{"id":350,"date":"2024-10-23T11:49:52","date_gmt":"2024-10-23T02:49:52","guid":{"rendered":"https:\/\/dexall.co.jp\/articles\/?p=350"},"modified":"2025-03-24T08:53:22","modified_gmt":"2025-03-23T23:53:22","slug":"java-optional%e3%81%ae%e5%ae%8c%e5%85%a8%e3%82%ac%e3%82%a4%e3%83%89%ef%bc%9a5%e3%81%a4%e3%81%ae%e4%bd%bf%e3%81%84%e6%96%b9%e3%81%a7%e8%a7%a3%e6%b1%ba%e3%81%99%e3%82%8bnull%e5%95%8f%e9%a1%8c","status":"publish","type":"post","link":"https:\/\/dexall.co.jp\/articles\/?p=350","title":{"rendered":"Java Optional\u306e\u5b8c\u5168\u30ac\u30a4\u30c9\uff1a5\u3064\u306e\u4f7f\u3044\u65b9\u3067\u89e3\u6c7a\u3059\u308bnull\u554f\u984c"},"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. Java Optional\u3068\u306f\uff1fNullPointerException\u3068\u306e\u6226\u3044<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-1\">Optional\u30af\u30e9\u30b9\u304c\u751f\u307e\u308c\u305f\u80cc\u666f\u3068\u76ee\u7684<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-2\">NullPointerException\u304c\u3082\u305f\u3089\u3059\u554f\u984c\u70b9<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-3\">2. Optional\u306e\u57fa\u672c\uff1a\u751f\u6210\u3068\u5024\u306e\u53d6\u308a\u51fa\u3057\u65b9<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-4\">Optional\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u4f5c\u6210\u65b9\u6cd53\u7a2e\u985e<\/a>      <\/li>      <li>        <a href=\"#i-5\">isPresent()\u3068get()\u30e1\u30bd\u30c3\u30c9\u306e\u6b63\u3057\u3044\u4f7f\u3044\u65b9<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-6\">Optional\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-7\">3. Optional\u306e\u4fbf\u5229\u30e1\u30bd\u30c3\u30c9\uff1aorElse\u7cfb\u306e\u6d3b\u7528<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-8\">orElse()\u3067\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u8a2d\u5b9a\u3059\u308b<\/a>      <\/li>      <li>        <a href=\"#i-9\">orElseGet()\u3067\u9045\u5ef6\u8a55\u4fa1\u3092\u5b9f\u73fe\u3059\u308b<\/a>      <\/li>      <li>        <a href=\"#i-10\">orElseThrow()\u3067\u4f8b\u5916\u3092\u30ab\u30b9\u30bf\u30de\u30a4\u30ba\u3059\u308b<\/a>      <\/li>      <li>        <a href=\"#i-11\">orElse\u7cfb\u30e1\u30bd\u30c3\u30c9\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3068\u6ce8\u610f\u70b9<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-12\">\u5b9f\u8df5\u7684\u306a\u30b3\u30fc\u30c9\u4f8b\uff1aorElse\u7cfb\u30e1\u30bd\u30c3\u30c9\u306e\u6d3b\u7528<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-13\">4. Optional\u3068\u30e9\u30e0\u30c0\u5f0f\u306e\u7d44\u307f\u5408\u308f\u305b\u6280<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-14\">map()\u30e1\u30bd\u30c3\u30c9\u3067\u5024\u306e\u5909\u63db\u3092\u884c\u3046<\/a>      <\/li>      <li>        <a href=\"#i-15\">flatMap()\u3067Optional\u306e\u30cd\u30b9\u30c8\u3092\u89e3\u6d88\u3059\u308b<\/a>      <\/li>      <li>        <a href=\"#i-16\">filter()\u30e1\u30bd\u30c3\u30c9\u3067\u6761\u4ef6\u4ed8\u304d\u51e6\u7406\u3092\u5b9f\u73fe\u3059\u308b<\/a>      <\/li>      <li>        <a href=\"#i-17\">\u30e1\u30bd\u30c3\u30c9\u30c1\u30a7\u30fc\u30f3\u3067\u8907\u96d1\u306a\u64cd\u4f5c\u3092\u7c21\u6f54\u306b\u8868\u73fe<\/a>      <\/li>      <li>        <a href=\"#i-18\">\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3068\u6ce8\u610f\u70b9<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-19\">\u30b9\u30c8\u30ea\u30fc\u30e0API\u3068\u306e\u9023\u643a<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-20\">5. Optional\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3068\u6ce8\u610f\u70b9<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-21\">Optional\u3092\u8fd4\u308a\u5024\u3068\u3057\u3066\u4f7f\u7528\u3059\u308b\u969b\u306e\u6307\u91dd<\/a>      <\/li>      <li>        <a href=\"#i-22\">Optional\u3092\u30e1\u30bd\u30c3\u30c9\u5f15\u6570\u3068\u3057\u3066\u4f7f\u7528\u3059\u3079\u304d\u3067\u306a\u3044\u7406\u7531<\/a>      <\/li>      <li>        <a href=\"#i-23\">Optional\u306e\u8aa4\u7528\u3084\u904e\u5270\u4f7f\u7528\u3092\u907f\u3051\u308b<\/a>      <\/li>      <li>        <a href=\"#i-24\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3068\u30c6\u30b9\u30c8\u5bb9\u6613\u6027\u306e\u8003\u616e<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-25\">Java 9\u4ee5\u964d\u306e\u65b0\u6a5f\u80fd\u306e\u6d3b\u7528<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-26\">6. \u5b9f\u8df5\u7684\u306a\u30b3\u30fc\u30c9\u4f8b\uff1aOptional\u3067\u8aad\u307f\u3084\u3059\u304f\u5b89\u5168\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-27\">\u5f93\u6765\u306enull\u30c1\u30a7\u30c3\u30af\u3068Optional\u306e\u6bd4\u8f03<\/a>      <\/li>      <li>        <a href=\"#i-30\">\u30b9\u30c8\u30ea\u30fc\u30e0API\u3068Optional\u306e\u9023\u643a\u30c6\u30af\u30cb\u30c3\u30af<\/a>      <\/li>      <li>        <a href=\"#i-31\">\u30a8\u30e9\u30fc\u30cf\u30f3\u30c9\u30ea\u30f3\u30b0\u3068Optional\u306e\u7d44\u307f\u5408\u308f\u305b<\/a>      <\/li>      <li>        <a href=\"#i-32\">\u30c6\u30b9\u30c8\u5bb9\u6613\u6027\u3092\u8003\u616e\u3057\u305fOptional\u306e\u4f7f\u7528<\/a>      <\/li>      <li>        <a href=\"#i-33\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u610f\u8b58\u3057\u305fOptional\u306e\u4f7f\u7528<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-34\">Optional\u306e\u6bb5\u968e\u7684\u5c0e\u5165\u30a2\u30d7\u30ed\u30fc\u30c1<\/a>      <\/li>    <\/ul>  <\/li>  <li class=\"last\">    <a href=\"#i-35\">7. \u307e\u3068\u3081\uff1aJava Optional\u30de\u30b9\u30bf\u30fc\u3078\u306e\u9053<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-36\">Optional\u306e5\u3064\u306e\u4e3b\u8981\u306a\u4f7f\u3044\u65b9\u306e\u5fa9\u7fd2<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-37\">Optional\u3092\u4f7f\u3044\u3053\u306a\u3059\u305f\u3081\u306e\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. Java Optional\u3068\u306f\uff1fNullPointerException\u3068\u306e\u6226\u3044<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-2\">\n<h3 class=\"wp-block-heading\" id=\"i-1\">Optional\u30af\u30e9\u30b9\u304c\u751f\u307e\u308c\u305f\u80cc\u666f\u3068\u76ee\u7684<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-3\">\n<p>Java 8\u3067\u5c0e\u5165\u3055\u308c\u305f<code>Optional<\/code>\u30af\u30e9\u30b9\u306f\u3001null\u53c2\u7167\u306e\u554f\u984c\u306b\u5bfe\u3059\u308b\u512a\u96c5\u306a\u89e3\u6c7a\u7b56\u3068\u3057\u3066\u8a2d\u8a08\u3055\u308c\u307e\u3057\u305f\u3002null\u306e\u6271\u3044\u306f\u5e38\u306bJava\u958b\u767a\u8005\u306e\u60a9\u307f\u306e\u7a2e\u3067\u3057\u305f\u304c\u3001<code>Optional<\/code>\u306f\u3053\u306e\u554f\u984c\u306b\u6b63\u9762\u304b\u3089\u53d6\u308a\u7d44\u3080\u305f\u3081\u306e\u5f37\u529b\u306a\u30c4\u30fc\u30eb\u3092\u63d0\u4f9b\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-4\">\n<p><code>Optional<\/code>\u306e\u4e3b\u306a\u76ee\u7684\u306f\u4ee5\u4e0b\u306e3\u70b9\u3067\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-8\">\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>Optional<\/code> \u306e\u4e3b\u306a\u76ee\u7684<\/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-5\">\n<li><strong>null\u5b89\u5168\u6027\u306e\u5411\u4e0a<\/strong>\uff1a null\u30c1\u30a7\u30c3\u30af\u3092\u660e\u793a\u7684\u306b\u884c\u3046\u3053\u3068\u3092\u4fc3\u9032\u3057\u3001NullPointerException\u306e\u30ea\u30b9\u30af\u3092\u8efd\u6e1b\u3059\u308b\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-6\">\n<li><strong>\u660e\u793a\u7684\u306anull\u51e6\u7406\u306e\u4fc3\u9032<\/strong>\uff1a \u5024\u304c\u5b58\u5728\u3057\u306a\u3044\u53ef\u80fd\u6027\u3092\u578b\u30b7\u30b9\u30c6\u30e0\u30ec\u30d9\u30eb\u3067\u8868\u73fe\u3057\u3001\u958b\u767a\u8005\u306b\u9069\u5207\u306a\u51e6\u7406\u3092\u4fc3\u3059\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-7\">\n<li><strong>\u30b3\u30fc\u30c9\u306e\u610f\u56f3\u306e\u660e\u78ba\u5316<\/strong>\uff1a \u30e1\u30bd\u30c3\u30c9\u306e\u623b\u308a\u5024\u304c<code>Optional<\/code>\u3067\u3042\u308b\u3053\u3068\u3067\u3001\u305d\u306e\u5024\u304c\u5b58\u5728\u3057\u306a\u3044\u53ef\u80fd\u6027\u304c\u3042\u308b\u3053\u3068\u3092\u660e\u78ba\u306b\u793a\u3059\u3002<\/li>\n<\/div><\/ol>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-9\">\n<h3 class=\"wp-block-heading\" id=\"i-2\">NullPointerException\u304c\u3082\u305f\u3089\u3059\u554f\u984c\u70b9<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-10\">\n<p>NullPointerException\uff08NPE\uff09\u306f\u3001Java\u958b\u767a\u8005\u306b\u3068\u3063\u3066\u6700\u3082\u983b\u7e41\u306b\u906d\u9047\u3059\u308b\u30a8\u30e9\u30fc\u306e\u4e00\u3064\u3067\u3059\u3002NPE\u304c\u3082\u305f\u3089\u3059\u4e3b\u306a\u554f\u984c\u70b9\u306f\u4ee5\u4e0b\u306e\u901a\u308a\u3067\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\">NullPointerException\uff08NPE\uff09\u306e\u554f\u984c\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-11\">\n<li><strong>\u4e88\u671f\u305b\u306c\u30d7\u30ed\u30b0\u30e9\u30e0\u306e\u505c\u6b62<\/strong>\uff1a NPE\u306f\u5b9f\u884c\u6642\u30a8\u30e9\u30fc\u3067\u3042\u308a\u3001\u9069\u5207\u306b\u51e6\u7406\u3055\u308c\u3066\u3044\u306a\u3044\u3068\u7a81\u7136\u306e\u30d7\u30ed\u30b0\u30e9\u30e0\u505c\u6b62\u3092\u5f15\u304d\u8d77\u3053\u3057\u307e\u3059\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-12\">\n<li><strong>\u30c7\u30d0\u30c3\u30b0\u306e\u56f0\u96e3\u3055<\/strong>\uff1a NPE\u306e\u539f\u56e0\u3092\u7279\u5b9a\u3059\u308b\u306e\u306f\u6642\u306b\u96e3\u3057\u304f\u3001\u958b\u767a\u52b9\u7387\u3092\u4f4e\u4e0b\u3055\u305b\u307e\u3059\u3002<\/li>\n<\/div>\n\n\n<li><strong>\u30b3\u30fc\u30c9\u306e\u53ef\u8aad\u6027\u4f4e\u4e0b<\/strong>\uff1a \u904e\u5270\u306anull\u30c1\u30a7\u30c3\u30af\u306f\u30b3\u30fc\u30c9\u3092\u8907\u96d1\u306b\u3057\u3001\u672c\u6765\u306e\u30ed\u30b8\u30c3\u30af\u3092\u898b\u3048\u306b\u304f\u304f\u3057\u307e\u3059\u3002<\/li>\n<\/ol>\n<\/div><\/div>\n\n\n<div id=\"sgb-css-id-13\">\n<p>\u4f8b\u3048\u3070\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u30b3\u30fc\u30c9\u3092\u8003\u3048\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=\"\">public String getUpperCaseUserName(User user) {\n    return user.getName().toUpperCase();\n}<\/pre>\n\n\n<div id=\"sgb-css-id-14\">\n<p>\u4e00\u898b\u30b7\u30f3\u30d7\u30eb\u306b\u898b\u3048\u308b\u3053\u306e\u30b3\u30fc\u30c9\u3067\u3059\u304c\u3001<code>user<\/code>\u304cnull\u306e\u5834\u5408\u3001\u307e\u305f\u306f<code>user.getName()<\/code>\u304cnull\u3092\u8fd4\u3059\u5834\u5408\u3001NPE\u304c\u767a\u751f\u3057\u307e\u3059\u3002\u3053\u308c\u3092\u9632\u3050\u305f\u3081\u306b\u3001\u591a\u304f\u306e\u958b\u767a\u8005\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306anull\u30c1\u30a7\u30c3\u30af\u3092\u8ffd\u52a0\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=\"\">public