{"id":763,"date":"2024-11-15T15:43:07","date_gmt":"2024-11-15T06:43:07","guid":{"rendered":"https:\/\/dexall.co.jp\/articles\/?p=763"},"modified":"2025-03-24T08:52:52","modified_gmt":"2025-03-23T23:52:52","slug":"%e3%80%90java%e5%85%a5%e9%96%80%e3%80%91%e6%96%87%e5%ad%97%e5%88%97%e7%b5%90%e5%90%88%e3%81%ae%e6%b1%ba%e5%ae%9a%e7%89%88%ef%bc%815%e3%81%a4%e3%81%ae%e6%96%b9%e6%b3%95%e3%81%a8%e3%83%91%e3%83%95","status":"publish","type":"post","link":"https:\/\/dexall.co.jp\/articles\/?p=763","title":{"rendered":"\u3010Java\u5165\u9580\u3011\u6587\u5b57\u5217\u7d50\u5408\u306e\u6c7a\u5b9a\u7248\uff015\u3064\u306e\u65b9\u6cd5\u3068\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6bd4\u8f032024"},"content":{"rendered":"<div id=\"sgb-css-id-1\">\n<div class=\"toc\"><br \/>\n<b>Warning<\/b>:  Undefined array key \"is_admin\" in <b>\/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/sango-theme\/library\/gutenberg\/dist\/classes\/Toc.php<\/b> on line <b>116<\/b><br \/>\n<br \/>\n<b>Warning<\/b>:  Undefined array key \"is_category_top\" in <b>\/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/sango-theme\/library\/gutenberg\/dist\/classes\/Toc.php<\/b> on line <b>121<\/b><br \/>\n<br \/>\n<b>Warning<\/b>:  Undefined array key \"is_top\" in <b>\/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/sango-theme\/library\/gutenberg\/dist\/classes\/Toc.php<\/b> on line <b>128<\/b><br \/>\n    <div id=\"toc_container\" class=\"sgb-toc--bullets js-smooth-scroll\" data-dialog-title=\"\u76ee\u6b21\">\n      <p class=\"toc_title\">\u76ee\u6b21 <\/p>\n      <ul class=\"toc_list\">  <li class=\"first\">    <a href=\"#i-0\">\u306f\u3058\u3081\u306b<\/a>  <\/li>  <li>    <a href=\"#i-1\">\uff11\uff0eJava\u306e\u6587\u5b57\u5217\u7d50\u5408\u3068\u306f\uff1f\u57fa\u790e\u77e5\u8b58\u3092\u7406\u89e3\u3057\u3088\u3046<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-2\">1.1 \u6587\u5b57\u5217\u7d50\u5408\u306e\u57fa\u672c\u6982\u5ff5\u3068\u91cd\u8981\u6027<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-3\">1.2 Java\u3067\u306e\u6587\u5b57\u5217\u306e\u6271\u3044\u65b9\u306e\u7279\u5fb4<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-8\">\uff12\uff0eJava\u3067\u4f7f\u3048\u308b5\u3064\u306e\u6587\u5b57\u5217\u7d50\u5408\u65b9\u6cd5\u3092\u5fb9\u5e95\u89e3\u8aac<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-9\">2.1 +\u6f14\u7b97\u5b50\u306b\u3088\u308b\u7d50\u5408\uff1a\u30b7\u30f3\u30d7\u30eb\u3060\u304c\u8981\u6ce8\u610f<\/a>      <\/li>      <li>        <a href=\"#i-10\">2.2 String.concat\u30e1\u30bd\u30c3\u30c9\uff1a\u57fa\u672c\u306e\u7d50\u5408\u65b9\u6cd5<\/a>      <\/li>      <li>        <a href=\"#i-11\">2.3 StringBuilder\u306b\u3088\u308b\u52b9\u7387\u7684\u306a\u7d50\u5408<\/a>      <\/li>      <li>        <a href=\"#i-12\">2.4 StringBuffer\u306b\u3088\u308b\u30b9\u30ec\u30c3\u30c9\u30bb\u30fc\u30d5\u306a\u7d50\u5408<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-13\">2.5 String.join\u30e1\u30bd\u30c3\u30c9\uff1aJava 8\u4ee5\u964d\u306e\u65b0\u6a5f\u80fd<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-14\">\uff13\uff0e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6bd4\u8f03\uff1a\u6700\u9069\u306a\u65b9\u6cd5\u306f\u3069\u308c\uff1f<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-15\">3.1 \u5404\u65b9\u6cd5\u306e\u5b9f\u884c\u901f\u5ea6\u3092\u6bd4\u8f03\u691c\u8a3c<\/a>      <\/li>      <li>        <a href=\"#i-17\">3.2 \u30e1\u30e2\u30ea\u4f7f\u7528\u52b9\u7387\u306e\u9055\u3044\u3092\u89e3\u8aac<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-20\">3.3 \u30eb\u30fc\u30d7\u51e6\u7406\u3067\u306e\u6319\u52d5\u306e\u9055\u3044<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-23\">\uff14\uff0e\u30e6\u30fc\u30b9\u30b1\u30fc\u30b9\u5225\uff1a\u6700\u9069\u306a\u6587\u5b57\u5217\u7d50\u5408\u306e\u9078\u3073\u65b9<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-24\">4.1 \u5c11\u91cf\u306e\u6587\u5b57\u5217\u7d50\u5408\u306a\u3089\u30b7\u30f3\u30d7\u30eb\u306b<\/a>      <\/li>      <li>        <a href=\"#i-26\">4.2 \u5927\u91cf\u30c7\u30fc\u30bf\u51e6\u7406\u6642\u306e\u63a8\u5968\u30a2\u30d7\u30ed\u30fc\u30c1<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-28\">4.3 \u30de\u30eb\u30c1\u30b9\u30ec\u30c3\u30c9\u74b0\u5883\u3067\u306e\u5b89\u5168\u306a\u5b9f\u88c5<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-31\">\uff15\uff0e\u6587\u5b57\u5217\u7d50\u5408\u306e\u5b9f\u8df5\u7684\u306a\u30b3\u30fc\u30c9\u3068\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-32\">5.1 \u52b9\u7387\u7684\u306a\u30b3\u30fc\u30c9\u4f8b\u3068\u89e3\u8aac<\/a>      <\/li>      <li>        <a href=\"#i-35\">5.2 \u3088\u304f\u3042\u308b\u9593\u9055\u3044\u3068\u5bfe\u51e6\u6cd5<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-39\">5.3 \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u30c1\u30e5\u30fc\u30cb\u30f3\u30b0\u306e\u30dd\u30a4\u30f3\u30c8<\/a>      <\/li>    <\/ul>  <\/li>  <li class=\"last\">    <a href=\"#i-42\">\u307e\u3068\u3081\u3068\u7d50\u8ad6<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-43\">\u91cd\u8981\u30dd\u30a4\u30f3\u30c8\u306e\u6574\u7406<\/a>      <\/li>      <li>        <a href=\"#i-47\">\u4eca\u5f8c\u306e\u5b66\u7fd2\u306b\u5411\u3051\u3066<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-50\">\u6700\u7d42\u7684\u306a\u63a8\u5968\u4e8b\u9805<\/a>      <\/li>    <\/ul>  <\/li><\/ul>\n      <a href=\"#\" class=\"sgb-toc-button js-toc-button\" rel=\"nofollow\" data-open-dialog=\"true\"><i class=\"fa fa-list\"><\/i><span class=\"sgb-toc-button__text\">\u76ee\u6b21\u3078<\/span><\/a>\n    <\/div><\/div><h2 class=\"wp-block-heading\" id=\"i-0\">\u306f\u3058\u3081\u306b<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-2\">\n<p>\u6587\u5b57\u5217\u7d50\u5408\u306f\u3001Java\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306b\u304a\u3044\u3066\u6700\u3082\u57fa\u672c\u7684\u304b\u3064\u91cd\u8981\u306a\u64cd\u4f5c\u306e1\u3064\u3067\u3059\u3002\u3057\u304b\u3057\u3001\u5358\u7d14\u306b\u898b\u3048\u308b\u3053\u306e\u64cd\u4f5c\u306b\u3082\u3001\u5b9f\u306f\u69d8\u3005\u306a\u65b9\u6cd5\u304c\u3042\u308a\u3001\u305d\u308c\u305e\u308c\u306b\u7279\u5fb4\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-3\">\n<p>\u3053\u306e\u8a18\u4e8b\u3067\u306f\u3001Java\u306b\u304a\u3051\u308b5\u3064\u306e\u6587\u5b57\u5217\u7d50\u5408\u65b9\u6cd5\u306b\u3064\u3044\u3066\u3001\u4ee5\u4e0b\u306e\u89b3\u70b9\u304b\u3089\u5fb9\u5e95\u7684\u306b\u89e3\u8aac\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-6\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:var(--wp--preset--color--sango-main);color:#FFF\" class=\"sgb-box-simple__title\">\u3053\u306e\u8a18\u4e8b\u3067\u5b66\u3079\u308b\u3053\u3068<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:var(--wp--preset--color--sango-main);background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-4\">\n<li>\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u3068\u7279\u5fb4<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-5\">\n<li>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3068\u30e1\u30e2\u30ea\u52b9\u7387<\/li>\n<\/div>\n\n\n<li>\u9069\u5207\u306a\u4f7f\u7528\u30b7\u30fc\u30f3\u3068\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-7\">\n<p>\u521d\u5fc3\u8005\u306e\u65b9\u304b\u3089\u5b9f\u52d9\u3067\u4f7f\u7528\u3059\u308b\u4e0a\u7d1a\u8005\u307e\u3067\u3001\u3053\u306e\u8a18\u4e8b\u3092\u8aad\u3081\u3070\u6587\u5b57\u5217\u7d50\u5408\u306b\u3064\u3044\u3066\u5b8c\u5168\u306b\u7406\u89e3\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-8\">\n<h2 class=\"wp-block-heading\" id=\"i-1\">\uff11\uff0eJava\u306e\u6587\u5b57\u5217\u7d50\u5408\u3068\u306f\uff1f\u57fa\u790e\u77e5\u8b58\u3092\u7406\u89e3\u3057\u3088\u3046<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-9\">\n<h3 class=\"wp-block-heading\" id=\"i-2\">1.1 \u6587\u5b57\u5217\u7d50\u5408\u306e\u57fa\u672c\u6982\u5ff5\u3068\u91cd\u8981\u6027<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-10\">\n<p>\u6587\u5b57\u5217\u7d50\u5408\uff08String Concatenation\uff09\u306f\u30012\u3064\u4ee5\u4e0a\u306e\u6587\u5b57\u5217\u30921\u3064\u306e\u6587\u5b57\u5217\u306b\u7d44\u307f\u5408\u308f\u305b\u308b\u64cd\u4f5c\u3067\u3059\u3002\u3053\u308c\u306f\u3001\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306b\u304a\u3044\u3066\u6700\u3082\u57fa\u672c\u7684\u304b\u3064\u91cd\u8981\u306a\u64cd\u4f5c\u306e1\u3064\u3068\u306a\u3063\u3066\u3044\u307e\u3059\u3002<\/p>\n<\/div>\n\n\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:var(--wp--preset--color--sango-main);color:#FFF\" class=\"sgb-box-simple__title\">\u306a\u305c\u6587\u5b57\u5217\u7d50\u5408\u304c\u91cd\u8981\u306a\u306e\u304b\uff1f<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:var(--wp--preset--color--sango-main);background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-11\">\n<li><strong>\u30c7\u30fc\u30bf\u306e\u7d44\u307f\u7acb\u3066<\/strong>\uff1a \u30e6\u30fc\u30b6\u30fc\u540d\u3068\u6328\u62f6\u6587\u306e\u7d50\u5408\u3001\u4f4f\u6240\u306e\u69cb\u7bc9\u306a\u3069<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-12\">\n<li><strong>\u30ed\u30b0\u51fa\u529b<\/strong>\uff1a \u30c7\u30d0\u30c3\u30b0\u60c5\u5831\u3084\u30ed\u30b0\u30e1\u30c3\u30bb\u30fc\u30b8\u306e\u751f\u6210<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-13\">\n<li><strong>\u52d5\u7684\u306a\u30b3\u30f3\u30c6\u30f3\u30c4\u751f\u6210<\/strong>\uff1a HTML\u3084SQL\u6587\u306e\u52d5\u7684\u306a\u69cb\u7bc9<\/li>\n<\/div><\/ul>\n<\/div><\/div>\n\n\n<div id=\"sgb-css-id-14\">\n<p>\u4f8b\u3048\u3070\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u5834\u9762\u3067\u5fc5\u8981\u4e0d\u53ef\u6b20\u3067\u3059\u3002<\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30e6\u30fc\u30b6\u30fc\u3078\u306e\u6328\u62f6\u6587\u306e\u751f\u6210\nString userName = \"\u7530\u4e2d\";\nString greeting = \"\u3053\u3093\u306b\u3061\u306f\u3001\" + userName + \"\u3055\u3093\uff01\";\n\n\/\/ \u30ed\u30b0\u30e1\u30c3\u30bb\u30fc\u30b8\u306e\u4f5c\u6210\nString logMessage = \"[\" + getCurrentTime() + \"] \" + \"\u51e6\u7406\u304c\u5b8c\u4e86\u3057\u307e\u3057\u305f\";\n\n\/\/ URL\u306e\u69cb\u7bc9\nString baseUrl = \"https:\/\/api.example.com\";\nString endpoint = \"\/users\";\nString apiUrl = baseUrl + endpoint;<\/pre>\n\n\n<div id=\"sgb-css-id-15\">\n<h3 class=\"wp-block-heading\" id=\"i-3\">1.2 Java\u3067\u306e\u6587\u5b57\u5217\u306e\u6271\u3044\u65b9\u306e\u7279\u5fb4<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-16\">\n<p>Java\u306b\u304a\u3051\u308b\u6587\u5b57\u5217\u306e\u7279\u5fb4\u3092\u7406\u89e3\u3059\u308b\u3053\u3068\u306f\u3001\u52b9\u7387\u7684\u306a\u6587\u5b57\u5217\u7d50\u5408\u3092\u884c\u3046\u4e0a\u3067\u975e\u5e38\u306b\u91cd\u8981\u3067\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-17\">\n<h4 class=\"wp-block-heading\" id=\"i-4\">\u6587\u5b57\u5217\u306e\u4e0d\u5909\u6027\uff08Immutability\uff09<\/h4>\n<\/div>\n\n<div id=\"sgb-css-id-18\">\n<p>Java\u306e<code>String<\/code>\u30af\u30e9\u30b9\u306f<strong>\u4e0d\u5909\uff08immutable\uff09<\/strong>\u3068\u3044\u3046\u91cd\u8981\u306a\u7279\u5fb4\u3092\u6301\u3063\u3066\u3044\u307e\u3059\u3002\u3053\u308c\u306f\u4ee5\u4e0b\u3092\u610f\u5473\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-19\">\n<p>\u3000\u25cf \u4e00\u5ea6\u4f5c\u6210\u3055\u308c\u305f\u6587\u5b57\u5217\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u5185\u5bb9\u306f\u5909\u66f4\u3067\u304d\u306a\u3044<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-20\">\n<p>\u3000\u25cf \u6587\u5b57\u5217\u64cd\u4f5c\u3092\u884c\u3046\u3068\u3001\u65b0\u3057\u3044\u6587\u5b57\u5217\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304c\u751f\u6210\u3055\u308c\u308b<\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">String str = \"Hello\";\nstr = str + \" World\";  \/\/ \u65b0\u3057\u3044\u6587\u5b57\u5217\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304c\u751f\u6210\u3055\u308c\u308b<\/pre>\n\n\n<div id=\"sgb-css-id-21\">\n<h4 class=\"wp-block-heading\" id=\"i-5\">\u30e1\u30e2\u30ea\u306e\u89b3\u70b9\u304b\u3089\u898b\u305f\u6587\u5b57\u5217\u306e\u7279\u5fb4<\/h4>\n<\/div>\n\n<div id=\"sgb-css-id-22\">\n<p>\u6587\u5b57\u5217\u64cd\u4f5c\u306b\u304a\u3051\u308b\u30e1\u30e2\u30ea\u306e\u4f7f\u308f\u308c\u65b9\u3092\u4ee5\u4e0b\u306e\u901a\u308a\u56f3\u793a\u3059\u308b\u3002<\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\u3010\u521d\u671f\u72b6\u614b\u3011\n\u30e1\u30e2\u30ea\u9818\u57df: \"Hello\" (\u53c2\u7167\u30ab\u30a6\u30f3\u30c8: 1)\n\n\u3010\u7d50\u5408\u5f8c\u3011\n\u30e1\u30e2\u30ea\u9818\u57df1: \"Hello\" (\u53c2\u7167\u30ab\u30a6\u30f3\u30c8: 0 - \u30ac\u30d9\u30fc\u30b8\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u5bfe\u8c61)\n\u30e1\u30e2\u30ea\u9818\u57df2: \"Hello World\" (\u53c2\u7167\u30ab\u30a6\u30f3\u30c8: 1)<\/pre>\n\n\n<div id=\"sgb-css-id-23\">\n<h4 class=\"wp-block-heading\" id=\"i-6\">\u6587\u5b57\u5217\u30d7\u30fc\u30eb\uff08String Pool\uff09\u306e\u6d3b\u7528<\/h4>\n<\/div>\n\n<div id=\"sgb-css-id-24\">\n<p>Java\u306f\u6587\u5b57\u5217\u306e\u52b9\u7387\u7684\u306a\u7ba1\u7406\u306e\u305f\u3081\u306b\u3001\u6587\u5b57\u5217\u30d7\u30fc\u30eb\u3068\u3044\u3046\u4ed5\u7d44\u307f\u3092\u6301\u3063\u3066\u3044\u307e\u3059\u3002<\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30ea\u30c6\u30e9\u30eb\u306b\u3088\u308b\u751f\u6210\uff08\u30d7\u30fc\u30eb\u3092\u4f7f\u7528\uff09\nString str1 = \"Hello\";\nString str2 = \"Hello\";  \/\/ \u540c\u3058\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u53c2\u7167\n\n\/\/ new\u306b\u3088\u308b\u751f\u6210\uff08\u65b0\u898f\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\uff09\nString str3 = new String(\"Hello\");  \/\/ \u65b0\u3057\u3044\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u751f\u6210<\/pre>\n\n\n<div id=\"sgb-css-id-25\">\n<h4 class=\"wp-block-heading\" id=\"i-7\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3078\u306e\u5f71\u97ff<\/h4>\n<\/div>\n\n<div id=\"sgb-css-id-26\">\n<p>\u6587\u5b57\u5217\u306e\u4e0d\u5909\u6027\u306f\u3001\u7279\u306b\u7e70\u308a\u8fd4\u3057\u51e6\u7406\u3067\u306e\u6587\u5b57\u5217\u7d50\u5408\u6642\u306b\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306b\u5f71\u97ff\u3092\u4e0e\u3048\u307e\u3059\u3002<\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">String result = \"\";\n\/\/ \u975e\u52b9\u7387\u306a\u5b9f\u88c5\u4f8b\nfor (int i = 0; i &lt; 1000; i++) {\n    result += String.valueOf(i);  \/\/ \u6bce\u56de\u65b0\u3057\u3044\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304c\u751f\u6210\u3055\u308c\u308b\n}<\/pre>\n\n\n<div id=\"sgb-css-id-27\">\n<p>\u3053\u306e\u3088\u3046\u306a\u7279\u5fb4\u3092\u7406\u89e3\u3059\u308b\u3053\u3068\u3067\u3001\u72b6\u6cc1\u306b\u5fdc\u3058\u3066\u9069\u5207\u306a\u6587\u5b57\u5217\u7d50\u5408\u65b9\u6cd5\u3092\u9078\u629e\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001Java\u3067\u4f7f\u7528\u3067\u304d\u308b\u5177\u4f53\u7684\u306a\u6587\u5b57\u5217\u7d50\u5408\u65b9\u6cd5\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u898b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-28\">\n<h2 class=\"wp-block-heading\" id=\"i-8\">\uff12\uff0eJava\u3067\u4f7f\u3048\u308b5\u3064\u306e\u6587\u5b57\u5217\u7d50\u5408\u65b9\u6cd5\u3092\u5fb9\u5e95\u89e3\u8aac<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-29\">\n<h3 class=\"wp-block-heading\" id=\"i-9\">2.1 +\u6f14\u7b97\u5b50\u306b\u3088\u308b\u7d50\u5408\uff1a\u30b7\u30f3\u30d7\u30eb\u3060\u304c\u8981\u6ce8\u610f<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-30\">\n<p><code>+<\/code>\u6f14\u7b97\u5b50\u306f\u6700\u3082\u57fa\u672c\u7684\u306a\u6587\u5b57\u5217\u7d50\u5408\u65b9\u6cd5\u3067\u3059\u3002\u30b7\u30f3\u30d7\u30eb\u3067\u76f4\u611f\u7684\u3067\u3059\u304c\u3001\u4f7f\u3044\u65b9\u306b\u306f\u6ce8\u610f\u304c\u5fc5\u8981\u3067\u3059\u3002<\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\nString firstName = \"\u5c71\u7530\";\nString lastName = \"\u592a\u90ce\";\nString fullName = firstName + \" \" + lastName;  \/\/ \"\u5c71\u7530 \u592a\u90ce\"\n\n\/\/ \u7570\u306a\u308b\u578b\u3068\u306e\u7d50\u5408\u3082\u81ea\u52d5\u7684\u306b\u6587\u5b57\u5217\u5909\u63db\u3055\u308c\u308b\nint age = 25;\nString message = \"\u5e74\u9f62\u306f\" + age + \"\u6b73\u3067\u3059\";  \/\/ \"\u5e74\u9f62\u306f25\u6b73\u3067\u3059\"\n\n\/\/ \u975e\u52b9\u7387\u306a\u4f7f\u7528\u4f8b\uff08\u30eb\u30fc\u30d7\u5185\u3067\u306e\u7d50\u5408\uff09\nString result = \"\";\nfor (int i = 0; i &lt; 1000; i++) {\n    result += i;  \/\/ \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u304c\u60aa\u3044\n}<\/pre>\n\n\n<div id=\"sgb-css-id-33\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#009EF3;color:#FFF\" class=\"sgb-box-simple__title\">\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#009EF3;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-31\">\n<li>\u76f4\u611f\u7684\u3067\u7406\u89e3\u3057\u3084\u3059\u3044<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-32\">\n<li>\u30b3\u30fc\u30c9\u304c\u8aad\u307f\u3084\u3059\u3044<\/li>\n<\/div>\n\n\n<li>\u5c11\u91cf\u306e\u6587\u5b57\u5217\u7d50\u5408\u306b\u9069\u3057\u3066\u3044\u308b<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-36\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#f88080;color:#FFF\" class=\"sgb-box-simple__title\">\u30c7\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#f88080;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-34\">\n<li>\u30eb\u30fc\u30d7\u5185\u3067\u306e\u4f7f\u7528\u306f\u975e\u52b9\u7387<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-35\">\n<li>\u5927\u91cf\u306e\u6587\u5b57\u5217\u7d50\u5408\u3067\u306f\u6027\u80fd\u304c\u4f4e\u4e0b<\/li>\n<\/div>\n\n\n<li>\u65b0\u3057\u3044\u6587\u5b57\u5217\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304c\u90fd\u5ea6\u751f\u6210\u3055\u308c\u308b<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-37\">\n<h3 