{"id":327,"date":"2014-10-21T19:03:33","date_gmt":"2014-10-21T10:03:33","guid":{"rendered":"http:\/\/kei0310.info\/?p=327"},"modified":"2014-10-21T19:03:33","modified_gmt":"2014-10-21T10:03:33","slug":"post-327","status":"publish","type":"post","link":"http:\/\/kei0310.info\/?p=327","title":{"rendered":"[Java] StringBuilder\u306e\u4f7f\u3044\u65b9\uff08String\u3092\u9023\u7d50\u3059\u308b\u30af\u30e9\u30b9\uff09"},"content":{"rendered":"

\u4eca\u56de\u306f\u3001\u53ef\u5909\u9577\u6587\u5b57\u5217\u30af\u30e9\u30b9\u306eStringBuilder\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n

\u56fa\u5b9a\u9577\u6587\u5b57\u5217\u30af\u30e9\u30b9\u306eString\u3068\u7570\u306a\u308b\u70b9\u306f\u4ee5\u4e0b\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n

\u25cf\u6587\u5b57\u5217\u3092\u9023\u7d50\u30fb\u524a\u9664\u3092\u30e1\u30e2\u30ea\u6d88\u8cbb\u3092\u6291\u3048\u3066\u5b9f\u884c\u53ef\u80fd<\/h1>\n

\uff1cString\u306e\u5834\u5408\uff1e<\/h2>\n

String\u3067\u6587\u5b57\u5217\u3092\u9023\u7d50\u3059\u308b\u3068\u3001\u4f59\u8a08\u306a\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u751f\u6210\u3092\u884c\u3063\u3066\u3057\u307e\u3044\u307e\u3059\u3002<\/p>\n

\u4f8b\uff09
\nStringA = \"abc\"
\nStringB = \"def\"
\nStringC = \"ghi\"
\nStringD = \"jkl\"<\/p>\n

StringA + StringB + StringC + StringD\u3092\u884c\u3046\u5834\u5408\u3001
\n\u524d\u306e\u9023\u7d50\u51e6\u7406\u304b\u3089\u9806\u756a\u306b\u5b9f\u884c\u3055\u308c\u308b\u305f\u3081\u3001
\n\u4ee5\u4e0b\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304c\u9023\u7d9a\u7684\u306b\u751f\u6210\u3055\u308c\u307e\u3059\u3002<\/p>\n

StringA + StringB = \"abcdef\" \u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8
\nStringA + StringB + StringC = \"abcdefghi\" \u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8
\nStringA + StringB + StringC + StringD = \"abcdefghijkl\" \u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8<\/p>\n

\u300cString\u30af\u30e9\u30b9\u304c\u81ea\u8eab\u3092\u5909\u66f4\u3067\u304d\u306a\u3044\u305f\u3081\u3001\u65b0\u3057\u3044String\u30af\u30e9\u30b9\u3092\u5e38\u306b\u751f\u6210\u3059\u308b\u300d
\n\u3053\u3068\u304c\u539f\u56e0\u3067\u767a\u751f\u3057\u3066\u3044\u308b\u4e8b\u8c61\u3067\u3059\u3002<\/p>\n

\u305d\u306e\u305f\u3081\u3001for\u3084while\u3067\u30eb\u30fc\u30d7\u3057\u305f\u51e6\u7406\u4e2d\u306bString\u306e\u6587\u5b57\u5217\u9023\u7d50\u3092\u66f8\u304f\u3068
\n\u4e57\u7b97\u3067\u4f7f\u7528\u30e1\u30e2\u30ea\u304c\u5897\u5927\u3057\u3066\u3044\u304d\u307e\u3059\u3002\u3088\u3063\u3066\u3001
\n\u300c\u30e1\u30e2\u30ea\u3092\u5927\u91cf\u306b\u6d88\u8cbb\uff0b\u30ac\u30d9\u30fc\u30b8\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u51e6\u7406\u3067\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u4f4e\u4e0b\u300d\u304c\u767a\u751f\u3057\u307e\u3059\u3002<\/p>\n

\uff1cStringBuilder\u306e\u5834\u5408\uff1e<\/h2>\n

\u5bfe\u3057\u3066\u3001\u4e0a\u8a18\u306e\u51e6\u7406\u3092StringBuilder\u3067\u884c\u3063\u3066\u307f\u307e\u3059\u3002<\/p>\n

StringA\uff5eD\u306f\u540c\u4e00\u3067\u3059\u3002<\/p>\n

\/\/ StringBuiilder\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u751f\u6210
\nStringBuilder builder = new StringBuilder();<\/p>\n

\/\/ StringA\uff5eD\u3092\u9023\u7d50
\nbuilder.append(StringA)
\nbuilder.append(StringB)
\nbuilder.append(StringC)
\nbuilder.append(StringD)<\/p>\n

builder\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306f\u7121\u6307\u5b9a\u3060\u306816\u30d0\u30a4\u30c8\u306e\u9818\u57df\u3092\u81ea\u8eab\u306b\u6301\u3063\u3066\u3044\u3066\u3001
\nappend\u3055\u308c\u305f\u6587\u5b57\u5217\u3092\u81ea\u8eab\u306e\u9818\u57df\u306b\u30b3\u30d4\u30fc\u3057\u307e\u3059\u3002
\n\u3067\u3059\u306e\u3067\u3001\u81ea\u8eab\u306e\u9818\u57df\u3092\u8d85\u3048\u306a\u3044\u9650\u308a\u306f\u8ffd\u52a0\u306e\u9818\u57df\u3092\u4f5c\u6210\u3057\u307e\u305b\u3093\u3002<\/p>\n