String getUpperCaseUserName(User user) {\n    if (user != null &amp;&amp; user.getName() != null) {\n        return user.getName().toUpperCase();\n    }\n    return \"\";  \/\/ \u307e\u305f\u306f\u9069\u5207\u306a\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\n}<\/pre>\n\n\n<div id=\"sgb-css-id-15\">\n<p>\u3053\u306e\u3088\u3046\u306anull\u30c1\u30a7\u30c3\u30af\u306f\u3001\u30b3\u30fc\u30c9\u306e\u53ef\u8aad\u6027\u3092\u4f4e\u4e0b\u3055\u305b\u3001\u672c\u6765\u306e\u30ed\u30b8\u30c3\u30af\uff08\u30e6\u30fc\u30b6\u30fc\u540d\u3092\u5927\u6587\u5b57\u306b\u5909\u63db\u3059\u308b\u3053\u3068\uff09\u3092\u898b\u3048\u306b\u304f\u304f\u3057\u3066\u3057\u307e\u3044\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-16\">\n<p><code>Optional<\/code>\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u3053\u306e\u3088\u3046\u306a\u554f\u984c\u3092\u89e3\u6c7a\u3057\u3001\u3088\u308a\u5b89\u5168\u3067\u8868\u73fe\u529b\u8c4a\u304b\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001<code>Optional<\/code>\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u3092\u5b66\u3073\u3001\u3069\u306e\u3088\u3046\u306b\u3057\u3066null\u554f\u984c\u306b\u5bfe\u51e6\u3067\u304d\u308b\u304b\u3092\u898b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-17\">\n<h2 class=\"wp-block-heading\" id=\"i-3\">2. Optional\u306e\u57fa\u672c\uff1a\u751f\u6210\u3068\u5024\u306e\u53d6\u308a\u51fa\u3057\u65b9<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-18\">\n<h3 class=\"wp-block-heading\" id=\"i-4\">Optional\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306e\u4f5c\u6210\u65b9\u6cd53\u7a2e\u985e<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-19\">\n<p><code>Optional<\/code>\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u4f5c\u6210\u3059\u308b\u306b\u306f\u3001\u4e3b\u306b3\u3064\u306e\u65b9\u6cd5\u304c\u3042\u308a\u307e\u3059\u3002\u305d\u308c\u305e\u308c\u306e\u4f7f\u7528\u65b9\u6cd5\u3068\u9069\u5207\u306a\u5834\u9762\u3092\u898b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n\n<ol class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-20\">\n<li><strong>Optional.empty()<\/strong><\/li>\n<\/div><\/ol>\n\n\n\n<ul class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-21\">\n<li>\u7a7a\u306e<code>Optional<\/code>\u3092\u751f\u6210\u3057\u307e\u3059\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-22\">\n<li>\u5024\u304c\u5b58\u5728\u3057\u306a\u3044\u3053\u3068\u3092\u8868\u73fe\u3059\u308b\u969b\u306b\u4f7f\u7528\u3057\u307e\u3059\u3002<\/li>\n<\/div><\/ul>\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=\"\">   Optional&lt;String&gt; emptyOptional = Optional.empty();<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-23\">\n<li><strong>Optional.of(value)<\/strong><\/li>\n<\/div><\/ol>\n\n\n\n<ul class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-24\">\n<li>null\u4ee5\u5916\u306e\u5024\u304b\u3089<code>Optional<\/code>\u3092\u751f\u6210\u3057\u307e\u3059\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-25\">\n<li>\u5024\u304cnull\u3067\u306a\u3044\u3053\u3068\u304c\u78ba\u5b9f\u306a\u5834\u5408\u306b\u4f7f\u7528\u3057\u307e\u3059\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-26\">\n<li>null\u3092\u6e21\u3059\u3068<code>NullPointerException<\/code>\u304c\u30b9\u30ed\u30fc\u3055\u308c\u308b\u306e\u3067\u6ce8\u610f\u304c\u5fc5\u8981\u3067\u3059\u3002<\/li>\n<\/div><\/ul>\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 name = \"John\";\n   Optional&lt;String&gt; nameOptional = Optional.of(name);<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-27\">\n<li><strong>Optional.ofNullable(value)<\/strong><\/li>\n<\/div><\/ol>\n\n\n\n<ul class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-28\">\n<li>null\u3092\u542b\u3080\u53ef\u80fd\u6027\u306e\u3042\u308b\u5024\u304b\u3089<code>Optional<\/code>\u3092\u751f\u6210\u3057\u307e\u3059\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-29\">\n<li>\u5024\u304cnull\u304b\u3082\u3057\u308c\u306a\u3044\u5834\u5408\u306b\u5b89\u5168\u306b\u4f7f\u7528\u3067\u304d\u307e\u3059\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-30\">\n<li>null\u304c\u6e21\u3055\u308c\u305f\u5834\u5408\u306f\u7a7a\u306e<code>Optional<\/code>\u3092\u8fd4\u3057\u307e\u3059\u3002<\/li>\n<\/div><\/ul>\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 nullableName = getNameFromDatabase(); \/\/ null\u306e\u53ef\u80fd\u6027\u3042\u308a\n   Optional&lt;String&gt; nameOptional = Optional.ofNullable(nullableName);<\/pre>\n\n\n<div id=\"sgb-css-id-31\">\n<h3 class=\"wp-block-heading\" id=\"i-5\">isPresent()\u3068get()\u30e1\u30bd\u30c3\u30c9\u306e\u6b63\u3057\u3044\u4f7f\u3044\u65b9<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-32\">\n<p><code>Optional<\/code>\u304b\u3089\u5024\u3092\u5b89\u5168\u306b\u53d6\u308a\u51fa\u3059\u306b\u306f\u3001<code>isPresent()<\/code>\u3068<code>get()<\/code>\u30e1\u30bd\u30c3\u30c9\u3092\u7d44\u307f\u5408\u308f\u305b\u3066\u4f7f\u7528\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-33\">\n<p>1.<strong>isPresent()\u30e1\u30bd\u30c3\u30c9<\/strong><\/p>\n<\/div>\n\n\n<ul class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-34\">\n<li><code>Optional<\/code>\u304c\u5024\u3092\u542b\u3093\u3067\u3044\u308b\u304b\u3069\u3046\u304b\u3092\u78ba\u8a8d\u3057\u307e\u3059\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-35\">\n<li>\u623b\u308a\u5024\u306f<code>boolean<\/code>\u578b\u3067\u3059\u3002<\/li>\n<\/div><\/ul>\n\n\n<div id=\"sgb-css-id-36\">\n<p>2.