{"id":399,"date":"2024-10-23T14:52:56","date_gmt":"2024-10-23T05:52:56","guid":{"rendered":"https:\/\/dexall.co.jp\/articles\/?p=399"},"modified":"2025-03-24T08:53:19","modified_gmt":"2025-03-23T23:53:19","slug":"%e3%80%90java%e5%88%9d%e5%bf%83%e8%80%85%e5%bf%85%e8%a6%8b%e3%80%91substring%e3%83%9e%e3%82%b9%e3%82%bf%e3%83%bc%e8%ac%9b%e5%ba%a7%ef%bc%9a5%e3%81%a4%e3%81%ae%e6%b4%bb%e7%94%a8%e3%83%86%e3%82%af","status":"publish","type":"post","link":"https:\/\/dexall.co.jp\/articles\/?p=399","title":{"rendered":"\u3010Java\u521d\u5fc3\u8005\u5fc5\u898b\u3011substring\u30de\u30b9\u30bf\u30fc\u8b1b\u5ea7\uff1a5\u3064\u306e\u6d3b\u7528\u30c6\u30af\u30cb\u30c3\u30af\u3068\u6027\u80fd\u6700\u9069\u5316\u306e\u79d8\u8a23"},"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\">1. \u306f\u3058\u3081\u306b\uff1aJava\u306esubstring\u30e1\u30bd\u30c3\u30c9\u3068\u306f<\/a>  <\/li>  <li>    <a href=\"#i-1\">2. substring\u30e1\u30bd\u30c3\u30c9\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-2\">\u69cb\u6587\u3068\u5f15\u6570\u306e\u8aac\u660e<\/a>      <\/li>      <li>        <a href=\"#i-3\">\u7c21\u5358\u306a\u4f8b\u3067\u7406\u89e3\u3059\u308bsubstring\u306e\u52d5\u4f5c<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-4\">\u6ce8\u610f\u70b9<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-5\">3. substring\u306e5\u3064\u306e\u5b9f\u8df5\u7684\u306a\u6d3b\u7528\u30c6\u30af\u30cb\u30c3\u30af<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-6\">\u30c6\u30af\u30cb\u30c3\u30af1\uff1a\u6587\u5b57\u5217\u306e\u4e00\u90e8\u3092\u62bd\u51fa\u3059\u308b<\/a>      <\/li>      <li>        <a href=\"#i-7\">\u30c6\u30af\u30cb\u30c3\u30af2\uff1a\u6587\u5b57\u5217\u306e\u672b\u5c3e\u3092\u53d6\u5f97\u3059\u308b<\/a>      <\/li>      <li>        <a href=\"#i-8\">\u30c6\u30af\u30cb\u30c3\u30af3\uff1a\u7279\u5b9a\u306e\u30d1\u30bf\u30fc\u30f3\u306b\u57fa\u3065\u3044\u3066\u6587\u5b57\u5217\u3092\u5206\u5272\u3059\u308b<\/a>      <\/li>      <li>        <a href=\"#i-9\">\u30c6\u30af\u30cb\u30c3\u30af4\uff1a\u6587\u5b57\u5217\u306e\u7f6e\u63db\u3068\u7d44\u307f\u5408\u308f\u305b\u3066\u4f7f\u7528\u3059\u308b<\/a>      <\/li>      <li>        <a href=\"#i-10\">\u30c6\u30af\u30cb\u30c3\u30af5\uff1a\u6b63\u898f\u8868\u73fe\u3068\u4f75\u7528\u3057\u3066\u3088\u308a\u8907\u96d1\u306a\u62bd\u51fa\u3092\u884c\u3046<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-11\">\u6ce8\u610f\u70b9<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-12\">4. substring\u30e1\u30bd\u30c3\u30c9\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-13\">\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3092\u8003\u616e\u3057\u305fsubstring\u306e\u4f7f\u7528\u65b9\u6cd5<\/a>      <\/li>      <li>        <a href=\"#i-14\">\u5927\u91cf\u306e\u6587\u5b57\u5217\u51e6\u7406\u306b\u304a\u3051\u308b\u52b9\u7387\u7684\u306asubstring\u306e\u4f7f\u3044\u65b9<\/a>      <\/li>      <li>        <a href=\"#i-15\">StringBuilder\u3068\u306e\u4f75\u7528\u306b\u3088\u308b\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u5411\u4e0a\u30c6\u30af\u30cb\u30c3\u30af<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-16\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u306e\u6ce8\u610f\u70b9\u3068\u30c8\u30ec\u30fc\u30c9\u30aa\u30d5<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-17\">5. \u3088\u304f\u3042\u308bsubstring\u4f7f\u7528\u6642\u306e\u30a8\u30e9\u30fc\u3068\u5bfe\u51e6\u6cd5<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-18\">IndexOutOfBoundsException\u3092\u56de\u907f\u3059\u308b\u305f\u3081\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/a>      <\/li>      <li>        <a href=\"#i-19\">null\u6587\u5b57\u5217\u306b\u5bfe\u3059\u308bNullPointerException\u306e\u51e6\u7406\u65b9\u6cd5<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-20\">\u30a8\u30e9\u30fc\u9632\u6b62\u306e\u305f\u3081\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-21\">6. substring\u3068\u95a2\u9023\u3059\u308bJava\u306e\u6587\u5b57\u5217\u64cd\u4f5c\u30e1\u30bd\u30c3\u30c9<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-22\">indexOf()\u3068lastIndexOf()\u3092\u4f7f\u3063\u305f\u52d5\u7684\u306asubstring\u64cd\u4f5c<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-23\">trim()\u3001toLowerCase()\u3001toUpperCase()\u3068\u306e\u7d44\u307f\u5408\u308f\u305b\u6d3b\u7528\u6cd5<\/a>      <\/li>    <\/ul>  <\/li>  <li class=\"last\">    <a href=\"#i-24\">7. \u307e\u3068\u3081\uff1asubstring\u30de\u30b9\u30bf\u30fc\u3078\u306e\u9053<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-25\">\u5b66\u3093\u30605\u3064\u306e\u30c6\u30af\u30cb\u30c3\u30af\u3068\u6700\u9069\u5316\u65b9\u6cd5\u306e\u5fa9\u7fd2<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-26\">\u3055\u3089\u306a\u308b\u6587\u5b57\u5217\u64cd\u4f5c\u30b9\u30ad\u30eb\u5411\u4e0a\u306e\u305f\u3081\u306e\u30ea\u30bd\u30fc\u30b9\u3068\u6b21\u306e\u30b9\u30c6\u30c3\u30d7<\/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\">1. \u306f\u3058\u3081\u306b\uff1aJava\u306esubstring\u30e1\u30bd\u30c3\u30c9\u3068\u306f<\/h2>\n<\/div>\n\n\n<p>Java\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306b\u304a\u3044\u3066\u3001\u6587\u5b57\u5217\u64cd\u4f5c\u306f\u975e\u5e38\u306b\u91cd\u8981\u306a\u8981\u7d20\u3067\u3059\u3002\u305d\u306e\u4e2d\u3067\u3082<code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u6587\u5b57\u5217\u306e\u4e00\u90e8\u3092\u62bd\u51fa\u3059\u308b\u305f\u3081\u306e\u5f37\u529b\u306a\u30c4\u30fc\u30eb\u3068\u3057\u3066\u5e83\u304f\u5229\u7528\u3055\u308c\u3066\u3044\u307e\u3059\u3002<\/p>\n\n\n<div id=\"sgb-css-id-2\">\n<p><code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u6307\u5b9a\u3055\u308c\u305f\u958b\u59cb\u4f4d\u7f6e\u304b\u3089\u7d42\u4e86\u4f4d\u7f6e\u307e\u3067\u306e\u90e8\u5206\u6587\u5b57\u5217\u3092\u8fd4\u3059\u3001Java\u306e<code>String<\/code>\u30af\u30e9\u30b9\u306b\u7d44\u307f\u8fbc\u307e\u308c\u305f\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u3002\u4ee5\u4e0b\u306b\u6587\u5b57\u5217\u306e\u4e00\u90e8\u3092\u62bd\u51fa\u3059\u308b\u4f8b\u3092\u793a\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=\"\">String text = \"Hello, World!