3066\u3044\u307e\u305b\u3093<\/td>\n<td>&ndash; \u30b9\u30ec\u30c3\u30c9\u30bb\u30fc\u30d5\u306e\u305f\u3081\u306b\u540c\u671f\u30a2\u30af\u30bb\u30b9\u304c\u5fc5\u8981&lt;br&gt;- \u3082\u3046\u5c11\u3057\u8907\u96d1\u306a\u5b9f\u88c5<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570\u306e\u4f7f\u7528\u65b9\u6cd5\u3001\u554f\u984c\u3001\u304a\u3088\u3073\u89e3\u6c7a\u7b56<\/h2>\n<h3>\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570\u306e\u4f7f\u7528\u65b9\u6cd5:<\/h3>\n<ol>\n<li>\n<p><strong>\u69cb\u6210\u7ba1\u7406:<\/strong> \u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570\u3092\u5229\u7528\u3057\u3066\u3001\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306e\u69cb\u6210\u8a2d\u5b9a\u3092\u7ba1\u7406\u3067\u304d\u307e\u3059\u3002\u5358\u4e00\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u306b\u3088\u308a\u3001\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u5168\u4f53\u3067\u4e00\u8cab\u3057\u305f\u8a2d\u5b9a\u304c\u4fdd\u8a3c\u3055\u308c\u307e\u3059\u3002<\/p>\n<\/li>\n<li>\n<p><strong>\u30ed\u30ac\u30fc\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9:<\/strong> \u30ed\u30ae\u30f3\u30b0\u306f\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306e\u4e00\u822c\u7684\u306a\u8981\u4ef6\u3067\u3059\u3002\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3 \u30ed\u30ac\u30fc \u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u306f\u3001\u30b7\u30b9\u30c6\u30e0\u306e\u3055\u307e\u3056\u307e\u306a\u90e8\u5206\u304b\u3089\u306e\u30ed\u30b0 \u30e1\u30c3\u30bb\u30fc\u30b8\u3092\u52b9\u7387\u7684\u306b\u7ba1\u7406\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/li>\n<\/ol>\n<h3>\u554f\u984c\u3068\u89e3\u6c7a\u7b56:<\/h3>\n<ol>\n<li>\n<p><strong>\u30de\u30eb\u30c1\u30b9\u30ec\u30c3\u30c9\u306e\u554f\u984c:<\/strong> \u6b63\u3057\u304f\u5b9f\u88c5\u3055\u308c\u3066\u3044\u306a\u3044\u5834\u5408\u3001\u8907\u6570\u306e\u30b9\u30ec\u30c3\u30c9\u306b\u3088\u3063\u3066 Singleton \u30af\u30e9\u30b9\u306e\u8907\u6570\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c\u4f5c\u6210\u3055\u308c\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u308c\u306f\u3001\u4e8c\u91cd\u30c1\u30a7\u30c3\u30af \u30ed\u30c3\u30af\u306a\u3069\u306e\u540c\u671f\u624b\u6cd5\u3092\u4f7f\u7528\u3059\u308b\u304b\u3001\u5217\u6319\u578b (Java \u306e\u5834\u5408) \u3092\u4f7f\u7528\u3057\u3066\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u306e\u4f5c\u6210\u3092\u6697\u9ed9\u7684\u306b\u51e6\u7406\u3059\u308b\u3053\u3068\u3067\u8efd\u6e1b\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/li>\n<li>\n<p><strong>\u5358\u4f53\u30c6\u30b9\u30c8:<\/strong> \u30b7\u30f3\u30b0\u30eb\u30c8\u30f3 \u30af\u30e9\u30b9\u306e\u30c6\u30b9\u30c8\u306f\u3001\u305d\u306e\u30b0\u30ed\u30fc\u30d0\u30eb\u306a\u6027\u8cea\u306b\u3088\u308a\u56f0\u96e3\u306b\u306a\u308b\u5834\u5408\u304c\u3042\u308a\u307e\u3059\u3002\u4f9d\u5b58\u95a2\u4fc2\u306e\u6ce8\u5165\u3092\u4f7f\u7528\u3059\u308b\u3068\u3001\u5358\u4f53\u30c6\u30b9\u30c8\u3092\u5bb9\u6613\u306b\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/li>\n<\/ol>\n<h2>\u4e3b\u306a\u7279\u5fb4\u3068\u985e\u4f3c\u7528\u8a9e\u3068\u306e\u6bd4\u8f03<\/h2>\n<p>\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u3092\u4ed6\u306e\u95a2\u9023\u7528\u8a9e\u3068\u6bd4\u8f03\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n<table>\n<thead>\n<tr>\n<th>\u5b66\u671f<\/th>\n<th>\u8aac\u660e<\/th>\n<th>\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u3068\u306e\u9055\u3044<\/th>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3<\/td>\n<td>\u30af\u30e9\u30b9\u3054\u3068\u306b 1 \u3064\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u306e\u8a2d\u8a08\u30d1\u30bf\u30fc\u30f3<\/td>\n<td>\u30af\u30e9\u30b9\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c 1 \u3064\u3060\u3051\u5b58\u5728\u3059\u308b\u3053\u3068\u3092\u4fdd\u8a3c\u3057\u307e\u3059<\/td>\n<\/tr>\n<tr>\n<td>\u9759\u7684\u30af\u30e9\u30b9<\/td>\n<td>\u9759\u7684\u30e1\u30f3\u30d0\u30fc\u3068\u30e1\u30bd\u30c3\u30c9\u3092\u542b\u3080\u30af\u30e9\u30b9<\/td>\n<td>\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u306f 1 \u3064\u306b\u9650\u3089\u305a\u3001\u8907\u6570\u5b58\u5728\u3059\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059<\/td>\n<\/tr>\n<tr>\n<td>\u30b0\u30ed\u30fc\u30d0\u30eb\u30aa\u30d6\u30b8\u30a7\u30af\u30c8<\/td>\n<td>\u30b3\u30fc\u30c9\u306e\u3069\u306e\u90e8\u5206\u304b\u3089\u3067\u3082\u30a2\u30af\u30bb\u30b9\u3067\u304d\u308b\u30aa\u30d6\u30b8\u30a7\u30af\u30c8<\/td>\n<td>\u30af\u30e9\u30b9\u306e\u5358\u4e00\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u5316\u3092\u5f37\u5236\u3067\u304d\u306a\u3044\u5834\u5408\u304c\u3042\u308a\u307e\u3059<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<h2>\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570\u306b\u95a2\u3059\u308b\u5c55\u671b\u3068\u5c06\u6765\u6280\u8853<\/h2>\n<p>\u30c7\u30b6\u30a4\u30f3 \u30d1\u30bf\u30fc\u30f3\u3068\u3057\u3066\u306e\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u306f\u3001\u7279\u306b\u30af\u30e9\u30b9\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c 1 \u3064\u3060\u3051\u5fc5\u8981\u306a\u5834\u5408\u306b\u3001\u30bd\u30d5\u30c8\u30a6\u30a7\u30a2\u958b\u767a\u306b\u304a\u3044\u3066\u4f9d\u7136\u3068\u3057\u3066\u8cb4\u91cd\u306a\u30c4\u30fc\u30eb\u3067\u3059\u3002\u5c06\u6765\u7684\u306b\u306f\u3001\u8a00\u8a9e\u6a5f\u80fd\u3068\u30c7\u30b6\u30a4\u30f3 \u30d1\u30bf\u30fc\u30f3\u306e\u6539\u5584\u306b\u3088\u308a\u3001\u540c\u69d8\u306e\u7d50\u679c\u3092\u9054\u6210\u3059\u308b\u305f\u3081\u306e\u3088\u308a\u6d17\u7df4\u3055\u308c\u305f\u65b9\u6cd5\u304c\u63d0\u4f9b\u3055\u308c\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002\u30c6\u30af\u30ce\u30ed\u30b8\u304c\u9032\u5316\u3059\u308b\u306b\u3064\u308c\u3066\u3001\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u306e\u95a2\u9023\u6027\u3068\u4f7f\u7528\u6cd5\u3082\u305d\u308c\u306b\u5fdc\u3058\u3066\u5909\u5316\u3059\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<h2>\u30d7\u30ed\u30ad\u30b7 \u30b5\u30fc\u30d0\u30fc\u306e\u4f7f\u7528\u65b9\u6cd5\u3001\u307e\u305f\u306f\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570\u3068\u306e\u95a2\u9023\u4ed8\u3051\u65b9\u6cd5<\/h2>\n<p>\u30cd\u30c3\u30c8\u30ef\u30fc\u30af\u901a\u4fe1\u3092\u7ba1\u7406\u3059\u308b\u305f\u3081\u306b\u5358\u4e00\u306e\u30d7\u30ed\u30ad\u30b7 \u30b5\u30fc\u30d0\u30fc \u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c\u5fc5\u8981\u306a\u30b7\u30ca\u30ea\u30aa\u3067\u306f\u3001\u30d7\u30ed\u30ad\u30b7 \u30b5\u30fc\u30d0\u30fc\u3068\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570\u3092\u95a2\u9023\u4ed8\u3051\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3 \u30d1\u30bf\u30fc\u30f3\u3067\u306f\u3001\u30d7\u30ed\u30ad\u30b7 \u30b5\u30fc\u30d0\u30fc \u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u304c\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u5168\u4f53\u3067\u78ba\u5b9f\u306b\u5171\u6709\u3055\u308c\u3001\u30ea\u30bd\u30fc\u30b9\u306e\u52b9\u7387\u7684\u306a\u5229\u7528\u3068\u96c6\u4e2d\u7ba1\u7406\u304c\u4fc3\u9032\u3055\u308c\u307e\u3059\u3002<\/p>\n<h2>\u95a2\u9023\u30ea\u30f3\u30af<\/h2>\n<p>\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u5909\u6570\u3068\u8a2d\u8a08\u30d1\u30bf\u30fc\u30f3\u306e\u8a73\u7d30\u306b\u3064\u3044\u3066\u306f\u3001\u6b21\u306e\u30ea\u30bd\u30fc\u30b9\u3092\u53c2\u7167\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n<ul>\n<li><a