<strong>get()\u30e1\u30bd\u30c3\u30c9<\/strong><\/p>\n<\/div>\n\n\n<ul class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-37\">\n<li><code>Optional<\/code>\u304b\u3089\u5024\u3092\u53d6\u308a\u51fa\u3057\u307e\u3059\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-38\">\n<li>\u5024\u304c\u5b58\u5728\u3057\u306a\u3044\u5834\u5408\u306f<code>NoSuchElementException<\/code>\u3092\u30b9\u30ed\u30fc\u3057\u307e\u3059\u3002<\/li>\n<\/div><\/ul>\n\n\n<div id=\"sgb-css-id-39\">\n<p>\u4ee5\u4e0b\u306f\u3001<code>isPresent()<\/code>\u3068<code>get()<\/code>\u3092\u7d44\u307f\u5408\u308f\u305b\u305f\u5b89\u5168\u306a\u5024\u306e\u53d6\u308a\u51fa\u3057\u65b9\u306e\u4f8b\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=\"\">Optional&lt;String&gt; nameOptional = Optional.ofNullable(getNameFromDatabase());\nif (nameOptional.isPresent()) {\n    String name = nameOptional.get();\n    System.out.println(\"Name: \" + name);\n} else {\n    System.out.println(\"Name not found\");\n}<\/pre>\n\n\n<div id=\"sgb-css-id-40\">\n<p>\u3057\u304b\u3057\u3001\u3053\u306e\u65b9\u6cd5\u306f<code>Optional<\/code>\u306e\u5229\u70b9\u3092\u5341\u5206\u306b\u6d3b\u304b\u3057\u3066\u3044\u308b\u3068\u306f\u8a00\u3048\u307e\u305b\u3093\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u7d39\u4ecb\u3059\u308b<code>orElse<\/code>\u7cfb\u306e\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3059\u308b\u3068\u3001\u3088\u308a\u7c21\u6f54\u3067\u8868\u73fe\u529b\u8c4a\u304b\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-41\">\n<h3 class=\"wp-block-heading\" id=\"i-6\">Optional\u306e\u57fa\u672c\u7684\u306a\u4f7f\u3044\u65b9\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-42\">\n<p>1.null\u306e\u4ee3\u308f\u308a\u306b<code>Optional.empty()<\/code>\u3092\u8fd4\u3059<\/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 Optional&lt;User&gt; findUserById(int id) {\n       User user = userRepository.findById(id);\n       return Optional.ofNullable(user);\n   }<\/pre>\n\n\n<div id=\"sgb-css-id-43\">\n<p>2.<code>Optional<\/code>\u3092\u30e1\u30bd\u30c3\u30c9\u306e\u5f15\u6570\u3068\u3057\u3066\u4f7f\u7528\u3057\u306a\u3044<\/p>\n<\/div>\n\n\n<ul class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-44\">\n<li>\u4ee3\u308f\u308a\u306b\u3001\u30aa\u30fc\u30d0\u30fc\u30ed\u30fc\u30c9\u3055\u308c\u305f\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u3092\u691c\u8a0e\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/li>\n<\/div><\/ul>\n\n\n<div id=\"sgb-css-id-45\">\n<p>3.\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3084\u30b9\u30c8\u30ea\u30fc\u30e0\u3092<code>Optional<\/code>\u3067\u30e9\u30c3\u30d7\u3057\u306a\u3044<\/p>\n<\/div>\n\n\n<ul class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-46\">\n<li>\u7a7a\u306e\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3092\u8fd4\u3059\u65b9\u304c\u9069\u5207\u3067\u3059\u3002<\/li>\n<\/div><\/ul>\n\n\n<div id=\"sgb-css-id-47\">\n<p>4.<code>Optional&lt;Optional&lt;T&gt;&gt;<\/code>\u306e\u3088\u3046\u306a\u5165\u308c\u5b50\u69cb\u9020\u3092\u907f\u3051\u308b<\/p>\n<\/div>\n\n\n<ul class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-48\">\n<li>\u8907\u96d1\u3055\u304c\u5897\u3057\u3001\u30b3\u30fc\u30c9\u306e\u53ef\u8aad\u6027\u304c\u4f4e\u4e0b\u3057\u307e\u3059\u3002<\/li>\n<\/div><\/ul>\n\n\n<div id=\"sgb-css-id-49\">\n<p>\u3053\u308c\u3089\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3092\u5b88\u308b\u3053\u3068\u3067\u3001<code>Optional<\/code>\u3092\u52b9\u679c\u7684\u306b\u4f7f\u7528\u3057\u3001\u30b3\u30fc\u30c9\u306e\u54c1\u8cea\u3092\u5411\u4e0a\u3055\u305b\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001<code>Optional<\/code>\u306e\u3088\u308a\u9ad8\u5ea6\u306a\u4f7f\u7528\u65b9\u6cd5\u306b\u3064\u3044\u3066\u5b66\u3093\u3067\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-50\">\n<h2 class=\"wp-block-heading\" id=\"i-7\">3. Optional\u306e\u4fbf\u5229\u30e1\u30bd\u30c3\u30c9\uff1aorElse\u7cfb\u306e\u6d3b\u7528<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-51\">\n<p><code>Optional<\/code>\u30af\u30e9\u30b9\u306f\u3001\u5024\u304c\u5b58\u5728\u3057\u306a\u3044\u5834\u5408\u306e\u4ee3\u66ff\u51e6\u7406\u3092\u7c21\u6f54\u306b\u8a18\u8ff0\u3059\u308b\u305f\u3081\u306e\u4fbf\u5229\u306a\u30e1\u30bd\u30c3\u30c9\u3092\u63d0\u4f9b\u3057\u3066\u3044\u307e\u3059\u3002\u3053\u3053\u3067\u306f\u3001<code>orElse<\/code>\u7cfb\u306e\u30e1\u30bd\u30c3\u30c9\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u898b\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-52\">\n<h3 class=\"wp-block-heading\" id=\"i-8\">orElse()\u3067\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u8a2d\u5b9a\u3059\u308b<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-53\">\n<p><code>orElse()<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001<code>Optional<\/code>\u304c\u7a7a\u306e\u5834\u5408\u306b\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u8fd4\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 name = Optional.ofNullable(getUserName())\n                      .orElse(\"Guest\");<\/pre>\n\n\n<div