\";\nString result = text.substring(0, 5); \/\/ \"Hello\"\u3092\u62bd\u51fa<\/pre>\n\n\n<div id=\"sgb-css-id-3\">\n<p>\u3053\u306e\u30e1\u30bd\u30c3\u30c9\u306e\u91cd\u8981\u6027\u306f\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u5e45\u5e83\u3044\u7528\u9014\u306b\u3042\u308a\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\"><code>substring<\/code> \u306e\u4e3b\u306a\u7528\u9014<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:var(--wp--preset--color--sango-main);background-color:#FFF\">\n<ol class=\"wp-block-list\"><div id=\"sgb-css-id-4\">\n<li>\u30c7\u30fc\u30bf\u89e3\u6790\uff1a\u5927\u91cf\u306e\u30c6\u30ad\u30b9\u30c8\u30c7\u30fc\u30bf\u304b\u3089\u5fc5\u8981\u306a\u60c5\u5831\u3092\u62bd\u51fa\u3059\u308b<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-5\">\n<li>\u30e6\u30fc\u30b6\u30fc\u5165\u529b\u306e\u51e6\u7406\uff1a\u5165\u529b\u3055\u308c\u305f\u6587\u5b57\u5217\u304b\u3089\u7279\u5b9a\u306e\u90e8\u5206\u3092\u53d6\u308a\u51fa\u3059<\/li>\n<\/div>\n\n\n<li>\u30c6\u30ad\u30b9\u30c8\u6574\u5f62\uff1a\u6587\u5b57\u5217\u3092\u9069\u5207\u306a\u9577\u3055\u306b\u5207\u308a\u8a70\u3081\u308b<\/li>\n<\/ol>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-7\">\n<p>\u672c\u8a18\u4e8b\u3067\u306f\u3001<code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u304b\u3089\u30015\u3064\u306e\u5b9f\u8df5\u7684\u306a\u6d3b\u7528\u30c6\u30af\u30cb\u30c3\u30af\u3001\u305d\u3057\u3066\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u307e\u3067\u3001\u5e45\u5e83\u304f\u30ab\u30d0\u30fc\u3057\u3066\u3044\u304d\u307e\u3059\u3002\u3053\u308c\u3089\u306e\u77e5\u8b58\u3092\u8eab\u306b\u3064\u3051\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u52b9\u7387\u7684\u3067\u67d4\u8edf\u306a\u6587\u5b57\u5217\u51e6\u7406\u304c\u53ef\u80fd\u306b\u306a\u308a\u3001Java\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u30b9\u30ad\u30eb\u306e\u5411\u4e0a\u306b\u3064\u306a\u304c\u308b\u3067\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-8\">\n<h2 class=\"wp-block-heading\" id=\"i-1\">2. substring\u30e1\u30bd\u30c3\u30c9\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-9\">\n<p><code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001Java\u306e<code>String<\/code>\u30af\u30e9\u30b9\u306b\u7d44\u307f\u8fbc\u307e\u308c\u305f\u30e1\u30bd\u30c3\u30c9\u3067\u3001\u6587\u5b57\u5217\u306e\u4e00\u90e8\u3092\u62bd\u51fa\u3059\u308b\u305f\u3081\u306b\u4f7f\u7528\u3055\u308c\u307e\u3059\u3002\u3053\u306e\u30e1\u30bd\u30c3\u30c9\u306e\u57fa\u672c\u7684\u306a\u69cb\u6587\u3068\u4f7f\u3044\u65b9\u3092\u7406\u89e3\u3059\u308b\u3053\u3068\u306f\u3001\u52b9\u679c\u7684\u306a\u6587\u5b57\u5217\u64cd\u4f5c\u306e\u7b2c\u4e00\u6b69\u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-10\">\n<h3 class=\"wp-block-heading\" id=\"i-2\">\u69cb\u6587\u3068\u5f15\u6570\u306e\u8aac\u660e<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-11\">\n<p><code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u306b\u306f\u30012\u3064\u306e\u30aa\u30fc\u30d0\u30fc\u30ed\u30fc\u30c9\u3055\u308c\u305f\u30d0\u30fc\u30b8\u30e7\u30f3\u304c\u3042\u308a\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\"><code>substring<\/code> \u306e\u30d0\u30fc\u30b8\u30e7\u30f3<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:var(--wp--preset--color--sango-main);background-color:#FFF\">\n<ol class=\"wp-block-list\"><div id=\"sgb-css-id-12\">\n<li><code>public String substring(int beginIndex)<\/code><\/li>\n<\/div>\n\n\n<li><code>public String substring(int beginIndex, int endIndex)<\/code><\/li>\n<\/ol>\n<\/div><\/div>\n\n\n<div id=\"sgb-css-id-13\">\n<p>\u3053\u308c\u3089\u306e\u5f15\u6570\u306e\u610f\u5473\u306f\u4ee5\u4e0b\u306e\u901a\u308a\u3067\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-15\">\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\">\u5f15\u6570\u306e\u610f\u5473<\/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-14\">\n<li><code>beginIndex<\/code>\uff1a \u62bd\u51fa\u3092\u958b\u59cb\u3059\u308b\u4f4d\u7f6e\uff08\u3053\u306e\u6587\u5b57\u3092\u542b\u3080\uff09<\/li>\n<\/div>\n\n\n<li><code>endIndex<\/code>\uff1a \u62bd\u51fa\u3092\u7d42\u4e86\u3059\u308b\u4f4d\u7f6e\uff08\u3053\u306e\u6587\u5b57\u3092\u542b\u307e\u306a\u3044\uff09<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-16\">\n<p>\u91cd\u8981\u306a\u30dd\u30a4\u30f3\u30c8\u3068\u3057\u3066\u3001Java\u306e\u6587\u5b57\u5217\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u306f0\u304b\u3089\u59cb\u307e\u308b\u3053\u3068\u306b\u6ce8\u610f\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-17\">\n<h3 class=\"wp-block-heading\" id=\"i-3\">\u7c21\u5358\u306a\u4f8b\u3067\u7406\u89e3\u3059\u308bsubstring\u306e\u52d5\u4f5c<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-18\">\n<p>\u4ee5\u4e0b\u306e\u4f8b\u3092\u901a\u3058\u3066\u3001<code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u306e\u52d5\u4f5c\u3092\u898b\u3066\u307f\u307e\u3057\u3087\u3046\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 text = \"Hello, World!\";\n\n\/\/ \u4f8b1: \u30a4\u30f3\u30c7\u30c3\u30af\u30b90\u304b\u30895\u307e\u3067\uff085\u306f\u542b\u307e\u306a\u3044\uff09\u306e\u6587\u5b57\u3092\u62bd\u51fa\nString result1 = text.substring(0, 5);\nSystem.out.println(result1);  \/\/ \u51fa\u529b: Hello\n\n\/\/ \u4f8b2: \u30a4\u30f3\u30c7\u30c3\u30af\u30b97\u304b\u3089\u6587\u5b57\u5217\u306e\u672b\u5c3e\u307e\u3067\u62bd\u51fa\nString result2 = text.substring(7);\nSystem.out.println(result2);  \/\/ \u51fa\u529b: World!\n\n\/\/ \u4f8b3: \u4e00\u6587\u5b57\u3060\u3051\u3092\u62bd\u51fa\nString result3 = text.substring(1, 2);\nSystem.out.println(result3);  \/\/ \u51fa\u529b: e\n\n\/\/ \u4f8b4: \u7a7a\u306e\u6587\u5b57\u5217\u3092\u53d6\u5f97\nString result4 = str.substring(0, 0);\nSystem.out.println(result4);  \/\/ \u51fa\u529b: \"\"\uff08\u7a7a\u6587\u5b57\u5217\uff09\n\n\/\/ \u4f8b5: \u6587\u5b57\u5217\u5168\u4f53\u3092\u53d6\u5f97\nString result5 = str.substring(0);\nSystem.out.println(result5);  \/\/ \u51fa\u529b: \"Hello, World!\"<\/pre>\n\n\n<div id=\"sgb-css-id-19\">\n<h3 class=\"wp-block-heading\" id=\"i-4\">\u6ce8\u610f\u70b9<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-23\">\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:#ffb36b;color:#FFF\" class=\"sgb-box-simple__title\">\u4f7f\u7528\u306e\u969b\u306e\u6ce8\u610f\u70b9<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#ffb36b;background-color:#FFF\">\n<ol class=\"wp-block-list\"><div id=\"sgb-css-id-20\">\n<li><code>beginIndex<\/code>\u306f<code>endIndex<\/code>\u4ee5\u4e0b\u3067\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002\u305d\u3046\u3067\u306a\u3044\u5834\u5408\u3001<code>IndexOutOfBoundsException<\/code>\u304c\u30b9\u30ed\u30fc\u3055\u308c\u308b\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-21\">\n<li>\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u306f\u6587\u5b57\u5217\u306e\u9577\u3055\u4ee5\u5185\u3067\u306a\u3051\u308c\u3070\u306a\u3089\u306a\u3044\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-22\">\n<li><code>endIndex<\/code>\u3092\u7701\u7565\u3059\u308b\u3068\u3001\u6587\u5b57\u5217\u306e\u672b\u5c3e\u307e\u3067\u62bd\u51fa\u3055\u308c\u308b\u3002<\/li>\n<\/div>\n\n\n<li>Java 