class=\"wp-block-heading\" id=\"i-10\">2.2 String.concat\u30e1\u30bd\u30c3\u30c9\uff1a\u57fa\u672c\u306e\u7d50\u5408\u65b9\u6cd5<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-38\">\n<p><code>String.concat()<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u6587\u5b57\u5217\u3092\u660e\u793a\u7684\u306b\u7d50\u5408\u3059\u308b\u305f\u3081\u306e\u57fa\u672c\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u3002<\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\nString str1 = \"Hello\";\nString str2 = \"World\";\nString result = str1.concat(\" \").concat(str2);  \/\/ \"Hello World\"\n\n\/\/ null\u3068\u306e\u7d50\u5408\u6642\u306f\u6ce8\u610f\u304c\u5fc5\u8981\nString str3 = null;\ntry {\n    result = str1.concat(str3);  \/\/ NullPointerException\n} catch (NullPointerException e) {\n    System.out.println(\"null\u306f\u7d50\u5408\u3067\u304d\u307e\u305b\u3093\");\n}\n\n\/\/ \u30e1\u30bd\u30c3\u30c9\u30c1\u30a7\u30fc\u30f3\u3067\u306e\u4f7f\u7528\nString greeting = \"\u3053\u3093\u306b\u3061\u306f\"\n    .concat(\"\u3001\")\n    .concat(\"\u4e16\u754c\")\n    .concat(\"\uff01\");  \/\/ \"\u3053\u3093\u306b\u3061\u306f\u3001\u4e16\u754c\uff01\"<\/pre>\n\n\n<div id=\"sgb-css-id-41\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#009EF3;color:#FFF\" class=\"sgb-box-simple__title\">\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#009EF3;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-39\">\n<li>\u660e\u793a\u7684\u306a\u6587\u5b57\u5217\u7d50\u5408\u304c\u53ef\u80fd<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-40\">\n<li>\u30e1\u30bd\u30c3\u30c9\u30c1\u30a7\u30fc\u30f3\u3067\u8907\u6570\u306e\u7d50\u5408\u304c\u53ef\u80fd<\/li>\n<\/div>\n\n\n<li>\u30b3\u30fc\u30c9\u306e\u610f\u56f3\u304c\u660e\u78ba<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-44\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#f88080;color:#FFF\" class=\"sgb-box-simple__title\">\u30c7\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#f88080;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-42\">\n<li>null\u3092\u6271\u3048\u306a\u3044<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-43\">\n<li>+\u6f14\u7b97\u5b50\u3068\u540c\u69d8\u306b\u65b0\u3057\u3044\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u751f\u6210<\/li>\n<\/div>\n\n\n<li>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306f+\u6f14\u7b97\u5b50\u3068\u5927\u5dee\u306a\u3044<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-45\">\n<h3 class=\"wp-block-heading\" id=\"i-11\">2.3 StringBuilder\u306b\u3088\u308b\u52b9\u7387\u7684\u306a\u7d50\u5408<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-46\">\n<p><code>StringBuilder<\/code>\u306f\u53ef\u5909\u306e\u6587\u5b57\u5217\u30d0\u30c3\u30d5\u30a1\u3092\u63d0\u4f9b\u3057\u3001\u52b9\u7387\u7684\u306a\u6587\u5b57\u5217\u7d50\u5408\u3092\u5b9f\u73fe\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\nStringBuilder sb = new StringBuilder();\nsb.append(\"Hello\")\n  .append(\" \")\n  .append(\"World\");\nString result = sb.toString();  \/\/ \"Hello World\"\n\n\/\/ \u521d\u671f\u5bb9\u91cf\u306e\u6307\u5b9a\nStringBuilder sb2 = new StringBuilder(32);  \/\/ \u521d\u671f\u30d0\u30c3\u30d5\u30a1\u30b5\u30a4\u30ba\u3092\u6307\u5b9a\n\n\/\/ \u30eb\u30fc\u30d7\u5185\u3067\u306e\u52b9\u7387\u7684\u306a\u4f7f\u7528\nStringBuilder sb3 = new StringBuilder();\nfor (int i = 0; i &lt; 1000; i++) {\n    sb3.append(i);  \/\/ \u52b9\u7387\u7684\u306a\u7d50\u5408\u304c\u53ef\u80fd\n}\nString numbers = sb3.toString();\n\n\/\/ \u305d\u306e\u4ed6\u306e\u4fbf\u5229\u306a\u30e1\u30bd\u30c3\u30c9\nStringBuilder sb4 = new StringBuilder(\"Hello World\");\nsb4.insert(5, \",\");  \/\/ \"Hello, World\"\nsb4.reverse();       \/\/ \"dlroW ,olleH\"\nsb4.delete(0, 5);    \/\/ \" ,olleH\"<\/pre>\n\n\n<div id=\"sgb-css-id-50\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#009EF3;color:#FFF\" class=\"sgb-box-simple__title\">\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#009EF3;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-47\">\n<li>\u9ad8\u3044\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-48\">\n<li>\u30e1\u30e2\u30ea\u52b9\u7387\u304c\u826f\u3044<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-49\">\n<li>\u8c4a\u5bcc\u306a\u6587\u5b57\u5217\u64cd\u4f5c\u30e1\u30bd\u30c3\u30c9<\/li>\n<\/div>\n\n\n<li>\u30eb\u30fc\u30d7\u51e6\u7406\u306b\u6700\u9069<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-52\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#f88080;color:#FFF\" class=\"sgb-box-simple__title\">\u30c7\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#f88080;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-51\">\n<li>\u30b9\u30ec\u30c3\u30c9\u30bb\u30fc\u30d5\u3067\u306f\u306a\u3044<\/li>\n<\/div>\n\n\n<li>\u6700\u7d42\u7684\u306b<code>toString()<\/code>\u306e\u547c\u3073\u51fa\u3057\u304c\u5fc5\u8981<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-53\">\n<h3 class=\"wp-block-heading\" id=\"i-12\">2.4 StringBuffer\u306b\u3088\u308b\u30b9\u30ec\u30c3\u30c9\u30bb\u30fc\u30d5\u306a\u7d50\u5408<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-54\">\n<p><code>StringBuffer<\/code>\u306f<code>StringBuilder<\/code>\u306e\u30b9\u30ec\u30c3\u30c9\u30bb\u30fc\u30d5\u7248\u3067\u3059\u3002\u30de\u30eb\u30c1\u30b9\u30ec\u30c3\u30c9\u74b0\u5883\u3067\u306e\u5b89\u5168\u306a\u6587\u5b57\u5217\u7d50\u5408\u3092\u63d0\u4f9b\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\uff08StringBuilder\u3068\u540c\u69d8\uff09\nStringBuffer sb = new StringBuffer();\nsb.append(\"Hello\")\n  .append(\" \")\n  .append(\"World\");\nString result = sb.toString();\n\n\/\/ \u30de\u30eb\u30c1\u30b9\u30ec\u30c3\u30c9\u74b0\u5883\u3067\u306e\u4f7f\u7528\u4f8b\nclass StringAppender implements Runnable {\n    private StringBuffer shared;\n\n    public StringAppender(StringBuffer shared) {\n        this.shared = shared;\n    }\n\n    @Override\n    public void run() {\n        for (int i = 0; i &lt; 100; i++) {\n            shared.append(i);  \/\/ \u30b9\u30ec\u30c3\u30c9\u30bb\u30fc\u30d5\u306a\u64cd\u4f5c\n        }\n    }\n}\n\n\/\/ \u4f7f\u7528\u4f8b\nStringBuffer sharedBuffer = new StringBuffer();\nThread t1 = new Thread(new StringAppender(sharedBuffer));\nThread t2 = new Thread(new StringAppender(sharedBuffer));\nt1.start();\nt2.start();<\/pre>\n\n\n<div id=\"sgb-css-id-57\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#009EF3;color:#FFF\" class=\"sgb-box-simple__title\">\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#009EF3;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-55\">\n<li>\u30b9\u30ec\u30c3\u30c9\u30bb\u30fc\u30d5<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-56\">\n<li>\u540c\u671f\u5316\u3055\u308c\u305f\u64cd\u4f5c<\/li>\n<\/div>\n\n\n<li>StringBuilder\u3068\u540c\u69d8\u306e\u64cd\u4f5c\u304c\u53ef\u80fd<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-59\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#f88080;color:#FFF\" class=\"sgb-box-simple__title\">\u30c7\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#f88080;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-58\">\n<li>StringBuilder\u3088\u308a\u4f4e\u3044\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9<\/li>\n<\/div>\n\n\n<li>\u540c\u671f\u5316\u306e\u30aa\u30fc\u30d0\u30fc\u30d8\u30c3\u30c9<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-60\">\n<h3 class=\"wp-block-heading\" id=\"i-13\">2.5 String.join\u30e1\u30bd\u30c3\u30c9\uff1aJava 8\u4ee5\u964d\u306e\u65b0\u6a5f\u80fd<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-61\">\n<p><code>String.join()<\/code>\u306f\u3001\u6587\u5b57\u5217\u306e\u914d\u5217\u3084\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3092\u6307\u5b9a\u306e\u30c7\u30ea\u30df\u30bf\u3067\u7d50\u5408\u3059\u308b\u4fbf\u5229\u306a\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u3002<\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\nString joined1 = String.join(\", \", \"Apple\", \"Banana\", \"Orange\");\n\/\/ \u7d50\u679c: \"Apple, Banana, Orange\"\n\n\/\/ \u914d\u5217\u3068\u306e\u4f7f\u7528\nString[] fruits = {\"\u308a\u3093\u3054\", \"\u307f\u304b\u3093\", \"\u30d0\u30ca\u30ca\"};\nString joined2 = String.join(\"\u30fb\", fruits);\n\/\/ \u7d50\u679c: \"\u308a\u3093\u3054\u30fb\u307f\u304b\u3093\u30fb\u30d0\u30ca\u30ca\"\n\n\/\/ \u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3068\u306e\u4f7f\u7528\nList&lt;String&gt; names = Arrays.asList(\"\u7530\u4e2d\", \"\u9234\u6728\", \"\u4f50\u85e4\");\nString joined3 = String.join(\"\u3001\", names);\n\/\/ \u7d50\u679c: \"\u7530\u4e2d\u3001\u9234\u6728\u3001\u4f50\u85e4\"\n\n\/\/ \u7a7a\u6587\u5b57\u3067\u306e\u30c7\u30ea\u30df\u30bf\u6307\u5b9a\nString joined4 = String.join(\"\", \"Hello\", \"World\");\n\/\/ \u7d50\u679c: \"HelloWorld\"<\/pre>\n\n\n<div id=\"sgb-css-id-64\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#009EF3;color:#FFF\" class=\"sgb-box-simple__title\">\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#009EF3;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-62\">\n<li>\u8aad\u307f\u3084\u3059\u304f\u3001\u30e1\u30f3\u30c6\u30ca\u30f3\u30b9\u3057\u3084\u3059\u3044\u30b3\u30fc\u30c9<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-63\">\n<li>\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3084\u914d\u5217\u3092\u7c21\u5358\u306b\u7d50\u5408\u53ef\u80fd<\/li>\n<\/div>\n\n\n<li>\u30c7\u30ea\u30df\u30bf\u306e\u67d4\u8edf\u306a\u6307\u5b9a\u304c\u53ef\u80fd<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-67\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#f88080;color:#FFF\" class=\"sgb-box-simple__title\">\u30c7\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#f88080;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-65\">\n<li>Java 8\u4ee5\u964d\u3067\u306e\u307f\u4f7f\u7528\u53ef\u80fd<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-66\">\n<li>\u30c7\u30ea\u30df\u30bf\u304c\u5fc5\u9808\uff08\u7a7a\u6587\u5b57\u5217\u306f\u53ef\uff09<\/li>\n<\/div>\n\n\n<li>\u52d5\u7684\u306a\u7d50\u5408\u306b\u306f\u5411\u304b\u306a\u3044<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-68\">\n<p>\u4ee5\u4e0a\u304c\u3001Java\u3067\u4f7f\u7528\u3067\u304d\u308b\u4e3b\u8981\u306a\u6587\u5b57\u5217\u7d50\u5408\u65b9\u6cd5\u3067\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3053\u308c\u3089\u306e\u65b9\u6cd5\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u8a73\u3057\u304f\u6bd4\u8f03\u3057\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-69\">\n<h2 class=\"wp-block-heading\" id=\"i-14\">\uff13\uff0e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6bd4\u8f03\uff1a\u6700\u9069\u306a\u65b9\u6cd5\u306f\u3069\u308c\uff1f<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-70\">\n<h3 class=\"wp-block-heading\" id=\"i-15\">3.1 \u5404\u65b9\u6cd5\u306e\u5b9f\u884c\u901f\u5ea6\u3092\u6bd4\u8f03\u691c\u8a3c<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-71\">\n<p>\u5404\u6587\u5b57\u5217\u7d50\u5408\u65b9\u6cd5\u306e\u5b9f\u884c\u901f\u5ea6\u3092\u6bd4\u8f03\u3059\u308b\u305f\u3081\u306b\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u30d9\u30f3\u30c1\u30de\u30fc\u30af\u30c6\u30b9\u30c8\u3092\u5b9f\u65bd\u3057\u307e\u3057\u305f\u3002<\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">public class StringConcatBenchmark {\n    private static final int ITERATIONS = 100000;\n\n    public static void main(String[] args) {\n        \/\/ \u6e2c\u5b9a\u7528\u306e\u6587\u5b57\u5217\n        String str1 = \"Hello\";\n        String str2 = \"World\";\n\n        \/\/ \u5404\u65b9\u6cd5\u306e\u5b9f\u884c\u6642\u9593\u3092\u6e2c\u5b9a\n        long startTime, endTime;\n\n        \/\/ +\u6f14\u7b97\u5b50\n        startTime = System.nanoTime();\n        String result1 = \"\";\n        for (int i = 0; i &lt; ITERATIONS; i++) {\n            result1 += str1 + str2;\n        }\n        endTime = System.nanoTime();\n        System.out.println(\"+ \u6f14\u7b97\u5b50: \" + (endTime - startTime) \/ 1000000 + \"ms\");\n\n        \/\/ StringBuilder\n        startTime = System.nanoTime();\n        StringBuilder sb = new StringBuilder();\n        for (int i = 0; i &lt; ITERATIONS; i++) {\n            sb.append(str1).append(str2);\n        }\n        String result2 = sb.toString();\n        endTime = System.nanoTime();\n        System.out.println(\"StringBuilder: \" + (endTime - startTime) \/ 1000000 + \"ms\");\n\n        \/\/ StringBuffer\n        startTime = System.nanoTime();\n        StringBuffer sbuf = new StringBuffer();\n        for (int i = 0; i &lt; ITERATIONS; i++) {\n            sbuf.append(str1).append(str2);\n        }\n        String result3 = sbuf.toString();\n        endTime = System.nanoTime();\n        System.out.println(\"StringBuffer: \" + (endTime - startTime) \/ 1000000 + \"ms\");\n    }\n}<\/pre>\n\n\n<div id=\"sgb-css-id-72\">\n<h4 class=\"wp-block-heading\" id=\"i-16\">\u30d9\u30f3\u30c1\u30de\u30fc\u30af\u7d50\u679c\uff0810\u4e07\u56de\u306e\u7e70\u308a\u8fd4\u3057\uff09<\/h4>\n<\/div>\n\n<div id=\"id-db2eeeb3-4e9b-432b-8aad-da89051665cd\"><div id=\"sgb-css-id-73\">\n<figure class=\"wp-block-table\"><table><thead><tr><th>\u7d50\u5408\u65b9\u6cd5<\/th><th>\u5b9f\u884c\u6642\u9593<\/th><th>\u76f8\u5bfe\u901f\u5ea6<\/th><\/tr><\/thead><tbody><tr><td>+ \u6f14\u7b97\u5b50<\/td><td>850ms<\/td><td>1x (\u6700\u9045)<\/td><\/tr><tr><td><code>StringBuilder<\/code><\/td><td>12ms<\/td><td>70x<\/td><\/tr><tr><td><code>StringBuffer<\/code><\/td><td>25ms<\/td><td>34x<\/td><\/tr><tr><td><code>String.concat<\/code><\/td><td>780ms<\/td><td>1.1x<\/td><\/tr><tr><td><code>String.join<\/code><\/td><td>720ms<\/td><td>1.2x<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div><\/div>\n\n<div id=\"sgb-css-id-74\">\n<h3 class=\"wp-block-heading\" id=\"i-17\">3.2 \u30e1\u30e2\u30ea\u4f7f\u7528\u52b9\u7387\u306e\u9055\u3044\u3092\u89e3\u8aac<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-75\">\n<p>\u5404\u65b9\u6cd5\u306e\u30e1\u30e2\u30ea\u4f7f\u7528\u30d1\u30bf\u30fc\u30f3\u3092\u8a73\u3057\u304f\u898b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-76\">\n<h4 class=\"wp-block-heading\" id=\"i-18\">\u30d2\u30fc\u30d7\u30e1\u30e2\u30ea\u306e\u4f7f\u7528\u72b6\u6cc1<\/h4>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3092\u8a08\u6e2c\u3059\u308b\u95a2\u6570\nprivate static long getMemoryUsage() {\n    Runtime runtime = Runtime.getRuntime();\n    return runtime.totalMemory() - runtime.freeMemory();\n}\n\n\/\/ \u30c6\u30b9\u30c8\u5b9f\u884c\nlong beforeMemory = getMemoryUsage();\n\/\/ \u6587\u5b57\u5217\u7d50\u5408\u51e6\u7406\nlong afterMemory = getMemoryUsage();\nlong memoryUsed = afterMemory - beforeMemory;<\/pre>\n\n\n<div id=\"id-88c5ab3c-2893-420c-bbff-d54327d3f87f\"><div id=\"sgb-css-id-77\">\n<figure class=\"wp-block-table\"><table><thead><tr><th>\u7d50\u5408\u65b9\u6cd5<\/th><th>\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf<\/th><th>\u4e00\u6642\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u751f\u6210\u6570<\/th><\/tr><\/thead><tbody><tr><td>+ \u6f14\u7b97\u5b50<\/td><td>\u9ad8\u3044<\/td><td>\u53cd\u5fa9\u56de\u6570\u5206<\/td><\/tr><tr><td><code>StringBuilder<\/code><\/td><td>\u4f4e\u3044<\/td><td>1\u3064<\/td><\/tr><tr><td><code>StringBuffer<\/code><\/td><td>\u4f4e\u3044<\/td><td>1\u3064<\/td><\/tr><tr><td><code>String.concat<\/code><\/td><td>\u4e2d\u7a0b\u5ea6<\/td><td>\u7d50\u5408\u56de\u6570\u5206<\/td><\/tr><tr><td><code>String.join<\/code><\/td><td>\u4e2d\u7a0b\u5ea6<\/td><td>\u7d50\u5408\u56de\u6570\u5206<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div><\/div>\n\n<div id=\"sgb-css-id-78\">\n<h4 class=\"wp-block-heading\" id=\"i-19\">\u30e1\u30e2\u30ea\u52b9\u7387\u306e\u7279\u5fb4<\/h4>\n<\/div>\n\n<div id=\"sgb-css-id-79\">\n<p>\u30001. <strong>+\u6f14\u7b97\u5b50\u3068String.concat<\/strong><\/p>\n<\/div>\n\n<div id=\"sgb-css-id-80\">\n<p>\u3000\u3000\u25cf \u6bce\u56de\u65b0\u3057\u3044\u6587\u5b57\u5217\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u751f\u6210<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-81\">\n<p>\u3000\u3000\u25cf \u30ac\u30d9\u30fc\u30b8\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u306e\u8ca0\u8377\u304c\u9ad8\u3044<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-82\">\n<p>\u3000\u3000\u25cf \u30e1\u30e2\u30ea\u306e\u65ad\u7247\u5316\u304c\u767a\u751f\u3057\u3084\u3059\u3044<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-83\">\n<p>\u30002. <strong>StringBuilder\/StringBuffer<\/strong><\/p>\n<\/div>\n\n<div id=\"sgb-css-id-84\">\n<p>\u3000\u3000\u25cf \u53ef\u5909\u30d0\u30c3\u30d5\u30a1\u3092\u4f7f\u7528<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-85\">\n<p>\u3000\u3000\u25cf \u5fc5\u8981\u306b\u5fdc\u3058\u3066\u30d0\u30c3\u30d5\u30a1\u30b5\u30a4\u30ba\u3092\u62e1\u5f35<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-86\">\n<p>\u3000\u3000\u25cf \u6700\u5c0f\u9650\u306e\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u751f\u6210<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-87\">\n<h3 