id=\"sgb-css-id-54\">\n<p>\u3053\u306e\u30e1\u30bd\u30c3\u30c9\u306f\u7c21\u5358\u306b\u4f7f\u3048\u307e\u3059\u304c\u3001\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u304c\u5e38\u306b\u8a55\u4fa1\u3055\u308c\u308b\u305f\u3081\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306b\u5f71\u97ff\u3092\u4e0e\u3048\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-55\">\n<h3 class=\"wp-block-heading\" id=\"i-9\">orElseGet()\u3067\u9045\u5ef6\u8a55\u4fa1\u3092\u5b9f\u73fe\u3059\u308b<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-56\">\n<p><code>orElseGet()<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001<code>Optional<\/code>\u304c\u7a7a\u306e\u5834\u5408\u306b\u306e\u307f\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u751f\u6210\u3057\u307e\u3059\u3002\u3053\u308c\u306f\u3001\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u306e\u751f\u6210\u30b3\u30b9\u30c8\u304c\u9ad8\u3044\u5834\u5408\u306b\u7279\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 name = Optional.ofNullable(getUserName())\n                      .orElseGet(() -&gt; generateRandomName());<\/pre>\n\n\n<div id=\"sgb-css-id-57\">\n<p><code>orElseGet()<\/code>\u306f<code>Supplier<\/code>\u30a4\u30f3\u30bf\u30fc\u30d5\u30a7\u30fc\u30b9\u3092\u4f7f\u7528\u3059\u308b\u305f\u3081\u3001\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u306e\u751f\u6210\u3092\u9045\u5ef6\u3055\u305b\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-58\">\n<h3 class=\"wp-block-heading\" id=\"i-10\">orElseThrow()\u3067\u4f8b\u5916\u3092\u30ab\u30b9\u30bf\u30de\u30a4\u30ba\u3059\u308b<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-59\">\n<p><code>orElseThrow()<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001<code>Optional<\/code>\u304c\u7a7a\u306e\u5834\u5408\u306b\u6307\u5b9a\u3057\u305f\u4f8b\u5916\u3092\u30b9\u30ed\u30fc\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=\"\">User user = Optional.ofNullable(getUserById(id))\n                    .orElseThrow(() -&gt; new UserNotFoundException(\"User not found with id: \" + id));<\/pre>\n\n\n<div id=\"sgb-css-id-60\">\n<p>Java 10\u4ee5\u964d\u3067\u306f\u3001\u5f15\u6570\u306a\u3057\u306e<code>orElseThrow()<\/code>\u3092\u4f7f\u7528\u3057\u3066<code>NoSuchElementException<\/code>\u3092\u30b9\u30ed\u30fc\u3059\u308b\u3053\u3068\u3082\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=\"\">User user = Optional.ofNullable(getUserById(id))\n                    .orElseThrow(); \/\/ Throws NoSuchElementException<\/pre>\n\n\n<div id=\"sgb-css-id-61\">\n<h3 class=\"wp-block-heading\" id=\"i-11\">orElse\u7cfb\u30e1\u30bd\u30c3\u30c9\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3068\u6ce8\u610f\u70b9<\/h3>\n<\/div>\n\n\n<ol class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-62\">\n<li><strong>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u8003\u616e\u3059\u308b<\/strong>\uff1a <code>orElse()<\/code>\u3068<code>orElseGet()<\/code>\u3092\u9069\u5207\u306b\u4f7f\u3044\u5206\u3051\u307e\u3057\u3087\u3046\u3002<\/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=\"\">   \/\/ \u826f\u3044\u4f8b\uff1a\u8efd\u91cf\u306a\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u306b\u306forElse()\u3092\u4f7f\u7528\n   String name = optional.orElse(\"\");\n\n   \/\/ \u826f\u3044\u4f8b\uff1a\u91cd\u3044\u51e6\u7406\u306b\u306forElseGet()\u3092\u4f7f\u7528\n   String name = optional.orElseGet(() -&gt; heavyOperation());<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-63\">\n<li><strong>\u526f\u4f5c\u7528\u306b\u6ce8\u610f<\/strong>\uff1a <code>orElse()<\/code>\u5185\u3067\u526f\u4f5c\u7528\u306e\u3042\u308b\u64cd\u4f5c\u3092\u884c\u308f\u306a\u3044\u3088\u3046\u306b\u3057\u307e\u3057\u3087\u3046\u3002<\/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=\"\">   \/\/ \u60aa\u3044\u4f8b\uff1aorElse()\u5185\u3067\u526f\u4f5c\u7528\u306e\u3042\u308b\u64cd\u4f5c\n   User user = Optional.ofNullable(getUser())\n                       .orElse(createNewUser()); \/\/ createNewUser()\u306f\u5e38\u306b\u5b9f\u884c\u3055\u308c\u308b\n\n   \/\/ \u826f\u3044\u4f8b\uff1a\u526f\u4f5c\u7528\u306e\u3042\u308b\u64cd\u4f5c\u306b\u306forElseGet()\u3092\u4f7f\u7528\n   User user = Optional.ofNullable(getUser())\n                       .orElseGet(() -&gt; createNewUser());<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-64\">\n<li><strong>\u9069\u5207\u306a\u4f8b\u5916\u51e6\u7406<\/strong>\uff1a <code>orElseThrow()<\/code>\u3092\u4f7f\u7528\u3057\u3066\u3001\u660e\u78ba\u306a\u30a8\u30e9\u30fc\u30e1\u30c3\u30bb\u30fc\u30b8\u3092\u63d0\u4f9b\u3057\u307e\u3057\u3087\u3046\u3002<\/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=\"\">   User user = Optional.ofNullable(getUserById(id))\n                       .orElseThrow(() -&gt; new UserNotFoundException(\"User not found with id: \" + id));<\/pre>\n\n\n<div id=\"sgb-css-id-65\">\n<h3 class=\"wp-block-heading\" id=\"i-12\">\u5b9f\u8df5\u7684\u306a\u30b3\u30fc\u30c9\u4f8b\uff1aorElse\u7cfb\u30e1\u30bd\u30c3\u30c9\u306e\u6d3b\u7528<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-66\">\n<p>\u4ee5\u4e0b\u306f\u3001\u30e6\u30fc\u30b6\u30fc\u8a8d\u8a3c\u51e6\u7406\u3067orElse\u7cfb\u30e1\u30bd\u30c3\u30c9\u3092\u6d3b\u7528\u3059\u308b\u4f8b\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=\"\">public class AuthService {\n    public User authenticate(String username, String password) {\n        return Optional.ofNullable(userRepository.findByUsername(username))\n                       .filter(user -&gt; user.checkPassword(password))\n                       .orElseThrow(() -&gt; new AuthenticationException(\"Invalid username or password\"));\n    }\n\n    public String getUserRole(User user) {\n        return Optional.ofNullable(user.getRole())\n                       .orElse(\"GUEST\");\n    }\n\n    public List&lt;String&gt; getUserPermissions(User user) {\n        return Optional.ofNullable(user.getPermissions())\n                       .orElseGet(Collections::emptyList);\n    }\n}<\/pre>\n\n\n<div id=\"sgb-css-id-67\">\n<p>\u3053\u306e\u4f8b\u3067\u306f\u3001<code>orElseThrow()<\/code>\u3092\u4f7f\u7528\u3057\u3066\u8a8d\u8a3c\u5931\u6557\u6642\u306b\u4f8b\u5916\u3092\u30b9\u30ed\u30fc\u3057\u3001<code>orElse()<\/code>\u3067\u30c7\u30d5\u30a9\u30eb\u30c8\u306e\u30ed\u30fc\u30eb\u3092\u8a2d\u5b9a\u3057\u3001<code>orElseGet()<\/code>\u3067\u7a7a\u306e\u30ea\u30b9\u30c8\u3092\u52b9\u7387\u7684\u306b\u751f\u6210\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-68\">\n<p>orElse\u7cfb\u30e1\u30bd\u30c3\u30c9\u3092\u9069\u5207\u306b\u6d3b\u7528\u3059\u308b\u3053\u3068\u3067\u3001null\u5b89\u5168\u6027\u3092\u4fdd\u3061\u306a\u304c\u3089\u3001\u3088\u308a\u7c21\u6f54\u3067\u8868\u73fe\u529b\u8c4a\u304b\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001<code>Optional<\/code>\u3068\u30e9\u30e0\u30c0\u5f0f\u3092\u7d44\u307f\u5408\u308f\u305b\u305f\u9ad8\u5ea6\u306a\u30c6\u30af\u30cb\u30c3\u30af\u306b\u3064\u3044\u3066\u5b66\u3093\u3067\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-69\">\n<h2 class=\"wp-block-heading\" id=\"i-13\">4. Optional\u3068\u30e9\u30e0\u30c0\u5f0f\u306e\u7d44\u307f\u5408\u308f\u305b\u6280<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-70\">\n<p>Optional\u3068\u30e9\u30e0\u30c0\u5f0f\u3092\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u5ba3\u8a00\u7684\u3067\u8aad\u307f\u3084\u3059\u3044\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u3053\u306e\u7d44\u307f\u5408\u308f\u305b\u306f\u3001Java 8\u3067\u5c0e\u5165\u3055\u308c\u305f\u95a2\u6570\u578b\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u7279\u5fb4\u3092\u6700\u5927\u9650\u306b\u6d3b\u7528\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-71\">\n<h3 class=\"wp-block-heading\" id=\"i-14\">map()\u30e1\u30bd\u30c3\u30c9\u3067\u5024\u306e\u5909\u63db\u3092\u884c\u3046<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-72\">\n<p><code>map()<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001Optional\u306e\u5024\u3092\u5909\u63db\u3057\u3001\u65b0\u3057\u3044Optional\u3092\u8fd4\u3057\u307e\u3059\u3002\u3053\u308c\u306b\u3088\u308a\u3001null\u30bb\u30fc\u30d5\u306a\u65b9\u6cd5\u3067\u5024\u3092\u5909\u63db\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=\"\">Optional&lt;String&gt; nameOptional = Optional.of(\"John\");\nOptional&lt;Integer&gt; lengthOptional = nameOptional.map(String::length);\nSystem.out.println(lengthOptional.orElse(0)); \/\/ \u51fa\u529b: 4<\/pre>\n\n\n<div id=\"sgb-css-id-73\">\n<p>\u3053\u306e\u4f8b\u3067\u306f\u3001\u540d\u524d\u306e\u6587\u5b57\u5217\u3092\u305d\u306e\u9577\u3055\u306b\u5909\u63db\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-74\">\n<h3 class=\"wp-block-heading\" id=\"i-15\">flatMap()\u3067Optional\u306e\u30cd\u30b9\u30c8\u3092\u89e3\u6d88\u3059\u308b<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-75\">\n<p><code>flatMap()<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u5165\u308c\u5b50\u306b\u306a\u3063\u305fOptional\u3092\u5e73\u5766\u5316\u3059\u308b\u306e\u306b\u4f7f\u7528\u3057\u307e\u3059\u3002\u3053\u308c\u306f\u3001Optional&lt;Optional&lt;T&gt;&gt;\u306e\u3088\u3046\u306a\u69cb\u9020\u3092\u907f\u3051\u308b\u306e\u306b\u5f79\u7acb\u3061\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=\"\">Optional&lt;User&gt; userOptional = Optional.of(new User(\"John\"));\nOptional&lt;String&gt; emailOptional = userOptional.flatMap(User::getEmail);<\/pre>\n\n\n<div id=\"sgb-css-id-76\">\n<p>\u3053\u306e\u4f8b\u3067\u306f\u3001<code>User::getEmail<\/code>\u30e1\u30bd\u30c3\u30c9\u304c<code>Optional&lt;String&gt;<\/code>\u3092\u8fd4\u3059\u3068\u4eee\u5b9a\u3057\u3066\u3044\u307e\u3059\u3002<code>flatMap()<\/code>\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u7d50\u679c\u3092\u5358\u4e00\u306eOptional\u306b\u30d5\u30e9\u30c3\u30c8\u5316\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-77\">\n<h3 class=\"wp-block-heading\" id=\"i-16\">filter()\u30e1\u30bd\u30c3\u30c9\u3067\u6761\u4ef6\u4ed8\u304d\u51e6\u7406\u3092\u5b9f\u73fe\u3059\u308b<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-78\">\n<p><code>filter()<\/code>\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3059\u308b\u3068\u3001\u6761\u4ef6\u306b\u57fa\u3065\u3044\u3066Optional\u306e\u5024\u3092\u30d5\u30a3\u30eb\u30bf\u30ea\u30f3\u30b0\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=\"\">Optional&lt;Integer&gt; ageOptional = Optional.of(25);\nOptional&lt;Integer&gt; adultAgeOptional = ageOptional.filter(age -&gt; age &gt;= 18);\nSystem.out.println(adultAgeOptional.isPresent()); \/\/ \u51fa\u529b: true<\/pre>\n\n\n<div id=\"sgb-css-id-79\">\n<p>\u3053\u306e\u4f8b\u3067\u306f\u3001\u5e74\u9f62\u304c18\u6b73\u4ee5\u4e0a\u306e\u5834\u5408\u306b\u306e\u307f\u5024\u3092\u4fdd\u6301\u3059\u308bOptional\u3092\u4f5c\u6210\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-80\">\n<h3 