7\u4ee5\u964d\u3001<code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u65b0\u3057\u3044\u6587\u5b57\u5217\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u4f5c\u6210\u3059\u308b\u3002\u3053\u308c\u306f\u3001\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3068\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306b\u5f71\u97ff\u3092\u4e0e\u3048\u308b\u53ef\u80fd\u6027\u304c\u3042\u308b\u3002<\/li>\n<\/ol>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-24\">\n<p><code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u306e\u57fa\u672c\u3092\u7406\u89e3\u3057\u305f\u3068\u3053\u308d\u3067\u3001\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3088\u308a\u5b9f\u8df5\u7684\u306a\u6d3b\u7528\u30c6\u30af\u30cb\u30c3\u30af\u3092\u5b66\u3093\u3067\u3044\u304d\u307e\u3059\u3002\u3053\u308c\u3089\u306e\u30c6\u30af\u30cb\u30c3\u30af\u3092\u7fd2\u5f97\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u52b9\u7387\u7684\u3067\u67d4\u8edf\u306a\u6587\u5b57\u5217\u64cd\u4f5c\u304c\u53ef\u80fd\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-25\">\n<h2 class=\"wp-block-heading\" id=\"i-5\">3. substring\u306e5\u3064\u306e\u5b9f\u8df5\u7684\u306a\u6d3b\u7528\u30c6\u30af\u30cb\u30c3\u30af<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-26\">\n<p><code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u5358\u7d14\u306a\u90e8\u5206\u6587\u5b57\u5217\u306e\u62bd\u51fa\u4ee5\u4e0a\u306e\u529b\u3092\u6301\u3063\u3066\u3044\u307e\u3059\u3002\u3053\u3053\u3067\u306f\u3001\u5b9f\u969b\u306e\u958b\u767a\u30b7\u30fc\u30f3\u3067\u5f79\u7acb\u30645\u3064\u306e\u5b9f\u8df5\u7684\u306a\u6d3b\u7528\u30c6\u30af\u30cb\u30c3\u30af\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002\u3053\u308c\u3089\u306e\u30c6\u30af\u30cb\u30c3\u30af\u3092\u7fd2\u5f97\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u52b9\u7387\u7684\u3067\u67d4\u8edf\u306a\u6587\u5b57\u5217\u64cd\u4f5c\u304c\u53ef\u80fd\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-27\">\n<h3 class=\"wp-block-heading\" id=\"i-6\">\u30c6\u30af\u30cb\u30c3\u30af1\uff1a\u6587\u5b57\u5217\u306e\u4e00\u90e8\u3092\u62bd\u51fa\u3059\u308b<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-28\">\n<p>\u6700\u3082\u57fa\u672c\u7684\u306a\u4f7f\u7528\u65b9\u6cd5\u3067\u3059\u304c\u3001\u7279\u5b9a\u306e\u4f4d\u7f6e\u304b\u3089\u7279\u5b9a\u306e\u9577\u3055\u306e\u90e8\u5206\u6587\u5b57\u5217\u3092\u53d6\u5f97\u3059\u308b\u306e\u306b\u975e\u5e38\u306b\u6709\u7528\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=\"\">String str = \"JavaProgramming\";\nString sub = str.substring(4, 11);  \/\/ \"Program\"\nSystem.out.println(sub);\n\n\/\/ \u51fa\u529b: Program<\/pre>\n\n\n<div id=\"sgb-css-id-29\">\n<p>\u3053\u306e\u30c6\u30af\u30cb\u30c3\u30af\u306f\u3001\u56fa\u5b9a\u9577\u306e\u30c7\u30fc\u30bf\u3092\u6271\u3046\u969b\u3084\u3001\u7279\u5b9a\u306e\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u306e\u6587\u5b57\u5217\u304b\u3089\u60c5\u5831\u3092\u62bd\u51fa\u3059\u308b\u969b\u306b\u5f79\u7acb\u3061\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-30\">\n<h3 class=\"wp-block-heading\" id=\"i-7\">\u30c6\u30af\u30cb\u30c3\u30af2\uff1a\u6587\u5b57\u5217\u306e\u672b\u5c3e\u3092\u53d6\u5f97\u3059\u308b<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-31\">\n<p>\u6587\u5b57\u5217\u306e\u6700\u5f8c\u306en\u6587\u5b57\u3092\u53d6\u5f97\u3057\u305f\u3044\u5834\u5408\u3001<code>substring<\/code>\u3068<code>length()<\/code>\u30e1\u30bd\u30c3\u30c9\u3092\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u7c21\u5358\u306b\u5b9f\u73fe\u3067\u304d\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 str = \"Hello, World!\";\nString lastFive = str.substring(str.length() - 5);  \/\/ \"orld!\"\nSystem.out.println(lastFive);\n\n\/\/ \u51fa\u529b: orld!<\/pre>\n\n\n<div id=\"sgb-css-id-32\">\n<p>\u3053\u306e\u30c6\u30af\u30cb\u30c3\u30af\u306f\u3001\u30d5\u30a1\u30a4\u30eb\u62e1\u5f35\u5b50\u306e\u53d6\u5f97\u3084\u3001\u6587\u5b57\u5217\u306e\u6700\u5f8c\u306e\u90e8\u5206\u3092\u51e6\u7406\u3059\u308b\u969b\u306b\u4fbf\u5229\u3067\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-33\">\n<h3 class=\"wp-block-heading\" id=\"i-8\">\u30c6\u30af\u30cb\u30c3\u30af3\uff1a\u7279\u5b9a\u306e\u30d1\u30bf\u30fc\u30f3\u306b\u57fa\u3065\u3044\u3066\u6587\u5b57\u5217\u3092\u5206\u5272\u3059\u308b<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-34\">\n<p><code>indexOf()<\/code>\u30e1\u30bd\u30c3\u30c9\u3068\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u7279\u5b9a\u306e\u30d1\u30bf\u30fc\u30f3\u3092\u57fa\u6e96\u306b\u6587\u5b57\u5217\u3092\u5206\u5272\u3067\u304d\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 email = \"user@example.com\";\nString domain = email.substring(email.indexOf(\"@\") + 1);  \/\/ \"example.com\"\nSystem.out.println(domain);\n\n\/\/ \u51fa\u529b: example.com<\/pre>\n\n\n<div id=\"sgb-css-id-35\">\n<p>\u3053\u306e\u65b9\u6cd5\u306f\u3001\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u304b\u3089\u30c9\u30e1\u30a4\u30f3\u90e8\u5206\u3092\u62bd\u51fa\u3057\u305f\u308a\u3001URL\u304b\u3089\u30db\u30b9\u30c8\u540d\u3092\u53d6\u5f97\u3057\u305f\u308a\u3059\u308b\u969b\u306b\u975e\u5e38\u306b\u6709\u7528\u3067\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-36\">\n<h3 class=\"wp-block-heading\" id=\"i-9\">\u30c6\u30af\u30cb\u30c3\u30af4\uff1a\u6587\u5b57\u5217\u306e\u7f6e\u63db\u3068\u7d44\u307f\u5408\u308f\u305b\u3066\u4f7f\u7528\u3059\u308b<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-37\">\n<p><code>substring<\/code>\u3068<code>replace()<\/code>\u30e1\u30bd\u30c3\u30c9\u3092\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u6587\u5b57\u5217\u306e\u4e00\u90e8\u3092\u5225\u306e\u6587\u5b57\u5217\u306b\u7f6e\u304d\u63db\u3048\u308b\u3053\u3068\u304c\u3067\u304d\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 url = \"https:\/\/www.example.com\/path\/to\/resource\";\nString newUrl = \"https:\/\/\" + url.substring(8).replace(\"www.\", \"\");\nSystem.out.println(newUrl);\n\n\/\/ \u51fa\u529b: https:\/\/example.com\/path\/to\/resource<\/pre>\n\n\n<div id=\"sgb-css-id-38\">\n<p>\u3053\u306e\u30c6\u30af\u30cb\u30c3\u30af\u306f\u3001URL\u306e\u6b63\u898f\u5316\u3084\u3001\u7279\u5b9a\u306e\u30d1\u30bf\u30fc\u30f3\u3092\u6301\u3064\u6587\u5b57\u5217\u306e\u5909\u63db\u306b\u5f79\u7acb\u3061\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-39\">\n<h3 class=\"wp-block-heading\" id=\"i-10\">\u30c6\u30af\u30cb\u30c3\u30af5\uff1a\u6b63\u898f\u8868\u73fe\u3068\u4f75\u7528\u3057\u3066\u3088\u308a\u8907\u96d1\u306a\u62bd\u51fa\u3092\u884c\u3046<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-40\">\n<p>\u3088\u308a\u8907\u96d1\u306a\u30d1\u30bf\u30fc\u30f3\u30de\u30c3\u30c1\u30f3\u30b0\u304c\u5fc5\u8981\u306a\u5834\u5408\u3001<code>substring<\/code>\u3092\u6b63\u898f\u8868\u73fe\u3068\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u5f37\u529b\u306a\u6587\u5b57\u5217\u64cd\u4f5c\u304c\u53ef\u80fd\u306b\u306a\u308a\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=\"\">import java.util.regex.Matcher;\nimport java.util.regex.Pattern;\n\npublic class RegexSubstring {\n    public static void main(String[] args) {\n        String text = \"The price is $19.99\";\n        Pattern pattern = Pattern.compile(\"\\\\$([0-9]+\\\\.