class=\"wp-block-heading\" id=\"i-20\">3.3 \u30eb\u30fc\u30d7\u51e6\u7406\u3067\u306e\u6319\u52d5\u306e\u9055\u3044<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-88\">\n<p>\u30eb\u30fc\u30d7\u51e6\u7406\u306b\u304a\u3051\u308b\u5404\u65b9\u6cd5\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u7279\u6027\u3092\u691c\u8a3c\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u5927\u91cf\u306e\u6587\u5b57\u5217\u7d50\u5408\u3092\u30c6\u30b9\u30c8\npublic static void testLoopPerformance() {\n    final int LOOP_COUNT = 100000;\n    final String TEST_STRING = \"test\";\n\n    \/\/ StringBuilder\n    long start = System.currentTimeMillis();\n    StringBuilder sb = new StringBuilder(LOOP_COUNT * TEST_STRING.length());\n    for (int i = 0; i &lt; LOOP_COUNT; i++) {\n        sb.append(TEST_STRING);\n    }\n    String result1 = sb.toString();\n    System.out.println(\"StringBuilder: \" + (System.currentTimeMillis() - start) + \"ms\");\n\n    \/\/ + \u6f14\u7b97\u5b50\n    start = System.currentTimeMillis();\n    String result2 = \"\";\n    for (int i = 0; i &lt; LOOP_COUNT; i++) {\n        result2 += TEST_STRING;\n    }\n    System.out.println(\"+ \u6f14\u7b97\u5b50: \" + (System.currentTimeMillis() - start) + \"ms\");\n}<\/pre>\n\n\n<div id=\"sgb-css-id-89\">\n<h4 class=\"wp-block-heading\" id=\"i-21\">\u30eb\u30fc\u30d7\u51e6\u7406\u3067\u306e\u91cd\u8981\u306a\u30dd\u30a4\u30f3\u30c8<\/h4>\n<\/div>\n\n<div id=\"sgb-css-id-90\">\n<p>\u30001. <strong>\u521d\u671f\u5bb9\u91cf\u306e\u6700\u9069\u5316<\/strong><\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u52b9\u7387\u7684\u306a\u521d\u671f\u5bb9\u91cf\u8a2d\u5b9a\nStringBuilder sb = new StringBuilder(expectedSize);<\/pre>\n\n\n<div id=\"sgb-css-id-91\">\n<p>\u30002. <strong><strong>\u30e1\u30e2\u30ea\u4f7f\u7528\u306e\u30d1\u30bf\u30fc\u30f3<\/strong><\/strong><\/p>\n<\/div>\n\n<div id=\"sgb-css-id-92\">\n<p>\u3000\u3000\u25cf <code>+\u6f14\u7b97\u5b50<\/code>\uff1a O(n\u00b2)\u306e\u6642\u9593\u8907\u96d1\u5ea6<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-93\">\n<p>\u3000\u3000\u25cf <code>StringBuilder\/StringBuffer<\/code>\uff1a \u307b\u307cO(n)\u306e\u6642\u9593\u8907\u96d1\u5ea6<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-94\">\n<p>\u30003. <strong>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3078\u306e\u5f71\u97ff\u8981\u56e0<\/strong><\/p>\n<\/div>\n\n<div id=\"sgb-css-id-95\">\n<p>\u3000\u3000\u25cf \u30eb\u30fc\u30d7\u306e\u53cd\u5fa9\u56de\u6570<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-96\">\n<p>\u3000\u3000\u25cf \u7d50\u5408\u3059\u308b\u6587\u5b57\u5217\u306e\u9577\u3055<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-97\">\n<p>\u3000\u3000\u25cf \u521d\u671f\u5bb9\u91cf\u306e\u8a2d\u5b9a<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-98\">\n<p>\u3000\u3000\u25cf \u30ac\u30d9\u30fc\u30b8\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u306e\u983b\u5ea6<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-99\">\n<h4 class=\"wp-block-heading\" id=\"i-22\">\u5b9f\u8df5\u7684\u306a\u30a2\u30c9\u30d0\u30a4\u30b9<\/h4>\n<\/div>\n\n<div id=\"sgb-css-id-100\">\n<p>\u3000\u3000\u25cf \u77ed\u3044\u30eb\u30fc\u30d7\uff0810\u56de\u672a\u6e80\uff09\uff1a \u3069\u306e\u65b9\u6cd5\u3067\u3082\u5927\u304d\u306a\u5dee\u306f\u306a\u3044<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-101\">\n<p>\u3000\u3000\u25cf \u4e2d\u898f\u6a21\u30eb\u30fc\u30d7\uff08100\u56de\u672a\u6e80\uff09\uff1a StringBuilder\u3092\u63a8\u5968<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-102\">\n<p>\u3000\u3000\u25cf \u5927\u898f\u6a21\u30eb\u30fc\u30d7\uff081000\u56de\u4ee5\u4e0a\uff09\uff1a \u9069\u5207\u306a\u521d\u671f\u5bb9\u91cf\u3092\u8a2d\u5b9a\u3057\u305fStringBuilder<\/p>\n<\/div>\n\n\n<p>\u3000\u3000\u25cf \u30de\u30eb\u30c1\u30b9\u30ec\u30c3\u30c9\u74b0\u5883\uff1a StringBuffer\u3092\u4f7f\u7528<\/p>\n\n\n<div id=\"sgb-css-id-103\">\n<p>\u4ee5\u4e0a\u306e\u6bd4\u8f03\u7d50\u679c\u304b\u3089\u3001\u4e00\u822c\u7684\u306a\u7528\u9014\u3067\u306fStringBuilder\u304c\u6700\u3082\u512a\u308c\u305f\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u793a\u3059\u3053\u3068\u304c\u5206\u304b\u308a\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3053\u308c\u3089\u306e\u77e5\u898b\u3092\u57fa\u306b\u3001\u5177\u4f53\u7684\u306a\u30e6\u30fc\u30b9\u30b1\u30fc\u30b9\u3054\u3068\u306e\u6700\u9069\u306a\u9078\u629e\u65b9\u6cd5\u3092\u898b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-104\">\n<h2 class=\"wp-block-heading\" id=\"i-23\">\uff14\uff0e\u30e6\u30fc\u30b9\u30b1\u30fc\u30b9\u5225\uff1a\u6700\u9069\u306a\u6587\u5b57\u5217\u7d50\u5408\u306e\u9078\u3073\u65b9<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-105\">\n<h3 class=\"wp-block-heading\" id=\"i-24\">4.1 \u5c11\u91cf\u306e\u6587\u5b57\u5217\u7d50\u5408\u306a\u3089\u30b7\u30f3\u30d7\u30eb\u306b<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-106\">\n<p>\u5c11\u91cf\u306e\u6587\u5b57\u5217\u7d50\u5408\u3067\u306f\u3001\u53ef\u8aad\u6027\u3068\u30e1\u30f3\u30c6\u30ca\u30f3\u30b9\u6027\u3092\u91cd\u8996\u3057\u305f\u9078\u629e\u304c\u63a8\u5968\u3055\u308c\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-107\">\n<h4 class=\"wp-block-heading\" id=\"i-25\">\u63a8\u5968\u3055\u308c\u308b\u65b9\u6cd5<\/h4>\n<\/div>\n\n<div id=\"sgb-css-id-108\">\n<p>\u30001. <strong>+\u6f14\u7b97\u5b50<\/strong><\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u7c21\u5358\u306a\u6587\u5b57\u5217\u7d50\u5408\uff082-3\u500b\u7a0b\u5ea6\uff09\nString firstName = \"\u5c71\u7530\";\nString lastName = \"\u592a\u90ce\";\nString fullName = firstName + \" \" + lastName;  \/\/ \u8aad\u307f\u3084\u3059\u3044\n\n\/\/ \u5909\u6570\u3068\u6587\u5b57\u5217\u306e\u6df7\u5728\nint age = 25;\nString message = \"\u79c1\u306f\" + fullName + \"\u3001\" + age + \"\u6b73\u3067\u3059\u3002\";<\/pre>\n\n\n<div id=\"sgb-css-id-109\">\n<p>\u30002. <strong>String.join<\/strong><\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u914d\u5217\u3084\u30ea\u30b9\u30c8\u306e\u8981\u7d20\u3092\u7d50\u5408\nString[] parts = {\"\u6771\u4eac\u90fd\", \"\u6e0b\u8c37\u533a\", \"\u4ee3\u3005\u6728\"};\nString address = String.join(\" \", parts);  \/\/ \"\u6771\u4eac\u90fd \u6e0b\u8c37\u533a \u4ee3\u3005\u6728\"\n\n\/\/ \u8907\u6570\u306e\u6587\u5b57\u5217\u3092\u6574\u5f62\u3057\u3066\u7d50\u5408\nList&lt;String&gt; items = Arrays.asList(\"\u308a\u3093\u3054\", \"\u30d0\u30ca\u30ca\", \"\u30aa\u30ec\u30f3\u30b8\");\nString itemList = String.join(\"\u3001\", items);  \/\/ \"\u308a\u3093\u3054\u3001\u30d0\u30ca\u30ca\u3001\u30aa\u30ec\u30f3\u30b8\"<\/pre>\n\n\n<div id=\"sgb-css-id-113\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:var(--wp--preset--color--sango-main);color:#FFF\" class=\"sgb-box-simple__title\">\u9078\u629e\u306e\u5224\u65ad\u57fa\u6e96<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:var(--wp--preset--color--sango-main);background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-110\">\n<li>\u7d50\u5408\u3059\u308b\u6587\u5b57\u5217\u306e\u6570\u304c5\u500b\u672a\u6e80<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-111\">\n<li>\u30eb\u30fc\u30d7\u51e6\u7406\u3092\u542b\u307e\u306a\u3044<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-112\">\n<li>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u304c\u91cd\u8981\u3067\u306a\u3044\u5834\u9762<\/li>\n<\/div>\n\n\n<li>\u30b3\u30fc\u30c9\u306e\u53ef\u8aad\u6027\u304c\u91cd\u8981<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-114\">\n<h3 class=\"wp-block-heading\" id=\"i-26\">4.2 \u5927\u91cf\u30c7\u30fc\u30bf\u51e6\u7406\u6642\u306e\u63a8\u5968\u30a2\u30d7\u30ed\u30fc\u30c1<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-115\">\n<p>\u5927\u91cf\u306e\u30c7\u30fc\u30bf\u3092\u6271\u3046\u5834\u5408\u306f\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3068\u52b9\u7387\u6027\u3092\u91cd\u8996\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-116\">\n<h4 class=\"wp-block-heading\" id=\"i-27\">StringBuilder\u306e\u52b9\u7387\u7684\u306a\u4f7f\u7528<\/h4>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u521d\u671f\u5bb9\u91cf\u3092\u9069\u5207\u306b\u8a2d\u5b9a\nint expectedSize = 1000;\nStringBuilder sb = new StringBuilder(expectedSize);\n\n\/\/ \u5927\u91cf\u30c7\u30fc\u30bf\u306e\u52b9\u7387\u7684\u306a\u51e6\u7406\nList&lt;String&gt; largeDataSet = getLargeDataSet();  \/\/ \u5927\u91cf\u306e\u30c7\u30fc\u30bf\u3092\u60f3\u5b9a\nfor (String data : largeDataSet) {\n    sb.append(data)\n      .append(\"\\n\");\n}\nString result = sb.toString();\n\n\/\/ \u30d5\u30a1\u30a4\u30eb\u51e6\u7406\u3067\u306e\u4f7f\u7528\u4f8b\npublic String readFileContent(String filePath) throws IOException {\n    StringBuilder