href=\"https:\/\/www.amazon.com\/Design-Patterns-Object-Oriented-Addison-Wesley-Professional\/dp\/0201633612\" target=\"_new\" rel=\"noopener nofollow\">\u30c7\u30b6\u30a4\u30f3\u30d1\u30bf\u30fc\u30f3: \u518d\u5229\u7528\u53ef\u80fd\u306a\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u6307\u5411\u30bd\u30d5\u30c8\u30a6\u30a7\u30a2\u306e\u8981\u7d20 (Amazon)<\/a><\/li>\n<li><a href=\"https:\/\/www.geeksforgeeks.org\/singleton-design-pattern\/\" target=\"_new\" rel=\"noopener nofollow\">\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3\u30d1\u30bf\u30fc\u30f3 \u2013 GeeksforGeeks<\/a><\/li>\n<li><a href=\"https:\/\/en.wikipedia.org\/wiki\/Singleton_pattern\" target=\"_new\" rel=\"noopener nofollow\">\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3 \u30d1\u30bf\u30fc\u30f3 \u2013 \u30a6\u30a3\u30ad\u30da\u30c7\u30a3\u30a2<\/a><\/li>\n<\/ul>\n<p>\u7d50\u8ad6\u3068\u3057\u3066\u3001Singleton \u5909\u6570\u306f\u3001\u30af\u30e9\u30b9\u306e\u30a4\u30f3\u30b9\u30bf\u30f3\u30b9\u3092 1 \u3064\u3060\u3051\u4f5c\u6210\u3059\u308b\u3053\u3068\u3092\u4fdd\u8a3c\u3057\u3001\u52b9\u7387\u7684\u306a\u30ea\u30bd\u30fc\u30b9\u7ba1\u7406\u3092\u4fc3\u9032\u3057\u3001\u5171\u6709\u30ea\u30bd\u30fc\u30b9\u3078\u306e\u30b0\u30ed\u30fc\u30d0\u30eb \u30a2\u30af\u30bb\u30b9 \u30dd\u30a4\u30f3\u30c8\u3092\u5bb9\u6613\u306b\u3059\u308b\u5f37\u529b\u306a\u8a2d\u8a08\u30d1\u30bf\u30fc\u30f3\u3067\u3059\u3002\u3053\u308c\u306f\u3055\u307e\u3056\u307e\u306a\u5206\u91ce\u3067\u5fdc\u7528\u3055\u308c\u3066\u304a\u308a\u3001\u30bd\u30d5\u30c8\u30a6\u30a7\u30a2\u958b\u767a\u306b\u304a\u3051\u308b\u8cb4\u91cd\u306a\u30c4\u30fc\u30eb\u3067\u3042\u308a\u7d9a\u3051\u3066\u3044\u307e\u3059\u3002\u30c6\u30af\u30ce\u30ed\u30b8\u30fc\u304c\u9032\u6b69\u3057\u3066\u3082\u3001\u30b7\u30f3\u30b0\u30eb\u30c8\u30f3 \u30d1\u30bf\u30fc\u30f3\u306f\u5f15\u304d\u7d9a\u304d\u95a2\u9023\u6027\u304c\u3042\u308a\u3001\u5805\u7262\u3067\u52b9\u7387\u7684\u306a\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3092\u4f5c\u6210\u3059\u308b\u305f\u3081\u306e\u57fa\u76e4\u3068\u3057\u3066\u6a5f\u80fd\u3057\u307e\u3059\u3002<\/p>","protected":false},"featured_media":470508,"menu_order":0,"template":"","meta":{"_acf_changed":false,"content-type":"","inline_featured_image":false,"footnotes":""},"class_list":["post-479015","wiki","type-wiki","status-publish","has-post-thumbnail","hentry"],"acf":{"faq_title":"Frequently Asked Questions about <mark>Singleton Variable: A Comprehensive Guide<\/mark>","faq_items":[{"question":"What is a Singleton variable?","answer":"<p>A Singleton variable is a programming concept used to restrict the instantiation of a class to one object. It ensures that only a single instance of the class exists throughout the program's execution, providing a global point of access to a shared resource or functionality.<\/p>"},{"question":"How did the Singleton variable originate?","answer":"<p>The Singleton design pattern was first introduced by the Gang of Four (GoF) in their influential book \"Design Patterns: Elements of Reusable Object-Oriented Software\" published in 1994. They presented the Singleton pattern as a creational pattern used to create a single instance of a class that is globally accessible and shared across the application.<\/p>"},{"question":"How does a Singleton variable work?","answer":"<p>The internal structure of a Singleton variable consists of a private constructor and a static method that returns the instance of the class. The static method ensures that only one instance of the class is created and returned, regardless of how many times it is called.