[0-9]+)\");\n        Matcher matcher = pattern.matcher(text);\n        if (matcher.find()) {\n            String price = matcher.group(1);  \/\/ \"19.99\"\n            System.out.println(\"Extracted price: $\" + price);\n        }\n    }\n}\n\n\/\/ \u51fa\u529b: Extracted price: $19.99<\/pre>\n\n\n<div id=\"sgb-css-id-41\">\n<p>\u3053\u306e\u30c6\u30af\u30cb\u30c3\u30af\u306f\u3001\u8907\u96d1\u306a\u30d5\u30a9\u30fc\u30de\u30c3\u30c8\u306e\u6587\u5b57\u5217\u304b\u3089\u7279\u5b9a\u306e\u60c5\u5831\u3092\u62bd\u51fa\u3059\u308b\u969b\u306b\u975e\u5e38\u306b\u5f37\u529b\u3067\u3059\u3002\u4f8b\u3048\u3070\u3001\u30ed\u30b0\u30d5\u30a1\u30a4\u30eb\u306e\u89e3\u6790\u3084Web\u30b9\u30af\u30ec\u30a4\u30d4\u30f3\u30b0\u306a\u3069\u3067\u6d3b\u7528\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-42\">\n<h3 class=\"wp-block-heading\" id=\"i-11\">\u6ce8\u610f\u70b9<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-45\">\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\">\u4f7f\u7528\u306e\u969b\u306e\u6ce8\u610f\u70b9<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:var(--wp--preset--color--sango-main);background-color:#FFF\">\n<ol class=\"wp-block-list\"><div id=\"sgb-css-id-43\">\n<li>\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u306e\u7bc4\u56f2\u306b\u6ce8\u610f\uff1a<code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3059\u308b\u969b\u306f\u3001\u5e38\u306b\u6587\u5b57\u5217\u306e\u9577\u3055\u3068\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u306e\u7bc4\u56f2\u3092\u610f\u8b58\u3057\u307e\u3057\u3087\u3046\u3002\u7bc4\u56f2\u5916\u306e\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u3092\u6307\u5b9a\u3059\u308b\u3068<code>IndexOutOfBoundsException<\/code>\u304c\u767a\u751f\u3057\u307e\u3059\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-44\">\n<li>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u8003\u616e\uff1a\u5927\u91cf\u306e\u6587\u5b57\u5217\u51e6\u7406\u3092\u884c\u3046\u5834\u5408\u3001<code>substring<\/code>\u306e\u983b\u7e41\u306a\u4f7f\u7528\u306f\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306b\u5f71\u97ff\u3092\u4e0e\u3048\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002\u305d\u306e\u3088\u3046\u306a\u5834\u5408\u306f\u3001<code>StringBuilder<\/code>\u306e\u4f7f\u7528\u3092\u691c\u8a0e\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/li>\n<\/div>\n\n\n<li>\u6b63\u898f\u8868\u73fe\u306e\u9069\u5207\u306a\u4f7f\u7528\uff1a\u6b63\u898f\u8868\u73fe\u306f\u5f37\u529b\u3067\u3059\u304c\u3001\u8907\u96d1\u306b\u306a\u308a\u3059\u304e\u308b\u3068\u53ef\u8aad\u6027\u3068\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u304c\u4f4e\u4e0b\u3059\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002\u5358\u7d14\u306a\u30b1\u30fc\u30b9\u3067\u306f<code>substring<\/code>\u3068\u57fa\u672c\u7684\u306a\u6587\u5b57\u5217\u30e1\u30bd\u30c3\u30c9\u306e\u7d44\u307f\u5408\u308f\u305b\u3067\u5341\u5206\u306a\u5834\u5408\u304c\u591a\u3044\u3067\u3059\u3002<\/li>\n<\/ol>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-46\">\n<p>\u3053\u308c\u3089\u306e\u5b9f\u8df5\u7684\u306a\u30c6\u30af\u30cb\u30c3\u30af\u3092\u7fd2\u5f97\u3057\u3001\u9069\u5207\u306b\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u52b9\u7387\u7684\u3067\u67d4\u8edf\u306a\u6587\u5b57\u5217\u64cd\u4f5c\u304c\u53ef\u80fd\u306b\u306a\u308a\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001<code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u898b\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-47\">\n<h2 class=\"wp-block-heading\" id=\"i-12\">4. substring\u30e1\u30bd\u30c3\u30c9\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-48\">\n<p><code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u4fbf\u5229\u306a\u6587\u5b57\u5217\u64cd\u4f5c\u30c4\u30fc\u30eb\u3067\u3059\u304c\u3001\u5927\u898f\u6a21\u306a\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3084\u9ad8\u8ca0\u8377\u306a\u74b0\u5883\u3067\u306f\u3001\u305d\u306e\u4f7f\u7528\u65b9\u6cd5\u304c\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306b\u5927\u304d\u306a\u5f71\u97ff\u3092\u4e0e\u3048\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u3053\u3067\u306f\u3001<code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u30c6\u30af\u30cb\u30c3\u30af\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-49\">\n<h3 class=\"wp-block-heading\" id=\"i-13\">\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3092\u8003\u616e\u3057\u305fsubstring\u306e\u4f7f\u7528\u65b9\u6cd5<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-50\">\n<p>Java 7\u4ee5\u964d\u3001<code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u65b0\u3057\u3044\u6587\u5b57\u5217\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u4f5c\u6210\u3057\u307e\u3059\u3002\u3053\u308c\u306f\u3001\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3068\u30ac\u30d9\u30fc\u30b8\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u306b\u5f71\u97ff\u3092\u4e0e\u3048\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3092\u6700\u9069\u5316\u3059\u308b\u306b\u306f\u3001\u4ee5\u4e0b\u306e\u70b9\u306b\u6ce8\u610f\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-53\">\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:#ffb36b;color:#FFF\" class=\"sgb-box-simple__title\">\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u3092\u6700\u9069\u5316\u3059\u308b\u305f\u3081\u306e\u6ce8\u610f\u70b9<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#ffb36b;background-color:#FFF\">\n<ol class=\"wp-block-list\"><div id=\"sgb-css-id-51\">\n<li>\u4e0d\u8981\u306a\u4e2d\u9593\u6587\u5b57\u5217\u306e\u751f\u6210\u3092\u907f\u3051\u308b<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-52\">\n<li>\u5fc5\u8981\u306a\u90e8\u5206\u306e\u307f\u3092\u62bd\u51fa\u3057\u3001\u5143\u306e\u6587\u5b57\u5217\u3078\u306e\u53c2\u7167\u3092\u4fdd\u6301\u3057\u306a\u3044<\/li>\n<\/div>\n\n\n<li>\u6587\u5b57\u5217\u30d7\u30fc\u30eb\u3092\u6d3b\u7528\u3059\u308b\uff08<code>String.intern()<\/code>\u30e1\u30bd\u30c3\u30c9\uff09<\/li>\n<\/ol>\n<\/div><\/div>\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=\"\">\/\/ \u975e\u52b9\u7387\u7684\u306a\u4f7f\u7528\u4f8b\nString longString = \"This is a very long string\";\nString sub1 = longString.substring(0, 4);\nString sub2 = longString.substring(5, 7);\nString result = sub1 + \" \" + sub2;\n\n\/\/ \u6700\u9069\u5316\u3055\u308c\u305f\u4f7f\u7528\u4f8b\nString result = new StringBuilder()\n    .append(longString, 0, 4)\n    .append(' ')\n    .append(longString, 5, 7)\n    .toString();<\/pre>\n\n\n<div id=\"sgb-css-id-54\">\n<h3 class=\"wp-block-heading\" id=\"i-14\">\u5927\u91cf\u306e\u6587\u5b57\u5217\u51e6\u7406\u306b\u304a\u3051\u308b\u52b9\u7387\u7684\u306asubstring\u306e\u4f7f\u3044\u65b9<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-55\">\n<p>\u5927\u91cf\u306e\u6587\u5b57\u5217\u3092\u51e6\u7406\u3059\u308b\u5834\u5408\u3001<code>substring<\/code>\u306e\u4f7f\u7528\u65b9\u6cd5\u304c\u7279\u306b\u91cd\u8981\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-58\">\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(--sgb-main-color);color:#FFF\" class=\"sgb-box-simple__title\">\u5927\u91cf\u306e\u6587\u5b57\u5217\u3092\u51e6\u7406\u3059\u308b\u5834\u5408\u306e\u65b9\u6cd5<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:var(--sgb-main-color);background-color:#FFF\">\n<ol class=\"wp-block-list\"><div id=\"sgb-css-id-56\">\n<li>\u30eb\u30fc\u30d7\u5185\u3067\u306e<code>substring<\/code>\u4f7f\u7528\u3092\u6700\u5c0f\u9650\u306b\u6291\u3048\u308b<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-57\">\n<li>\u4e2d\u9593\u7d50\u679c\u3092\u518d\u5229\u7528\u3059\u308b<\/li>\n<\/div>\n\n\n<li>\u5fc5\u8981\u306b\u5fdc\u3058\u3066<code>StringBuilder<\/code>\u3084<code>StringBuffer<\/code>\u3092\u4f7f\u7528\u3059\u308b<\/li>\n<\/ol>\n<\/div><\/div>\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=\"\">\/\/ \u975e\u52b9\u7387\u7684\u306a\u51e6\u7406\nList&lt;String&gt; processStrings(List&lt;String&gt; inputs) {\n    List&lt;String&gt; results = new ArrayList&lt;&gt;();\n    for (String input : inputs) {\n        results.add(input.substring(0, 5) + \"processed\");\n    }\n    return results;\n}\n\n\/\/ \u6700\u9069\u5316\u3055\u308c\u305f\u51e6\u7406\nList&lt;String&gt; processStringsOptimized(List&lt;String&gt; inputs) {\n    List&lt;String&gt; results = new ArrayList&lt;&gt;();\n    StringBuilder sb = new StringBuilder(15); \/\/ \u4e88\u60f3\u3055\u308c\u308b\u6700\u5927\u9577\u3067\u521d\u671f\u5316\n    for (String input : inputs) {\n        sb.setLength(0); \/\/ StringBuilder \u3092\u30ea\u30bb\u30c3\u30c8\n        sb.append(input, 0, Math.min(input.length(), 5)).append(\"processed\");\n        results.add(sb.toString());\n    }\n    return results;\n}<\/pre>\n\n\n<div id=\"sgb-css-id-59\">\n<h3 class=\"wp-block-heading\" id=\"i-15\">StringBuilder\u3068\u306e\u4f75\u7528\u306b\u3088\u308b\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u5411\u4e0a\u30c6\u30af\u30cb\u30c3\u30af<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-60\">\n<p><code>StringBuilder<\/code>\u3092\u52b9\u679c\u7684\u306b\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001<code>substring<\/code>\u64cd\u4f5c\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u5927\u5e45\u306b\u5411\u4e0a\u3055\u305b\u308b\u3053\u3068\u304c\u3067\u304d\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\"><code>StringBuilder<\/code> \u3068\u306e\u4f75\u7528\u30c6\u30af\u30cb\u30c3\u30af<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:var(--wp--preset--color--sango-main);background-color:#FFF\">\n<ol class=\"wp-block-list\"><div id=\"sgb-css-id-61\">\n<li><code>StringBuilder<\/code>\u3092\u4f7f\u7528\u3057\u3066\u6587\u5b57\u5217\u3092\u69cb\u7bc9\u3057\u3001\u6700\u5f8c\u306b<code>toString()<\/code>\u3067\u5909\u63db<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-62\">\n<li><code>append<\/code>\u30e1\u30bd\u30c3\u30c9\u3068<code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u3092\u7d44\u307f\u5408\u308f\u305b\u3066\u4f7f\u7528<\/li>\n<\/div>\n\n\n<li><code>StringBuilder<\/code>\u306e\u521d\u671f\u5bb9\u91cf\u3092\u9069\u5207\u306b\u8a2d\u5b9a\u3059\u308b<\/li>\n<\/ol>\n<\/div><\/div>\n\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 static String optimizedStringManipulation(String input, int start, int end) {\n    StringBuilder sb = new StringBuilder(end - start + 10); \/\/ \u4e88\u60f3\u3055\u308c\u308b\u6700\u5927\u9577\u3067\u521d\u671f\u5316\n    return sb.append(input, start, end)\n             .append(\"_processed\")\n             .toString();\n}<\/pre>\n\n\n<div id=\"sgb-css-id-63\">\n<h3 class=\"wp-block-heading\" id=\"i-16\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u306e\u6ce8\u610f\u70b9\u3068\u30c8\u30ec\u30fc\u30c9\u30aa\u30d5<\/h3>\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:#ffb36b;color:#FFF\" class=\"sgb-box-simple__title\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u306e\u6ce8\u610f\u70b9<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#ffb36b;background-color:#FFF\">\n<ol class=\"wp-block-list\"><div id=\"sgb-css-id-64\">\n<li>\u53ef\u8aad\u6027\u3068\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u30d0\u30e9\u30f3\u30b9\u3092\u53d6\u308b<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-65\">\n<li>\u904e\u5ea6\u306a\u6700\u9069\u5316\u3092\u907f\u3051\u308b\uff08\u30d7\u30ec\u30de\u30c1\u30e5\u30a2\u6700\u9069\u5316\uff09<\/li>\n<\/div>\n\n\n<li>\u30d7\u30ed\u30d5\u30a1\u30a4\u30ea\u30f3\u30b0\u3092\u884c\u3044\u3001\u5b9f\u969b\u306e\u30dc\u30c8\u30eb\u30cd\u30c3\u30af\u3092\u7279\u5b9a\u3057\u3066\u304b\u3089\u6700\u9069\u5316\u3059\u308b<\/li>\n<\/ol>\n<\/div><\/div>\n\n\n<div id=\"sgb-css-id-66\">\n<p>\u6700\u9069\u5316\u3092\u884c\u3046\u969b\u306f\u3001\u4ee5\u4e0b\u306e\u30ac\u30a4\u30c9\u30e9\u30a4\u30f3\u3092\u53c2\u8003\u306b\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-69\">\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\">\u6700\u9069\u5316\u3092\u884c\u3046\u969b\u306e\u30ac\u30a4\u30c9\u30e9\u30a4\u30f3<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:var(--wp--preset--color--sango-main);background-color:#FFF\">\n<ol class=\"wp-block-list\"><div id=\"sgb-css-id-67\">\n<li>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u30dc\u30c8\u30eb\u30cd\u30c3\u30af\u3092\u7279\u5b9a\u3057\u3066\u304b\u3089\u6700\u9069\u5316\u3092\u884c\u3046<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-68\">\n<li>\u6e2c\u5b9a\u53ef\u80fd\u306a\u76ee\u6a19\u3092\u8a2d\u5b9a\u3059\u308b\uff08\u4f8b\uff1a\u51e6\u7406\u6642\u9593\u309220%\u524a\u6e1b\uff09<\/li>\n<\/div>\n\n\n<li>\u6700\u9069\u5316\u524d\u5f8c\u3067\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u30c6\u30b9\u30c8\u3092\u5b9f\u65bd\u3057\u3001\u52b9\u679c\u3092\u78ba\u8a8d\u3059\u308b<\/li>\n<\/ol>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-70\">\n<p><code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u306e\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u306f\u3001\u5927\u898f\u6a21\u306a\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3084\u9ad8\u8ca0\u8377\u306a\u74b0\u5883\u3067\u7279\u306b\u91cd\u8981\u3067\u3059\u3002\u3053\u308c\u3089\u306e\u30c6\u30af\u30cb\u30c3\u30af\u3092\u9069\u5207\u306b\u9069\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u52b9\u7387\u7684\u3067\u9ad8\u901f\u306a\u6587\u5b57\u5217\u51e6\u7406\u3092\u5b9f\u73fe\u3067\u304d\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001<code>substring<\/code>\u4f7f\u7528\u6642\u306b\u3088\u304f\u906d\u9047\u3059\u308b\u30a8\u30e9\u30fc\u3068\u305d\u306e\u5bfe\u51e6\u6cd5\u306b\u3064\u3044\u3066\u8aac\u660e\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-71\">\n<h2 