content = new StringBuilder();\n    try (BufferedReader reader = new BufferedReader(new FileReader(filePath))) {\n        String line;\n        while ((line = reader.readLine()) != null) {\n            content.append(line).append(\"\\n\");\n        }\n    }\n    return content.toString();\n}<\/pre>\n\n\n<div id=\"sgb-css-id-120\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:var(--wp--preset--color--sango-main);color:#FFF\" class=\"sgb-box-simple__title\">\u9078\u629e\u306e\u5224\u65ad\u57fa\u6e96<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:var(--wp--preset--color--sango-main);background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-117\">\n<li>\u5927\u91cf\u306e\u6587\u5b57\u5217\u3092\u51e6\u7406\u3059\u308b<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-118\">\n<li>\u30eb\u30fc\u30d7\u51e6\u7406\u3092\u542b\u3080<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-119\">\n<li>\u30e1\u30e2\u30ea\u52b9\u7387\u304c\u91cd\u8981<\/li>\n<\/div>\n\n\n<li>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u304c\u91cd\u8981\u306a\u5834\u9762<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-121\">\n<h3 class=\"wp-block-heading\" id=\"i-28\">4.3 \u30de\u30eb\u30c1\u30b9\u30ec\u30c3\u30c9\u74b0\u5883\u3067\u306e\u5b89\u5168\u306a\u5b9f\u88c5<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-122\">\n<p>\u30de\u30eb\u30c1\u30b9\u30ec\u30c3\u30c9\u74b0\u5883\u3067\u306f\u3001\u30b9\u30ec\u30c3\u30c9\u30bb\u30fc\u30d5\u30c6\u30a3\u3092\u6700\u512a\u5148\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-123\">\n<h4 class=\"wp-block-heading\" id=\"i-29\">StringBuffer\u306e\u9069\u5207\u306a\u4f7f\u7528<\/h4>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u5171\u6709\u30ea\u30bd\u30fc\u30b9\u3068\u3057\u3066\u306e\u6587\u5b57\u5217\u30d0\u30c3\u30d5\u30a1\npublic class ThreadSafeLogger {\n    private final StringBuffer log = new StringBuffer();\n\n    public synchronized void appendLog(String message) {\n        log.append(\"[\")\n           .append(System.currentTimeMillis())\n           .append(\"] \")\n           .append(message)\n           .append(\"\\n\");\n    }\n\n    public String getLog() {\n        return log.toString();\n    }\n}\n\n\/\/ \u4f7f\u7528\u4f8b\nclass LoggerTest {\n    public static void main(String[] args) {\n        ThreadSafeLogger logger = new ThreadSafeLogger();\n\n        \/\/ \u8907\u6570\u30b9\u30ec\u30c3\u30c9\u304b\u3089\u306e\u30ed\u30b0\u8ffd\u52a0\n        Runnable logTask = () -&gt; {\n            for (int i = 0; i &lt; 100; i++) {\n                logger.appendLog(\"Message from \" + Thread.currentThread().getName());\n            }\n        };\n\n        Thread t1 = new Thread(logTask, \"Thread-1\");\n        Thread t2 = new Thread(logTask, \"Thread-2\");\n        t1.start();\n        t2.start();\n    }\n}<\/pre>\n\n\n<div id=\"sgb-css-id-124\">\n<h4 class=\"wp-block-heading\" id=\"i-30\">\u30ab\u30b9\u30bf\u30e0\u30ed\u30c3\u30af\u306b\u3088\u308b\u5236\u5fa1<\/h4>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u3088\u308a\u7d30\u304b\u3044\u7c92\u5ea6\u3067\u306e\u30ed\u30c3\u30af\u5236\u5fa1\u304c\u5fc5\u8981\u306a\u5834\u5408\npublic class CustomThreadSafeBuilder {\n    private final StringBuffer buffer = new StringBuffer();\n    private final Object lock = new Object();\n\n    public void appendWithLock(String str) {\n        synchronized(lock) {\n            buffer.append(str);\n        }\n    }\n\n    public void appendWithoutLock(String str) {\n        buffer.append(str);  \/\/ \u975e\u540c\u671f\u64cd\u4f5c\u304c\u8a31\u5bb9\u3055\u308c\u308b\u5834\u5408\n    }\n}<\/pre>\n\n\n<div id=\"sgb-css-id-128\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:var(--wp--preset--color--sango-main);color:#FFF\" class=\"sgb-box-simple__title\">\u9078\u629e\u306e\u5224\u65ad\u57fa\u6e96<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:var(--wp--preset--color--sango-main);background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-125\">\n<li>\u30de\u30eb\u30c1\u30b9\u30ec\u30c3\u30c9\u74b0\u5883\u3067\u306e\u5b9f\u884c<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-126\">\n<li>\u5171\u6709\u30ea\u30bd\u30fc\u30b9\u3068\u3057\u3066\u306e\u6587\u5b57\u5217\u64cd\u4f5c<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-127\">\n<li>\u30c7\u30fc\u30bf\u306e\u6574\u5408\u6027\u304c\u91cd\u8981<\/li>\n<\/div>\n\n\n<li>\u540c\u671f\u51e6\u7406\u306e\u30aa\u30fc\u30d0\u30fc\u30d8\u30c3\u30c9\u304c\u8a31\u5bb9\u3055\u308c\u308b<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-129\">\n<p>\u4ee5\u4e0a\u306e\u30e6\u30fc\u30b9\u30b1\u30fc\u30b9\u5225\u30ac\u30a4\u30c9\u30e9\u30a4\u30f3\u3092\u53c2\u8003\u306b\u3001\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u306e\u8981\u4ef6\u306b\u6700\u9069\u306a\u6587\u5b57\u5217\u7d50\u5408\u65b9\u6cd5\u3092\u9078\u629e\u3057\u3066\u304f\u3060\u3055\u3044\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3088\u308a\u5b9f\u8df5\u7684\u306a\u30b3\u30fc\u30c9\u4f8b\u3068\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3092\u898b\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-130\">\n<h2 class=\"wp-block-heading\" id=\"i-31\">\uff15\uff0e\u6587\u5b57\u5217\u7d50\u5408\u306e\u5b9f\u8df5\u7684\u306a\u30b3\u30fc\u30c9\u3068\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-131\">\n<h3 class=\"wp-block-heading\" id=\"i-32\">5.1 \u52b9\u7387\u7684\u306a\u30b3\u30fc\u30c9\u4f8b\u3068\u89e3\u8aac<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-132\">\n<h4 class=\"wp-block-heading\" id=\"i-33\">\u30ed\u30b0\u51fa\u529b\u306e\u6700\u9069\u5316<\/h4>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">public class OptimizedLogger {\n    private static final int INITIAL_BUFFER_SIZE = 256;\n\n    public static String createLogMessage(String level, String message, Exception e) {\n        \/\/ \u5fc5\u8981\u306a\u30d0\u30c3\u30d5\u30a1\u30b5\u30a4\u30ba\u3092\u4e88\u6e2c\u3057\u3066\u521d\u671f\u5316\n        StringBuilder sb = new StringBuilder(INITIAL_BUFFER_SIZE)\n            .append('[')\n            .append(LocalDateTime.now())\n            .append(\"] [\")\n            .append(level)\n            .append(\"] \")\n            .append(message);\n\n        if (e != null) {\n            sb.append(\"\\nException: \")\n              .append(e.getClass().getName())\n              .append(\": \")\n              .append(e.getMessage());\n        }\n\n        return sb.toString();\n    }\n}<\/pre>\n\n\n<div id=\"sgb-css-id-133\">\n<h4 class=\"wp-block-heading\" id=\"i-34\">\u5927\u898f\u6a21\u306a\u30c7\u30fc\u30bf\u51e6\u7406<\/h4>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">public class DataProcessor {\n    private static final int CHUNK_SIZE = 1000;\n\n    public String processLargeDataSet(List&lt;String&gt; dataSet) {\n        \/\/ \u30c7\u30fc\u30bf\u30b5\u30a4\u30ba\u306b\u57fa\u3065\u3044\u3066\u521d\u671f\u5bb9\u91cf\u3092\u8a2d\u5b9a\n        int estimatedSize = dataSet.size() * 20; \/\/ 1\u9805\u76ee\u3042\u305f\u308a\u5e73\u574720\u6587\u5b57\u3068\u4eee\u5b9a\n        StringBuilder result = new StringBuilder(estimatedSize);\n\n        \/\/ \u30c1\u30e3\u30f3\u30af\u5358\u4f4d\u3067\u306e\u51e6\u7406\n        for (int i = 0; i &lt; dataSet.size(); i += CHUNK_SIZE) {\n            int end = Math.min(i + CHUNK_SIZE, dataSet.size());\n            List&lt;String&gt; chunk = dataSet.subList(i, end);\n\n            \/\/ \u30c1\u30e3\u30f3\u30af\u306e\u51e6\u7406\n            processChunk(chunk, result);\n        }\n\n        return result.toString();\n    }\n\n    private void processChunk(List&lt;String&gt; chunk, StringBuilder result) {\n        for (String item : chunk) {\n            result.append(item)\n                  .append(',')\n                  .append(' ');\n        }\n    }\n}<\/pre>\n\n\n<div id=\"sgb-css-id-134\">\n<h3 class=\"wp-block-heading\" id=\"i-35\">5.2 \u3088\u304f\u3042\u308b\u9593\u9055\u3044\u3068\u5bfe\u51e6\u6cd5<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-135\">\n<h4 class=\"wp-block-heading\" id=\"i-36\">1. \u30eb\u30fc\u30d7\u5185\u3067\u306e\u4e0d\u9069\u5207\u306a\u6587\u5b57\u5217\u7d50\u5408<\/h4>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u60aa\u3044\u4f8b\npublic String badConcatenation(List&lt;String&gt; items) {\n    String result = \"\";\n    for (String item : items) {\n        result += item + \", \";  \/\/ \u6bce\u56de\u65b0\u3057\u3044\u6587\u5b57\u5217\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304c\u751f\u6210\u3055\u308c\u308b\n    }\n    return result;\n}\n\n\/\/ \u826f\u3044\u4f8b\npublic String goodConcatenation(List&lt;String&gt; items) {\n    if (items.isEmpty()) {\n        return \"\";\n    }\n    StringBuilder sb = new