\u305f\u3060\u3057\u300116\u30d0\u30a4\u30c8\u3092\u8d85\u3048\u305f\u5834\u5408\u3001\u300c\uff08\u4ee5\u524d\u306e\u9818\u57df\uff0b\uff11\uff09\uff0a\uff12\u300d\u306e\u9818\u57df\u3092
\n\u65b0\u3057\u304f\u78ba\u4fdd\u3059\u308b\u305f\u3081\u3001\u983b\u7e41\u306b\u9818\u57df\u66f4\u65b0\u304c\u767a\u751f\u3059\u308b\u3068\u3001
\nString\u307e\u3067\u306f\u3044\u304d\u307e\u305b\u3093\u304c\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u4f4e\u4e0b\u304c\u8d77\u3053\u308a\u307e\u3059\u3002<\/p>\n

\u305d\u308c\u3092\u9632\u3050\u305f\u3081\u306b\u306f\u3001StringBuilder\u3092new\u3059\u308b\u3068\u304d\u306b\u30b5\u30a4\u30ba\u3092\u6307\u5b9a\u3057\u307e\u3059\u3002<\/p>\n

\/\/ 10000\u30d0\u30a4\u30c8\u3067StringBuilder\u3092\u4f5c\u6210
\nStringBuilder builder = new StringBuilder(10000);<\/p>\n

\u3042\u307e\u308a\u306b\u5927\u304d\u304f\u9818\u57df\u3092\u78ba\u4fdd\u3057\u3066\u3057\u307e\u3046\u3068\u3001\u305d\u308c\u306f\u305d\u308c\u3067\u7121\u99c4\u3067\u3059\u306e\u3067\u3001
\n\u51e6\u7406\u306b\u5fdc\u3058\u305f\u9069\u5207\u306a\u9818\u57df\u3092\u78ba\u4fdd\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n

\u6700\u5f8c\u306b\u7c21\u5358\u306a\u4f8b\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n

\n
\r\npublic class TestStringBuilder {\r\n\r\n\tpublic static void main(String[] args){\r\n\r\n\t\t\/\/ \u7121\u6307\u5b9a\u306e\u5834\u5408\u300116\u30d0\u30a4\u30c8\u3067\u521d\u671f\u5316\r\n\t\tStringBuilder builder = new StringBuilder();\r\n\r\n\t\t\/\/ 10\u6587\u5b57\u8ffd\u52a0\uff08\u5408\u8a0810\u30d0\u30a4\u30c8\uff09\r\n\t\tbuilder.append("1234567890");\r\n\t\t\/\/ 10\u6587\u5b57\u8ffd\u52a0\uff08\u5408\u8a0820\u30d0\u30a4\u30c8\uff09\uff1a\u3053\u3053\u3067\u3001(16+1)*2=34\u30d0\u30a4\u30c8\u306b\u62e1\u5f35\u3055\u308c\u308b\u3002\r\n\t\tbuilder.append("1234567890");\r\n\t\t\/\/ 10\u6587\u5b57\u8ffd\u52a0\uff08\u5408\u8a0830\u30d0\u30a4\u30c8\uff09\r\n\t\tbuilder.append("1234567890");\r\n\t\t\/\/ 10\u6587\u5b57\u8ffd\u52a0\uff08\u5408\u8a0840\u30d0\u30a4\u30c8\uff09\uff1a\u3053\u3053\u3067\u3001(34+1)*2=70\u30d0\u30a4\u30c8\u306b\u62e1\u5f35\u3055\u308c\u308b\u3002\r\n\t\tbuilder.append("1234567890");\r\n\r\n\t\t\/\/ \u6a19\u6e96\u51fa\u529b\u306b\u8868\u793a\uff08toString()\u3059\u308c\u3070String\u3067\u51fa\u529b\u53ef\u80fd\uff09\r\n\t\tSystem.out.println(builder.toString());\r\n\r\n\t}\r\n}\r\n<\/pre>\n<\/h6>\n","protected":false},"excerpt":{"rendered":"
\u4eca\u56de\u306f\u3001\u53ef\u5909\u9577\u6587\u5b57\u5217\u30af\u30e9\u30b9\u306eStringBuilder\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002 \u56fa\u5b9a\u9577\u6587\u5b57\u5217\u30af\u30e9\u30b9\u306eString\u3068\u7570\u306a\u308b\u70b9\u306f\u4ee5\u4e0b\u306b\u306a\u308a\u307e\u3059\u3002 \u25cf\u6587\u5b57\u5217\u3092\u9023\u7d50\u30fb\u524a\u9664\u3092\u30e1\u30e2\u30ea\u6d88\u8cbb\u3092\u6291\u3048\u3066\u5b9f\u884c\u53ef\u80fd \uff1cString\u306e\u5834\u5408\uff1e String\u3067 […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[4,28],"tags":[183,136,135,46,137],"_links":{"self":[{"href":"http:\/\/kei0310.info\/index.php?rest_route=\/wp\/v2\/posts\/327"}],"collection":[{"href":"http:\/\/kei0310.info\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"http:\/\/kei0310.info\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"http:\/\/kei0310.info\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"http:\/\/kei0310.info\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=327"}],"version-history":[{"count":1,"href":"http:\/\/kei0310.info\/index.php?rest_route=\/wp\/v2\/posts\/327\/revisions"}],"predecessor-version":[{"id":328,"href":"http:\/\/kei0310.info\/index.php?rest_route=\/wp\/v2\/posts\/327\/revisions\/328"}],"wp:attachment":[{"href":"http:\/\/kei0310.info\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=327"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"http:\/\/kei0310.info\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=327"},{"taxonomy":"post_tag","embeddable":true,"href":"http:\/\/kei0310.info\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=327"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}