class=\"wp-block-heading\" id=\"i-17\">5. \u3088\u304f\u3042\u308bsubstring\u4f7f\u7528\u6642\u306e\u30a8\u30e9\u30fc\u3068\u5bfe\u51e6\u6cd5<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-72\">\n<p><code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u5f37\u529b\u306a\u6587\u5b57\u5217\u64cd\u4f5c\u30c4\u30fc\u30eb\u3067\u3059\u304c\u3001\u9069\u5207\u306b\u4f7f\u7528\u3057\u306a\u3044\u3068\u30a8\u30e9\u30fc\u304c\u767a\u751f\u3059\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u3053\u3067\u306f\u3001\u3088\u304f\u906d\u9047\u3059\u308b\u30a8\u30e9\u30fc\u3068\u305d\u306e\u5bfe\u51e6\u6cd5\u306b\u3064\u3044\u3066\u8aac\u660e\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-73\">\n<h3 class=\"wp-block-heading\" id=\"i-18\">IndexOutOfBoundsException\u3092\u56de\u907f\u3059\u308b\u305f\u3081\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-74\">\n<p><code>IndexOutOfBoundsException<\/code>\u306f\u3001<code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u4f7f\u7528\u6642\u306b\u6700\u3082\u3088\u304f\u906d\u9047\u3059\u308b\u30a8\u30e9\u30fc\u306e\u4e00\u3064\u3067\u3059\u3002\u3053\u306e\u30a8\u30e9\u30fc\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u72b6\u6cc1\u3067\u767a\u751f\u3057\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\"><code>IndexOutOfBoundsException<\/code> \u306e\u767a\u751f\u539f\u56e0<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:var(--wp--preset--color--sango-main);background-color:#FFF\">\n<ol class=\"wp-block-list\"><div id=\"sgb-css-id-75\">\n<li>\u6587\u5b57\u5217\u306e\u9577\u3055\u3092\u8d85\u3048\u308b\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u3092\u6307\u5b9a\u3057\u305f\u5834\u5408<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-76\">\n<li>\u8ca0\u306e\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u3092\u6307\u5b9a\u3057\u305f\u5834\u5408<\/li>\n<\/div>\n\n\n<li><code>beginIndex<\/code>\u304c<code>endIndex<\/code>\u3088\u308a\u5927\u304d\u3044\u5834\u5408<\/li>\n<\/ol>\n<\/div><\/div>\n\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\";\n\/\/ str.substring(10); \/\/ IndexOutOfBoundsException\n\/\/ str.substring(-1); \/\/ IndexOutOfBoundsException\n\/\/ str.substring(3, 2); \/\/ IndexOutOfBoundsException<\/pre>\n\n\n<div id=\"sgb-css-id-77\">\n<p>\u3053\u308c\u3089\u306e\u30a8\u30e9\u30fc\u3092\u56de\u907f\u3059\u308b\u305f\u3081\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u306f\u4ee5\u4e0b\u306e\u901a\u308a\u3067\u3059\u3002<\/p>\n<\/div>\n\n\n<ol class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-78\">\n<li>\u6587\u5b57\u5217\u306e\u9577\u3055\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b<\/li>\n<\/div><\/ol>\n\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\";\nint start = 3;\nif (start &lt; str.length()) {\n    String sub = str.substring(start);\n    System.out.println(sub);\n} else {\n    System.out.println(\"Index out of bounds\");\n}<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-79\">\n<li><code>Math.min()<\/code>\u3092\u4f7f\u7528\u3057\u3066\u5b89\u5168\u306a\u30a4\u30f3\u30c7\u30c3\u30af\u30b9\u3092\u78ba\u4fdd\u3059\u308b<\/li>\n<\/div><\/ol>\n\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\";\nint start = 3;\nint end = 10;\nString sub = str.substring(start, Math.min(end, str.length()));\nSystem.out.println(sub);<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-80\">\n<li>Apache Commons Lang\u306eStringUtils\u3084Guava\u306eStrings\u30af\u30e9\u30b9\u3092\u4f7f\u7528\u3059\u308b<\/li>\n<\/div><\/ol>\n\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=\"\">\/\/ Apache Commons Lang\nString str = \"Hello\";\nString sub = StringUtils.substring(str, 3, 10);\nSystem.out.println(sub);\n\n\/\/ Guava\nString str = \"Hello\";\nString sub = Strings.nullToEmpty(str).substring(0, Math.min(3, str.length()));\nSystem.out.println(sub);<\/pre>\n\n\n<div id=\"sgb-css-id-81\">\n<h3 class=\"wp-block-heading\" id=\"i-19\">null\u6587\u5b57\u5217\u306b\u5bfe\u3059\u308bNullPointerException\u306e\u51e6\u7406\u65b9\u6cd5<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-82\">\n<p><code>null<\/code>\u6587\u5b57\u5217\u306b\u5bfe\u3057\u3066<code>substring<\/code>\u3092\u547c\u3073\u51fa\u3059\u3068<code>NullPointerException<\/code>\u304c\u767a\u751f\u3057\u307e\u3059\u3002\u3053\u308c\u3092\u9632\u3050\u306b\u306f\u4ee5\u4e0b\u306e\u65b9\u6cd5\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<\/div>\n\n\n<ol class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-83\">\n<li>null\u30c1\u30a7\u30c3\u30af\u3092\u884c\u3046<\/li>\n<\/div><\/ol>\n\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 = null;\nif (str != null &amp;&amp; str.length() &gt; 5) {\n    String sub = str.substring(0, 5);\n    System.out.println(sub);\n} else {\n    System.out.println(\"String is null or too short\");\n}<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-84\">\n<li><code>Optional&lt;String&gt;<\/code>\u3092\u4f7f\u7528\u3059\u308b\uff08Java 8\u4ee5\u964d\uff09<\/li>\n<\/div><\/ol>\n\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 = null;\nOptional&lt;String&gt; optStr = Optional.ofNullable(str);\nString sub = optStr.map(s -&gt; s.substring(0, Math.min(5, s.length())))\n                   .orElse(\"\"); \/\/ or orElseGet(() -&gt; \"default value\");\nSystem.out.println(sub);<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-85\">\n<li><code>Objects.requireNonNull()<\/code>\u3092\u4f7f\u7528\u3059\u308b<\/li>\n<\/div><\/ol>\n\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 = null;\ntry {\n    String sub = Objects.requireNonNull(str).substring(0, 5);\n    System.out.println(sub);\n} catch (NullPointerException e) {\n    System.out.println(\"String is null\");\n}<\/pre>\n\n\n<div id=\"sgb-css-id-86\">\n<h3 class=\"wp-block-heading\" id=\"i-20\">\u30a8\u30e9\u30fc\u9632\u6b62\u306e\u305f\u3081\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-90\">\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\">\u30a8\u30e9\u30fc\u9632\u6b62\u306e\u305f\u3081\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:var(--wp--preset--color--sango-main);background-color:#FFF\">\n<ol