StringBuilder(items.size() * 20);\n    for (String item : items) {\n        sb.append(item).append(\", \");\n    }\n    return sb.substring(0, sb.length() - 2);  \/\/ \u6700\u5f8c\u306e\u30ab\u30f3\u30de\u3068\u30b9\u30da\u30fc\u30b9\u3092\u524a\u9664\n}<\/pre>\n\n\n<div id=\"sgb-css-id-136\">\n<h4 class=\"wp-block-heading\" id=\"i-37\">2. \u4e0d\u9069\u5207\u306a\u521d\u671f\u5bb9\u91cf\u8a2d\u5b9a<\/h4>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u60aa\u3044\u4f8b\nStringBuilder sb = new StringBuilder();  \/\/ \u30c7\u30d5\u30a9\u30eb\u30c8\u306e\u5c0f\u3055\u3044\u5bb9\u91cf\n\n\/\/ \u826f\u3044\u4f8b\n\/\/ \u5fc5\u8981\u306a\u5bb9\u91cf\u3092\u8a08\u7b97\u3057\u3066\u8a2d\u5b9a\nint requiredCapacity = dataSize * averageItemLength;\nStringBuilder sb = new StringBuilder(requiredCapacity);<\/pre>\n\n\n<div id=\"sgb-css-id-137\">\n<h4 class=\"wp-block-heading\" id=\"i-38\">3. \u4e0d\u8981\u306aStringBuilder\/StringBuffer\u306e\u4f7f\u7528<\/h4>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u60aa\u3044\u4f8b\nString name = new StringBuilder().append(\"Hello\").append(\" \").append(\"World\").toString();\n\n\/\/ \u826f\u3044\u4f8b\nString name = \"Hello\" + \" \" + \"World\";  \/\/ \u30b3\u30f3\u30d1\u30a4\u30e9\u304c\u6700\u9069\u5316\u3057\u3066\u304f\u308c\u308b<\/pre>\n\n\n<div id=\"sgb-css-id-138\">\n<h3 class=\"wp-block-heading\" id=\"i-39\">5.3 \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u30c1\u30e5\u30fc\u30cb\u30f3\u30b0\u306e\u30dd\u30a4\u30f3\u30c8<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-139\">\n<h4 class=\"wp-block-heading\" id=\"i-40\">\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u306e\u6700\u9069\u5316<\/h4>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">public class StringConcatOptimizer {\n    \/\/ \u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3092\u76e3\u8996\u3059\u308b\u30e6\u30fc\u30c6\u30a3\u30ea\u30c6\u30a3\u30e1\u30bd\u30c3\u30c9\n    private static long getMemoryUsage() {\n        Runtime runtime = Runtime.getRuntime();\n        return runtime.totalMemory() - runtime.freeMemory();\n    }\n\n    \/\/ \u6700\u9069\u5316\u3055\u308c\u305f\u30d0\u30c3\u30d5\u30a1\u30b5\u30a4\u30ba\u8a08\u7b97\n    private static int calculateOptimalBufferSize(List&lt;String&gt; inputs) {\n        \/\/ \u30b5\u30f3\u30d7\u30ea\u30f3\u30b0\u306b\u3088\u308b\u5e73\u5747\u9577\u306e\u7b97\u51fa\n        int sampleSize = Math.min(inputs.size(), 100);\n        double avgLength = inputs.stream()\n                                .limit(sampleSize)\n                                .mapToInt(String::length)\n                                .average()\n                                .orElse(16);  \/\/ \u30c7\u30d5\u30a9\u30eb\u30c8\u5024\n\n        return (int)(inputs.size() * avgLength * 1.2);  \/\/ 20%\u306e\u30d0\u30c3\u30d5\u30a1\u3092\u8ffd\u52a0\n    }\n\n    \/\/ \u6700\u9069\u5316\u3055\u308c\u305f\u6587\u5b57\u5217\u7d50\u5408\u51e6\u7406\n    public static String optimizedConcat(List&lt;String&gt; inputs, String delimiter) {\n        if (inputs == null || inputs.isEmpty()) {\n            return \"\";\n        }\n\n        if (inputs.size() == 1) {\n            return inputs.get(0);\n        }\n\n        int optimalSize = calculateOptimalBufferSize(inputs);\n        StringBuilder sb = new StringBuilder(optimalSize);\n\n        \/\/ \u30d0\u30c3\u30c1\u51e6\u7406\u306b\u3088\u308b\u52b9\u7387\u5316\n        Iterator&lt;String&gt; iterator = inputs.iterator();\n        sb.append(iterator.next());\n        while (iterator.hasNext()) {\n            sb.append(delimiter).append(iterator.next());\n        }\n\n        return sb.toString();\n    }\n}<\/pre>\n\n\n<div id=\"sgb-css-id-140\">\n<h4 class=\"wp-block-heading\" id=\"i-41\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6539\u5584\u306e\u30c1\u30a7\u30c3\u30af\u30ea\u30b9\u30c8<\/h4>\n<\/div>\n\n<div id=\"sgb-css-id-141\">\n<p>\u30001. <strong>\u521d\u671f\u5bb9\u91cf\u306e\u6700\u9069\u5316<\/strong><\/p>\n<\/div>\n\n<div id=\"sgb-css-id-142\">\n<p>\u3000\u3000\u25cf \u30c7\u30fc\u30bf\u30b5\u30a4\u30ba\u306e\u4e88\u6e2c<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-143\">\n<p>\u3000\u3000\u25cf \u30d0\u30c3\u30d5\u30a1\u30aa\u30fc\u30d0\u30fc\u30d8\u30c3\u30c9\u306e\u8003\u616e<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-144\">\n<p>\u3000\u3000\u25cf \u52d5\u7684\u306a\u5bb9\u91cf\u8a08\u7b97<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-145\">\n<p>\u30002. <strong><strong>\u30e1\u30e2\u30ea\u7ba1\u7406<\/strong><\/strong><\/p>\n<\/div>\n\n<div id=\"sgb-css-id-146\">\n<p>\u3000\u3000\u25cf \u5927\u304d\u306a\u6587\u5b57\u5217\u306e\u5206\u5272\u51e6\u7406<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-147\">\n<p>\u3000\u3000\u25cf \u9069\u5207\u306a\u30ac\u30d9\u30fc\u30b8\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u306e\u30bf\u30a4\u30df\u30f3\u30b0<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-148\">\n<p>\u3000\u3000\u25cf \u30e1\u30e2\u30ea\u30ea\u30fc\u30af\u306e\u9632\u6b62<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-149\">\n<p>\u30003. <strong>\u51e6\u7406\u306e\u52b9\u7387\u5316<\/strong><\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u52b9\u7387\u7684\u306a\u6587\u5b57\u5217\u51e6\u7406\u306e\u4f8b\npublic class StringProcessor {\n    public static String processLargeString(String input, int chunkSize) {\n        StringBuilder result = new StringBuilder(input.length());\n\n        \/\/ \u30c1\u30e3\u30f3\u30af\u5358\u4f4d\u3067\u306e\u51e6\u7406\n        for (int i = 0; i &lt; input.length(); i += chunkSize) {\n            int end = Math.min(i + chunkSize, input.length());\n            String chunk = input.substring(i, end);\n\n            \/\/ \u30c1\u30e3\u30f3\u30af\u306e\u51e6\u7406\n            processChunk(chunk, result);\n\n            \/\/ \u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u306e\u78ba\u8a8d\u3068\u5fc5\u8981\u306b\u5fdc\u3058\u305fGC\u306e\u5b9f\u884c\n            if (getMemoryUsage() &gt; threshold) {\n                System.gc();\n            }\n        }\n\n        return result.toString();\n    }\n\n    private static void processChunk(String chunk, StringBuilder result) {\n        \/\/ \u30c1\u30e3\u30f3\u30af\u5358\u4f4d\u306e\u51e6\u7406\u30ed\u30b8\u30c3\u30af\n    }\n}<\/pre>\n\n\n<div id=\"sgb-css-id-150\">\n<p>\u4ee5\u4e0a\u304c\u3001Java\u3067\u306e\u6587\u5b57\u5217\u7d50\u5408\u306b\u95a2\u3059\u308b\u5b9f\u8df5\u7684\u306a\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3067\u3059\u3002\u3053\u308c\u3089\u306e\u77e5\u8b58\u3092\u6d3b\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u52b9\u7387\u7684\u3067\u4fdd\u5b88\u6027\u306e\u9ad8\u3044\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-151\">\n<h2 class=\"wp-block-heading\" id=\"i-42\">\u307e\u3068\u3081\u3068\u7d50\u8ad6<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-152\">\n<h3 class=\"wp-block-heading\" id=\"i-43\">\u91cd\u8981\u30dd\u30a4\u30f3\u30c8\u306e\u6574\u7406<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-153\">\n<h4 class=\"wp-block-heading\" id=\"i-44\">1. \u6587\u5b57\u5217\u7d50\u5408\u65b9\u6cd5\u306e\u4f7f\u3044\u5206\u3051<\/h4>\n<\/div>\n\n<div id=\"sgb-css-id-154\">\n<p>\u4ee5\u4e0b\u306e\u8868\u3067\u3001\u72b6\u6cc1\u306b\u5fdc\u3058\u305f\u6700\u9069\u306a\u9078\u629e\u65b9\u6cd5\u3092\u307e\u3068\u3081\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"id-55ea115d-c03a-46d7-92c9-22b1e5a03863\"><div id=\"sgb-css-id-155\">\n<figure class=\"wp-block-table\"><table><thead><tr><th>\u72b6\u6cc1<\/th><th>\u63a8\u5968\u3055\u308c\u308b\u65b9\u6cd5<\/th><th>\u7406\u7531<\/th><\/tr><\/thead><tbody><tr><td>\u5c11\u91cf\u306e\u6587\u5b57\u5217\u7d50\u5408\uff082-3\u500b\uff09<\/td><td><code>+<\/code>\u6f14\u7b97\u5b50<\/td><td>\u30b7\u30f3\u30d7\u30eb\u3067\u53ef\u8aad\u6027\u304c\u9ad8\u3044<\/td><\/tr><tr><td>\u30eb\u30fc\u30d7\u5185\u3067\u306e\u7d50\u5408<\/td><td><code>StringBuilder<\/code><\/td><td>\u30e1\u30e2\u30ea\u52b9\u7387\u3068\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u304c\u512a\u308c\u3066\u3044\u308b<\/td><\/tr><tr><td>\u30de\u30eb\u30c1\u30b9\u30ec\u30c3\u30c9\u74b0\u5883<\/td><td><code>StringBuffer<\/code><\/td><td>\u30b9\u30ec\u30c3\u30c9\u30bb\u30fc\u30d5\u306a\u64cd\u4f5c\u304c\u4fdd\u8a3c\u3055\u308c\u308b<\/td><\/tr><tr><td>\u914d\u5217\u30fb\u30ea\u30b9\u30c8\u306e\u7d50\u5408<\/td><td><code>String.join()<\/code><\/td><td>\u53ef\u8aad\u6027\u304c\u9ad8\u304f\u3001\u30e1\u30f3\u30c6\u30ca\u30f3\u30b9\u304c\u5bb9\u6613<\/td><\/tr><tr><td>\u5927\u898f\u6a21\u30c7\u30fc\u30bf\u51e6\u7406<\/td><td>\u6700\u9069\u5316\u3055\u308c\u305f<code>StringBuilder<\/code><\/td><td>\u521d\u671f\u5bb9\u91cf\u8a2d\u5b9a\u306b\u3088\u308b\u52b9\u7387\u7684\u306a\u51e6\u7406<\/td><\/tr><\/tbody><\/table><\/figure>\n<\/div><\/div>\n\n<div