<\/p>"},{"question":"What are the key features of a Singleton variable?","answer":"<p>The key features of a Singleton variable include:<\/p><ol><li>Global Point of Access: Singleton provides a single global point of access to a shared resource or functionality.<\/li><li>Memory Efficiency: It saves memory resources by reusing the same instance throughout the program.<\/li><li>Thread Safety: Properly implemented Singleton patterns are thread-safe, preventing multiple instances from being created concurrently.<\/li><li>Lazy Initialization: Singleton instances can be created lazily, i.e., the instance is created only when the getInstance() method is called for the first time.<\/li><\/ol>"},{"question":"What are the types of Singleton variable implementations?","answer":"<p>There are two main types of Singleton variable implementations:<\/p><ol><li>Eager Initialization: The instance is created at the time of class loading, even if it is not used immediately.<\/li><li>Lazy Initialization: The instance is created only when it is first requested by the getInstance() method. This can be done using synchronized methods or double-checked locking for thread safety.<\/li><\/ol>"},{"question":"How can Singleton variables be used?","answer":"<p>Singleton variables can be used in various scenarios, including:<\/p><ol><li>Configuration Management: Managing configuration settings for an application with a single, consistent instance.<\/li><li>Logger Instances: Efficiently managing log messages from different parts of the system with a centralized logger instance.<\/li><\/ol>"},{"question":"What are the potential problems with Singleton variables?","answer":"<p>Some potential problems include:<\/p><ol><li>Multithreading Issues: Improper implementation may lead to multiple instances being created by multiple threads.<\/li><li>Unit Testing: Testing Singleton classes can be challenging due to their global nature, but dependency injection can help facilitate testing.<\/li><\/ol>"},{"question":"How does a Singleton variable compare to other terms?","answer":"<p>Singleton differs from other terms like Static Class and Global Object. While a Singleton ensures only one instance of a class exists, a Static Class may have multiple instances, and a Global Object is accessible from any part of the code without enforcing single instantiation.<\/p>"},{"question":"What are the future perspectives related to Singleton variables?","answer":"<p>As technology advances, Singleton's relevance and usage might evolve. While the pattern remains valuable in software development, improvements in language features and design patterns may offer more elegant solutions in the future.<\/p>"},{"question":"How are proxy servers associated with Singleton variables?","answer":"<p>Proxy servers can be associated with Singleton variables in scenarios where a single proxy server instance is required to manage network communications. This promotes efficient resource utilization and centralized management.<\/p>"}]},"_links":{"self":[{"href":"https:\/\/oneproxy.pro\/jp\/wp-json\/wp\/v2\/wiki\/479015","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/oneproxy.pro\/jp\/wp-json\/wp\/v2\/wiki"}],"about":[{"href":"https:\/\/oneproxy.pro\/jp\/wp-json\/wp\/v2\/types\/wiki"}],"version-history":[{"count":0,"href":"https:\/\/oneproxy.pro\/jp\/wp-json\/wp\/v2\/wiki\/479015\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/oneproxy.pro\/jp\/wp-json\/wp\/v2\/media\/470508"}],"wp:attachment":[{"href":"https:\/\/oneproxy.pro\/jp\/wp-json\/wp\/v2\/media?parent=479015"}],"curies":[{"name":"\u3046\u30fc\u3093","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}