class=\"wp-block-list\"><div id=\"sgb-css-id-87\">\n<li>\u5165\u529b\u5024\u306e\u30d0\u30ea\u30c7\u30fc\u30b7\u30e7\u30f3\u3092\u884c\u3046<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-88\">\n<li>\u9632\u5fa1\u7684\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u3092\u5fc3\u304c\u3051\u308b<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-89\">\n<li>\u9069\u5207\u306a\u4f8b\u5916\u51e6\u7406\u3092\u5b9f\u88c5\u3059\u308b<\/li>\n<\/div>\n\n\n<li>\u30e6\u30cb\u30c3\u30c8\u30c6\u30b9\u30c8\u3092\u4f5c\u6210\u3057\u3001\u30a8\u30c3\u30b8\u30b1\u30fc\u30b9\u3092\u30ab\u30d0\u30fc\u3059\u308b<\/li>\n<\/ol>\n<\/div><\/div>\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 static String safeSubstring(String str, int start, int end) {\n    if (str == null) {\n        return \"\";\n    }\n    int length = str.length();\n    if (start &lt; 0) start = 0;\n    if (end &gt; length) end = length;\n    if (start &gt; end) start = end;\n    return str.substring(start, end);\n}<\/pre>\n\n\n<div id=\"sgb-css-id-91\">\n<p>\u3053\u306e\u3088\u3046\u306a\u5b89\u5168\u306a<code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u3092\u4f5c\u6210\u3059\u308b\u3053\u3068\u3067\u3001\u591a\u304f\u306e\u4e00\u822c\u7684\u306a\u30a8\u30e9\u30fc\u3092\u9632\u3050\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-92\">\n<p>\u30c7\u30d0\u30c3\u30b0\u6642\u306b\u306f\u3001IDE\u306e\u30c7\u30d0\u30c3\u30ac\u30fc\u3092\u6d3b\u7528\u3057\u305f\u308a\u3001\u9069\u5207\u306a\u30ed\u30b0\u51fa\u529b\u3092\u884c\u3046\u3053\u3068\u3067\u3001\u30a8\u30e9\u30fc\u306e\u539f\u56e0\u3092\u7279\u5b9a\u3057\u3084\u3059\u304f\u306a\u308a\u307e\u3059\u3002\u307e\u305f\u3001\u30b3\u30fc\u30c9\u30ec\u30d3\u30e5\u30fc\u3092\u5b9f\u65bd\u3059\u308b\u3053\u3068\u3067\u3001\u6f5c\u5728\u7684\u306a\u554f\u984c\u3092\u65e9\u671f\u306b\u767a\u898b\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-93\">\n<p>\u3053\u308c\u3089\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3068\u30a8\u30e9\u30fc\u51e6\u7406\u30c6\u30af\u30cb\u30c3\u30af\u3092\u9069\u7528\u3059\u308b\u3053\u3068\u3067\u3001<code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u3092\u3088\u308a\u5b89\u5168\u306b\u3001\u305d\u3057\u3066\u52b9\u679c\u7684\u306b\u4f7f\u7528\u3059\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001<code>substring<\/code>\u3068\u95a2\u9023\u3059\u308bJava\u306e\u6587\u5b57\u5217\u64cd\u4f5c\u30e1\u30bd\u30c3\u30c9\u306b\u3064\u3044\u3066\u898b\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-94\">\n<h2 class=\"wp-block-heading\" id=\"i-21\">6. substring\u3068\u95a2\u9023\u3059\u308bJava\u306e\u6587\u5b57\u5217\u64cd\u4f5c\u30e1\u30bd\u30c3\u30c9<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-95\">\n<p><code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u5f37\u529b\u3067\u3059\u304c\u3001\u4ed6\u306e\u6587\u5b57\u5217\u64cd\u4f5c\u30e1\u30bd\u30c3\u30c9\u3068\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u3055\u3089\u306b\u67d4\u8edf\u3067\u52b9\u679c\u7684\u306a\u6587\u5b57\u5217\u51e6\u7406\u304c\u53ef\u80fd\u306b\u306a\u308a\u307e\u3059\u3002\u3053\u3053\u3067\u306f\u3001<code>substring<\/code>\u3068\u95a2\u9023\u3059\u308b\u4e3b\u8981\u306a\u30e1\u30bd\u30c3\u30c9\u3068\u305d\u306e\u4f7f\u7528\u65b9\u6cd5\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-96\">\n<h3 class=\"wp-block-heading\" id=\"i-22\">indexOf()\u3068lastIndexOf()\u3092\u4f7f\u3063\u305f\u52d5\u7684\u306asubstring\u64cd\u4f5c<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-97\">\n<p><code>indexOf()<\/code>\u3068<code>lastIndexOf()<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u6587\u5b57\u5217\u5185\u306e\u7279\u5b9a\u306e\u90e8\u5206\u6587\u5b57\u5217\u306e\u4f4d\u7f6e\u3092\u898b\u3064\u3051\u308b\u306e\u306b\u5f79\u7acb\u3061\u307e\u3059\u3002\u3053\u308c\u3089\u3092<code>substring<\/code>\u3068\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u52d5\u7684\u306a\u6587\u5b57\u5217\u62bd\u51fa\u304c\u53ef\u80fd\u306b\u306a\u308a\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 email = \"user@example.com\";\nint atIndex = email.indexOf(\"@\");\nString domain = email.substring(atIndex + 1);\nSystem.out.println(\"Domain: \" + domain);  \/\/ \u51fa\u529b: Domain: example.com\n\nString filename = \"document.txt.bak\";\nint lastDotIndex = filename.lastIndexOf(\".\");\nString extension = filename.substring(lastDotIndex + 1);\nSystem.out.println(\"File extension: \" + extension);  \/\/ \u51fa\u529b: File extension: bak<\/pre>\n\n\n<div id=\"sgb-css-id-98\">\n<p>\u3053\u308c\u3089\u306e\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u6587\u5b57\u5217\u304c\u898b\u3064\u304b\u3089\u306a\u3044\u5834\u5408\u306f-1\u3092\u8fd4\u3059\u306e\u3067\u3001\u30a8\u30e9\u30fc\u51e6\u7406\u3092\u5fd8\u308c\u305a\u306b\u884c\u3044\u307e\u3057\u3087\u3046\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 text = \"Hello, World!\";\nint commaIndex = text.indexOf(\",\");\nif (commaIndex != -1) {\n    String beforeComma = text.substring(0, commaIndex);\n    String afterComma = text.substring(commaIndex + 1).trim();\n    System.out.println(\"Before comma: \" + beforeComma);  \/\/ \u51fa\u529b: Before comma: Hello\n    System.out.println(\"After comma: \" + afterComma);    \/\/ \u51fa\u529b: After comma: World!\n} else {\n    System.out.println(\"Comma not found in the text.\");\n}<\/pre>\n\n\n<div id=\"sgb-css-id-99\">\n<p>\u3053\u308c\u3089\u306e\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u6587\u5b57\u5217\u306e\u6b63\u898f\u5316\u3084\u6a19\u6e96\u5316\u306b\u975e\u5e38\u306b\u6709\u7528\u3067\u3059\u3002<code>substring<\/code>\u3068\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u7cbe\u5bc6\u306a\u6587\u5b57\u5217\u51e6\u7406\u304c\u53ef\u80fd\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-100\">\n<h3 class=\"wp-block-heading\" id=\"i-23\">trim()\u3001toLowerCase()\u3001toUpperCase()\u3068\u306e\u7d44\u307f\u5408\u308f\u305b\u6d3b\u7528\u6cd5<\/h3>\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 userInput = \"   John Doe   \";\nString normalizedName = userInput.trim().toLowerCase();\nString firstName = normalizedName.substring(0, normalizedName.indexOf(\" \"));\nString lastName = normalizedName.substring(normalizedName.indexOf(\" \") + 1);\n\nSystem.out.println(\"First name: \" + firstName);  \/\/ \u51fa\u529b: First name: john\nSystem.out.println(\"Last name: \" + lastName);    \/\/ \u51fa\u529b: Last name: doe\n\nString url = \"HTTPS:\/\/WWW.EXAMPLE.COM\/PATH\";\nString lowercaseUrl = url.toLowerCase();\nString protocol = lowercaseUrl.substring(0, lowercaseUrl.indexOf(\":\"));\nString domain = lowercaseUrl.substring(lowercaseUrl.indexOf(\":\/\/\") + 3, lowercaseUrl.indexOf(\"\/\", lowercaseUrl.indexOf(\":\/\/\") + 3));\n\nSystem.out.println(\"Protocol: \" + protocol);  \/\/ \u51fa\u529b: Protocol: https\nSystem.out.println(\"Domain: \" + domain);      \/\/ \u51fa\u529b: Domain: www.example.com<\/pre>\n\n\n<div id=\"sgb-css-id-101\">\n<p>\u3053\u308c\u3089\u306e\u30e1\u30bd\u30c3\u30c9\u3092\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u30e6\u30fc\u30b6\u30fc\u5165\u529b\u306e\u6b63\u898f\u5316\u3084\u3001URL\u89e3\u6790\u306a\u3069\u306e\u4e00\u822c\u7684\u306a\u30bf\u30b9\u30af\u3092\u52b9\u7387\u7684\u306b\u51e6\u7406\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-102\">\n<p>\u6ce8\u610f\u70b9\u3068\u3057\u3066\u3001\u3053\u308c\u3089\u306e\u30e1\u30bd\u30c3\u30c9\u306f\u65b0\u3057\u3044\u6587\u5b57\u5217\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u8fd4\u3059\u305f\u3081\u3001\u983b\u7e41\u306a\u4f7f\u7528\u306f\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u306b\u5f71\u97ff\u3092\u4e0e\u3048\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002\u5927\u91cf\u306e\u30c7\u30fc\u30bf\u3092\u51e6\u7406\u3059\u308b\u5834\u5408\u306f\u3001<code>StringBuilder<\/code>\u3092\u4f7f\u7528\u3059\u308b\u306a\u3069\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306b\u914d\u616e\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-103\">\n<p>\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3053\u308c\u307e\u3067\u5b66\u3093\u3060\u5185\u5bb9\u3092\u7dcf\u62ec\u3057\u3001<code>substring<\/code>\u30de\u30b9\u30bf\u30fc\u3078\u306e\u9053\u306e\u308a\u3092\u307e\u3068\u3081\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-104\">\n<h2 class=\"wp-block-heading\" id=\"i-24\">7. \u307e\u3068\u3081\uff1asubstring\u30de\u30b9\u30bf\u30fc\u3078\u306e\u9053<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-105\">\n<p>\u3053\u306e\u8a18\u4e8b\u3092\u901a\u3058\u3066\u3001Java\u306e\u6587\u5b57\u5217\u64cd\u4f5c\u306e\u8981\u3068\u306a\u308b<code>substring<\/code>\u30e1\u30bd\u30c3\u30c9\u306b\u3064\u3044\u3066\u3001\u57fa\u672c\u304b\u3089\u5fdc\u7528\u307e\u3067\u5e45\u5e83\u304f\u5b66\u3073\u307e\u3057\u305f\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-106\">\n<h3 class=\"wp-block-heading\" id=\"i-25\">\u5b66\u3093\u30605\u3064\u306e\u30c6\u30af\u30cb\u30c3\u30af\u3068\u6700\u9069\u5316\u65b9\u6cd5\u306e\u5fa9\u7fd2<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-111\">\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\">\u5b66\u3093\u3060\u3053\u3068\u306e\u307e\u3068\u3081<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:var(--wp--preset--color--sango-main);background-color:#FFF\">\n<ol class=\"wp-block-list\"><div id=\"sgb-css-id-107\">\n<li>\u6587\u5b57\u5217\u306e\u4e00\u90e8\u3092\u62bd\u51fa\u3059\u308b\uff1a\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u304b\u3089\u59cb\u307e\u308a\u3001\u69d8\u3005\u306a\u72b6\u6cc1\u3067\u306e\u5fdc\u7528\u3092\u5b66\u3073\u307e\u3057\u305f\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-108\">\n<li>\u6587\u5b57\u5217\u306e\u672b\u5c3e\u3092\u53d6\u5f97\u3059\u308b\uff1a\u52d5\u7684\u306a\u9577\u3055\u306e\u6587\u5b57\u5217\u3092\u6271\u3046\u65b9\u6cd5\u3092\u7fd2\u5f97\u3057\u307e\u3057\u305f\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-109\">\n<li>\u7279\u5b9a\u306e\u30d1\u30bf\u30fc\u30f3\u306b\u57fa\u3065\u3044\u3066\u6587\u5b57\u5217\u3092\u5206\u5272\u3059\u308b\uff1a\u3088\u308a\u8907\u96d1\u306a\u6587\u5b57\u5217\u64cd\u4f5c\u306e\u57fa\u790e\u3092\u5b66\u3073\u307e\u3057\u305f\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-110\">\n<li>\u6587\u5b57\u5217\u306e\u7f6e\u63db\u3068\u7d44\u307f\u5408\u308f\u305b\u3066\u4f7f\u7528\u3059\u308b\uff1a<code>substring<\/code>\u3068\u4ed6\u306e\u30e1\u30bd\u30c3\u30c9\u306e\u7d44\u307f\u5408\u308f\u305b\u306e\u5a01\u529b\u3092\u7406\u89e3\u3057\u307e\u3057\u305f\u3002<\/li>\n<\/div>\n\n\n<li>\u6b63\u898f\u8868\u73fe\u3068\u4f75\u7528\u3057\u3066\u3088\u308a\u8907\u96d1\u306a\u62bd\u51fa\u3092\u884c\u3046\uff1a\u9ad8\u5ea6\u306a\u6587\u5b57\u5217\u51e6\u7406\u306e\u53ef\u80fd\u6027\u3092\u63a2\u308a\u307e\u3057\u305f\u3002<\/li>\n<\/ol>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-112\">\n<p>\u3055\u3089\u306b\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u306e\u30c6\u30af\u30cb\u30c3\u30af\u3001\u30a8\u30e9\u30fc\u51e6\u7406\u306e\u65b9\u6cd5\u3001\u305d\u3057\u3066\u95a2\u9023\u3059\u308b\u6587\u5b57\u5217\u64cd\u4f5c\u30e1\u30bd\u30c3\u30c9\u3068\u306e\u9023\u643a\u306b\u3064\u3044\u3066\u3082\u6df1\u304f\u6398\u308a\u4e0b\u3052\u307e\u3057\u305f\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-113\">\n<h3 class=\"wp-block-heading\" id=\"i-26\">\u3055\u3089\u306a\u308b\u6587\u5b57\u5217\u64cd\u4f5c\u30b9\u30ad\u30eb\u5411\u4e0a\u306e\u305f\u3081\u306e\u30ea\u30bd\u30fc\u30b9\u3068\u6b21\u306e\u30b9\u30c6\u30c3\u30d7<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-114\">\n<p><code>substring<\/code>\u30de\u30b9\u30bf\u30fc\u3078\u306e\u9053\u306f\u307e\u3060\u7d9a\u304d\u307e\u3059\u3002\u4ee5\u4e0b\u306e\u30ea\u30bd\u30fc\u30b9\u3068\u6b21\u306e\u30b9\u30c6\u30c3\u30d7\u3092\u53c2\u8003\u306b\u3001\u3055\u3089\u306a\u308b\u30b9\u30ad\u30eb\u30a2\u30c3\u30d7\u3092\u76ee\u6307\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-119\">\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\">\u6b21\u306e\u30b9\u30c6\u30c3\u30d7\u3078\u5411\u3051\u3066<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:var(--wp--preset--color--sango-main);background-color:#FFF\">\n<ol class=\"wp-block-list\"><div id=\"sgb-css-id-115\">\n<li>Java\u516c\u5f0f\u30c9\u30ad\u30e5\u30e1\u30f3\u30c8\u306eString\u30af\u30e9\u30b9\u30bb\u30af\u30b7\u30e7\u30f3\u3092\u8a73\u3057\u304f\u8aad\u3080<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-116\">\n<li>\u300cEffective Java\u300dby Joshua Bloch\u3067\u3001\u3088\u308a\u9ad8\u5ea6\u306a\u6587\u5b57\u5217\u64cd\u4f5c\u30c6\u30af\u30cb\u30c3\u30af\u3092\u5b66\u3076<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-117\">\n<li>\u6b63\u898f\u8868\u73fe\u306e\u9ad8\u5ea6\u306a\u4f7f\u7528\u6cd5\u3092\u7fd2\u5f97\u3059\u308b<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-118\">\n<li>Stream\u3068\u30e9\u30e0\u30c0A\u5f0f\u3092\u4f7f\u7528\u3057\u305f\u52b9\u7387\u7684\u306a\u6587\u5b57\u5217\u51e6\u7406\u3092\u5b66\u3076<\/li>\n<\/div>\n\n\n<li>NIO.2\u3092\u4f7f\u7528\u3057\u305f\u30d5\u30a1\u30a4\u30eb\u64cd\u4f5c\u3068\u6587\u5b57\u5217\u51e6\u7406\u306e\u7d44\u307f\u5408\u308f\u305b\u3092\u63a2\u6c42\u3059\u308b<\/li>\n<\/ol>\n<\/div><\/div>\n<\/div>\n\n<div 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