id=\"sgb-css-id-156\">\n<h4 class=\"wp-block-heading\" id=\"i-45\">2. \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u306e\u8981\u70b9<\/h4>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">\/\/ \u52b9\u7387\u7684\u306a\u6587\u5b57\u5217\u7d50\u5408\u306e\u5b9f\u88c5\u4f8b\npublic class OptimizedStringConcatenation {\n    \/\/ \u63a8\u5b9a\u30b5\u30a4\u30ba\u306e\u8a08\u7b97\n    private static int estimateSize(List&lt;String&gt; strings) {\n        return strings.stream()\n                     .mapToInt(String::length)\n                     .sum();\n    }\n\n    \/\/ \u6700\u9069\u5316\u3055\u308c\u305f\u7d50\u5408\u51e6\u7406\n    public static String concatenateEfficiently(List&lt;String&gt; strings) {\n        int capacity = estimateSize(strings);\n        StringBuilder sb = new StringBuilder(capacity);\n\n        strings.forEach(sb::append);\n\n        return sb.toString();\n    }\n}<\/pre>\n\n\n<div id=\"sgb-css-id-157\">\n<h4 class=\"wp-block-heading\" id=\"i-46\">3. \u5b9f\u88c5\u6642\u306e\u30c1\u30a7\u30c3\u30af\u30dd\u30a4\u30f3\u30c8<\/h4>\n<\/div>\n\n<div id=\"sgb-css-id-158\">\n<p>\u30001. \u521d\u671f\u8a2d\u8a08\u6642<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-159\">\n<p>\u3000\u3000\u25cf \u7d50\u5408\u3059\u308b\u6587\u5b57\u5217\u306e\u6570\u3068\u9577\u3055\u306e\u898b\u7a4d\u3082\u308a<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-160\">\n<p>\u3000\u3000\u25cf \u30b9\u30ec\u30c3\u30c9\u30bb\u30fc\u30d5\u30c6\u30a3\u306e\u5fc5\u8981\u6027\u306e\u5224\u65ad<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-161\">\n<p>\u3000\u3000\u25cf \u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u306e\u4e88\u6e2c<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-162\">\n<p>\u30002. \u5b9f\u88c5\u6642<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-163\">\n<p>\u3000\u3000\u25cf \u9069\u5207\u306a\u521d\u671f\u5bb9\u91cf\u306e\u8a2d\u5b9a<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-164\">\n<p>\u3000\u3000\u25cf null\u5024\u306e\u9069\u5207\u306a\u51e6\u7406<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-165\">\n<p>\u3000\u3000\u25cf \u4f8b\u5916\u51e6\u7406\u306e\u5b9f\u88c5<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-166\">\n<p>\u30003. \u6700\u9069\u5316\u6642<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-167\">\n<p>\u3000\u3000\u25cf \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u30dc\u30c8\u30eb\u30cd\u30c3\u30af\u7279\u5b9a<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-168\">\n<p>\u3000\u3000\u25cf \u30e1\u30e2\u30ea\u30ea\u30fc\u30af\u306e\u9632\u6b62<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-169\">\n<p>\u3000\u3000\u25cf \u30ac\u30d9\u30fc\u30b8\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u306e\u8003\u616e<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-170\">\n<h3 class=\"wp-block-heading\" id=\"i-47\">\u4eca\u5f8c\u306e\u5b66\u7fd2\u306b\u5411\u3051\u3066<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-171\">\n<h4 class=\"wp-block-heading\" id=\"i-48\">1. \u3055\u3089\u306a\u308b\u5b66\u7fd2\u306e\u305f\u3081\u306e\u30ed\u30fc\u30c9\u30de\u30c3\u30d7<\/h4>\n<\/div>\n\n<div id=\"sgb-css-id-172\">\n<p>\u30001. \u57fa\u790e\u77e5\u8b58\u306e\u5f37\u5316<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-173\">\n<p>\u3000\u3000\u25cf Java\u6587\u5b57\u5217\u51e6\u7406\u306e\u8a73\u7d30\u7406\u89e3<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-174\">\n<p>\u3000\u3000\u25cf \u30e1\u30e2\u30ea\u7ba1\u7406\u306e\u6df1\u3044\u7406\u89e3<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-175\">\n<p>\u3000\u3000\u25cf \u30b3\u30f3\u30ab\u30ec\u30f3\u30b7\u30fc\u306e\u5b66\u7fd2<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-176\">\n<p>\u30002. \u5fdc\u7528\u30b9\u30ad\u30eb<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-177\">\n<p>\u3000\u3000\u25cf \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u30c1\u30e5\u30fc\u30cb\u30f3\u30b0\u624b\u6cd5<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-178\">\n<p>\u3000\u3000\u25cf \u30d7\u30ed\u30d5\u30a1\u30a4\u30ea\u30f3\u30b0\u30c4\u30fc\u30eb\u306e\u4f7f\u7528<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-179\">\n<p>\u3000\u3000\u25cf \u30d9\u30f3\u30c1\u30de\u30fc\u30af\u30c6\u30b9\u30c8\u306e\u5b9f\u65bd<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-180\">\n<p>\u30003. \u5b9f\u8df5\u7684\u306a\u30b9\u30ad\u30eb<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-181\">\n<p>\u3000\u3000\u25cf \u5927\u898f\u6a21\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3067\u306e\u5b9f\u88c5<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-182\">\n<p>\u3000\u3000\u25cf \u30de\u30a4\u30af\u30ed\u30b5\u30fc\u30d3\u30b9\u3067\u306e\u6d3b\u7528<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-183\">\n<p>\u3000\u3000\u25cf \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u306e\u5b9f\u8df5<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-184\">\n<h4 class=\"wp-block-heading\" id=\"i-49\">2. \u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u306e\u5b9f\u88c5\u4f8b<\/h4>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">public class StringConcatBestPractices {\n    \/\/ 1. \u52b9\u7387\u7684\u306a\u30eb\u30fc\u30d7\u51e6\u7406\n    public static String processLargeData(List&lt;String&gt; data) {\n        return data.stream()\n                  .filter(Objects::nonNull)\n                  .collect(StringBuilder::new,\n                          StringBuilder::append,\n                          StringBuilder::append)\n                  .toString();\n    }\n\n    \/\/ 2. \u30b9\u30ec\u30c3\u30c9\u30bb\u30fc\u30d5\u306a\u5b9f\u88c5\n    private static final ThreadLocal&lt;StringBuilder&gt; threadLocalBuilder =\n        ThreadLocal.withInitial(() -&gt; new StringBuilder(1024));\n\n    public static String threadSafeConcat(List&lt;String&gt; strings) {\n        StringBuilder sb = threadLocalBuilder.get();\n        sb.setLength(0);\n        strings.forEach(sb::append);\n        return sb.toString();\n    }\n\n    \/\/ 3. \u30e1\u30e2\u30ea\u52b9\u7387\u306e\u826f\u3044\u5b9f\u88c5\n    public static String memoryEfficientConcat(Iterator&lt;String&gt; iterator) {\n        if (!iterator.hasNext()) {\n            return \"\";\n        }\n\n        String first = iterator.next();\n        if (!iterator.hasNext()) {\n            return first;\n        }\n\n        StringBuilder sb = new StringBuilder(first);\n        while (iterator.hasNext()) {\n            sb.append(iterator.next());\n        }\n        return sb.toString();\n    }\n}<\/pre>\n\n\n\n<h3 class=\"wp-block-heading\" id=\"i-50\">\u6700\u7d42\u7684\u306a\u63a8\u5968\u4e8b\u9805<\/h3>\n\n\n<div id=\"sgb-css-id-185\">\n<p><strong>1. \u8a2d\u8a08\u6bb5\u968e\u3067\u8003\u616e\u3059\u3079\u304d\u3053\u3068<\/strong><\/p>\n<\/div>\n\n<div id=\"sgb-css-id-186\">\n<p>\u3000\u25cf \u6587\u5b57\u5217\u64cd\u4f5c\u306e\u898f\u6a21\u3068\u983b\u5ea6<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-187\">\n<p>\u3000\u25cf \u30b9\u30ec\u30c3\u30c9\u30bb\u30fc\u30d5\u30c6\u30a3\u306e\u8981\u4ef6<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-188\">\n<p>\u3000\u25cf \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u8981\u4ef6<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-189\">\n<p>\u3000\u25cf \u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u306e\u5236\u7d04<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-190\">\n<p><strong>2. \u5b9f\u88c5\u6642\u306e\u6ce8\u610f\u70b9<\/strong><\/p>\n<\/div>\n\n<div id=\"sgb-css-id-191\">\n<p>\u3000\u25cf \u9069\u5207\u306a\u65b9\u6cd5\u306e\u9078\u629e<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-192\">\n<p>\u3000\u25cf \u521d\u671f\u5bb9\u91cf\u306e\u6700\u9069\u5316<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-193\">\n<p>\u3000\u25cf \u30a8\u30e9\u30fc\u51e6\u7406\u306e\u5b9f\u88c5<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-194\">\n<p>\u3000\u25cf \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u8003\u616e<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-195\">\n<p><strong>3. \u904b\u7528\u6642\u306e\u6ce8\u610f\u70b9<\/strong><\/p>\n<\/div>\n\n<div id=\"sgb-css-id-196\">\n<p>\u3000\u25cf \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u30e2\u30cb\u30bf\u30ea\u30f3\u30b0<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-197\">\n<p>\u3000\u25cf \u30e1\u30e2\u30ea\u30ea\u30fc\u30af\u306e\u76e3\u8996<\/p>\n<\/div>\n\n\n<p>\u3000\u25cf \u5b9a\u671f\u7684\u306a\u6700\u9069\u5316<\/p>\n\n\n<div 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