class=\"wp-block-heading\" id=\"i-17\">\u30e1\u30bd\u30c3\u30c9\u30c1\u30a7\u30fc\u30f3\u3067\u8907\u96d1\u306a\u64cd\u4f5c\u3092\u7c21\u6f54\u306b\u8868\u73fe<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-81\">\n<p>\u3053\u308c\u3089\u306e\u30e1\u30bd\u30c3\u30c9\u3092\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u8907\u96d1\u306a\u64cd\u4f5c\u3092\u7c21\u6f54\u306b\u8868\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=\"\">Optional&lt;User&gt; userOptional = getUserById(123);\nString result = userOptional\n    .filter(user -&gt; user.getAge() &gt;= 18)\n    .flatMap(User::getEmail)\n    .map(String::toUpperCase)\n    .orElse(\"No adult user found or no email available\");<\/pre>\n\n\n<div id=\"sgb-css-id-82\">\n<p>\u3053\u306e\u4f8b\u3067\u306f\u3001\u30e6\u30fc\u30b6\u30fc\u304c18\u6b73\u4ee5\u4e0a\u3067\u3042\u308b\u3053\u3068\u3092\u78ba\u8a8d\u3057\u3001\u305d\u306e\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u3092\u53d6\u5f97\u3057\u3066\u5927\u6587\u5b57\u306b\u5909\u63db\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-83\">\n<h3 class=\"wp-block-heading\" id=\"i-18\">\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3068\u6ce8\u610f\u70b9<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-86\">\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\">\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3068\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-84\">\n<li>\u9069\u5207\u306a\u30e1\u30bd\u30c3\u30c9\u3092\u9078\u629e\u3059\u308b\uff1a<code>map()<\/code>\u3068<code>flatMap()<\/code>\u3092\u9069\u5207\u306b\u4f7f\u3044\u5206\u3051\u307e\u3057\u3087\u3046\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-85\">\n<li>\u904e\u5ea6\u306b\u8907\u96d1\u306a\u30e9\u30e0\u30c0\u5f0f\u306f\u907f\u3051\u308b\uff1a\u5fc5\u8981\u306b\u5fdc\u3058\u3066\u30e1\u30bd\u30c3\u30c9\u53c2\u7167\u3092\u4f7f\u7528\u3057\u3001\u53ef\u8aad\u6027\u3092\u4fdd\u3061\u307e\u3057\u3087\u3046\u3002<\/li>\n<\/div>\n\n\n<li>\u526f\u4f5c\u7528\u3092\u6700\u5c0f\u9650\u306b\u6291\u3048\u308b\uff1a\u30e9\u30e0\u30c0\u5f0f\u5185\u3067\u5916\u90e8\u306e\u72b6\u614b\u3092\u5909\u66f4\u3059\u308b\u3053\u3068\u306f\u907f\u3051\u307e\u3057\u3087\u3046\u3002<\/li>\n<\/ol>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-87\">\n<h3 class=\"wp-block-heading\" id=\"i-19\">\u30b9\u30c8\u30ea\u30fc\u30e0API\u3068\u306e\u9023\u643a<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-88\">\n<p>Java 9\u4ee5\u964d\u3067\u306f\u3001<code>Optional<\/code>\u306e<code>stream()<\/code>\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3057\u3066\u3001<code>Optional<\/code>\u3092<code>Stream<\/code>\u306b\u5909\u63db\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=\"\">Optional&lt;String&gt; optionalName = Optional.of(\"John\");\nStream&lt;String&gt; nameStream = optionalName.stream();\nnameStream.forEach(System.out::println); \/\/ \u51fa\u529b: John<\/pre>\n\n\n<div id=\"sgb-css-id-89\">\n<p>\u3053\u306e\u6a5f\u80fd\u306f\u3001<code>Optional<\/code>\u306e\u5024\u3092<code>Stream<\/code>\u306e\u64cd\u4f5c\u3068\u7d44\u307f\u5408\u308f\u305b\u308b\u5834\u5408\u306b\u7279\u306b\u4fbf\u5229\u3067\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-90\">\n<p>Optional\u3068\u30e9\u30e0\u30c0\u5f0f\u3092\u9069\u5207\u306b\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001null\u30c1\u30a7\u30c3\u30af\u306e\u7169\u308f\u3057\u3055\u304b\u3089\u89e3\u653e\u3055\u308c\u3001\u3088\u308a\u8868\u73fe\u529b\u8c4a\u304b\u3067\u5b89\u5168\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001Optional\u3092\u4f7f\u7528\u3059\u308b\u969b\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3068\u6ce8\u610f\u70b9\u306b\u3064\u3044\u3066\u3055\u3089\u306b\u8a73\u3057\u304f\u898b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-91\">\n<h2 class=\"wp-block-heading\" id=\"i-20\">5. Optional\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3068\u6ce8\u610f\u70b9<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-92\">\n<p>Optional\u3092\u52b9\u679c\u7684\u306b\u4f7f\u7528\u3059\u308b\u306b\u306f\u3001\u3044\u304f\u3064\u304b\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3092\u5b88\u308a\u3001\u6ce8\u610f\u70b9\u306b\u6c17\u3092\u3064\u3051\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001Optional\u3092\u9069\u5207\u306b\u4f7f\u7528\u3059\u308b\u305f\u3081\u306e\u30ac\u30a4\u30c9\u30e9\u30a4\u30f3\u3092\u63d0\u4f9b\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-93\">\n<h3 class=\"wp-block-heading\" id=\"i-21\">Optional\u3092\u8fd4\u308a\u5024\u3068\u3057\u3066\u4f7f\u7528\u3059\u308b\u969b\u306e\u6307\u91dd<\/h3>\n<\/div>\n\n\n<ol class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-94\">\n<li><strong>null\u306e\u4ee3\u308f\u308a\u306bOptional.empty()\u3092\u8fd4\u3059<\/strong><\/li>\n<\/div><\/ol>\n\n\n<div id=\"sgb-css-id-95\">\n<p> \u826f\u3044\u4f8b\uff1a<\/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 Optional&lt;User&gt; findUserById(int id) {\n       User user = userRepository.findById(id);\n       return Optional.ofNullable(user);\n   }<\/pre>\n\n\n<div id=\"sgb-css-id-96\">\n<p> \u60aa\u3044\u4f8b\uff1a<\/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 Optional&lt;User&gt; findUserById(int id) {\n       User user = userRepository.findById(id);\n       return user != null ? Optional.of(user) : null; \/\/ Optional\u306bnull\u3092\u8fd4\u3059\u3079\u304d\u3067\u306f\u306a\u3044\n   }<\/pre>\n\n\n<div id=\"sgb-css-id-98\">\n<ol start=\"2\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-97\">\n<li><strong>\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3092Optional\u3067\u30e9\u30c3\u30d7\u3057\u306a\u3044<\/strong>  <\/li>\n<\/div><\/ol>\n<\/div>\n\n<div id=\"sgb-css-id-99\">\n<p> \u826f\u3044\u4f8b\uff1a\u4ee3\u308f\u308a\u306b\u7a7a\u306e\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3092\u8fd4\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=\"\">   public List&lt;User&gt; getUsers() {\n       List&lt;User&gt; users = userRepository.findAll();\n       return users != null ? users : Collections.emptyList();\n   }<\/pre>\n\n\n<div id=\"sgb-css-id-100\">\n<p> \u60aa\u3044\u4f8b\uff1a<\/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 Optional&lt;List&lt;User&gt;&gt; getUsers() {\n       List&lt;User&gt; users = userRepository.findAll();\n       return Optional.ofNullable(users);\n   }<\/pre>\n\n\n<div id=\"sgb-css-id-101\">\n<h3 class=\"wp-block-heading\" id=\"i-22\">Optional\u3092\u30e1\u30bd\u30c3\u30c9\u5f15\u6570\u3068\u3057\u3066\u4f7f\u7528\u3059\u3079\u304d\u3067\u306a\u3044\u7406\u7531<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-102\">\n<p>Optional\u3092\u30e1\u30bd\u30c3\u30c9\u306e\u5f15\u6570\u3068\u3057\u3066\u4f7f\u7528\u3059\u308b\u3053\u3068\u306f\u63a8\u5968\u3055\u308c\u307e\u305b\u3093\u3002\u305d\u306e\u4ee3\u308f\u308a\u306b\u3001\u30aa\u30fc\u30d0\u30fc\u30ed\u30fc\u30c9\u3055\u308c\u305f\u30e1\u30bd\u30c3\u30c9\u3084\u9069\u5207\u306a\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u306e\u4f7f\u7528\u3092\u691c\u8a0e\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-103\">\n<p> \u826f\u3044\u4f8b\uff1a<\/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 User createUser(String name, String email) {\n    \/\/ name\u3068email\u306e\u5fc5\u9808\u30c1\u30a7\u30c3\u30af\n}\n\npublic User createUser(String name) {\n    return createUser(name, null);\n}<\/pre>\n\n\n<div id=\"sgb-css-id-104\">\n<p> \u60aa\u3044\u4f8b\uff1a<\/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 User createUser(String name, Optional&lt;String&gt; email) {\n    \/\/ Optional\u3092\u5f15\u6570\u3068\u3057\u3066\u4f7f\u7528\n}<\/pre>\n\n\n<div id=\"sgb-css-id-105\">\n<h3 class=\"wp-block-heading\" id=\"i-23\">Optional\u306e\u8aa4\u7528\u3084\u904e\u5270\u4f7f\u7528\u3092\u907f\u3051\u308b<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-107\">\n<ol class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-106\">\n<li><strong>isPresent()\u3068get()\u306e\u904e\u5ea6\u306e\u4f7f\u7528\u3092\u907f\u3051\u308b<\/strong>  <\/li>\n<\/div><\/ol>\n<\/div>\n\n<div id=\"sgb-css-id-108\">\n<p> \u826f\u3044\u4f8b\uff1a\u4ee3\u308f\u308a\u306b\u3001map()\u3001flatMap()\u3001orElse()\u306a\u3069\u306e\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3057\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=\"\">   Optional&lt;String&gt; nameOptional = Optional.of(\"John\");\n   String name = nameOptional.orElse(\"Unknown\");<\/pre>\n\n\n<div id=\"sgb-css-id-109\">\n<p> \u60aa\u3044\u4f8b\uff1a<\/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=\"\">   Optional&lt;String&gt; nameOptional = Optional.of(\"John\");\n   String name = nameOptional.isPresent() ? nameOptional.get() : \"Unknown\";<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-110\">\n<li><strong>Optional\u306e\u5165\u308c\u5b50\u69cb\u9020\u3092\u907f\u3051\u308b<\/strong>  <\/li>\n<\/div><\/ol>\n\n\n<div id=\"sgb-css-id-111\">\n<p> \u4f8b\uff1aOptional&lt;Optional&lt;T&gt;&gt;\u306e\u3088\u3046\u306a\u69cb\u9020\u306f\u907f\u3051\u3001flatMap()\u3092\u4f7f\u7528\u3057\u3066\u5e73\u5766\u5316\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=\"\">   Optional&lt;Optional&lt;String&gt;&gt; nestedOptional = Optional.of(Optional.of(\"value\"));\n   Optional&lt;String&gt; flattenedOptional = nestedOptional.flatMap(o -&gt; o);<\/pre>\n\n\n<div id=\"sgb-css-id-112\">\n<h3 class=\"wp-block-heading\" id=\"i-24\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3068\u30c6\u30b9\u30c8\u5bb9\u6613\u6027\u306e\u8003\u616e<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-113\">\n<p>1.<strong>Optional\u306e\u751f\u6210\u30b3\u30b9\u30c8\u3092\u610f\u8b58\u3059\u308b<\/strong> <\/p>\n<\/div>\n\n<div id=\"sgb-css-id-114\">\n<p>   \u983b\u7e41\u306b\u547c\u3073\u51fa\u3055\u308c\u308b\u30e1\u30bd\u30c3\u30c9\u3084\u9ad8\u8ca0\u8377\u306e\u30eb\u30fc\u30d7\u5185\u3067\u306eOptional\u306e\u904e\u5270\u306a\u751f\u6210\u306f\u907f\u3051\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-115\">\n<p>2.<strong>\u30c6\u30b9\u30c8\u3067\u306eOptional\u306e\u6271\u3044<\/strong> <\/p>\n<\/div>\n\n<div id=\"sgb-css-id-116\">\n<p>   Optional\u3092\u8fd4\u3059\u30e1\u30bd\u30c3\u30c9\u306e\u30e2\u30c3\u30ad\u30f3\u30b0\u3068\u691c\u8a3c\uff1a<\/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=\"\">   when(userService.findUserById(1)).thenReturn(Optional.of(new User(\"John\")));\n   Optional&lt;User&gt; result = userService.findUserById(1);\n   assertTrue(result.isPresent());\n   assertEquals(\"John\", result.get().getName());<\/pre>\n\n\n<div id=\"sgb-css-id-117\">\n<h3 class=\"wp-block-heading\" id=\"i-25\">Java 9\u4ee5\u964d\u306e\u65b0\u6a5f\u80fd\u306e\u6d3b\u7528<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-118\">\n<p>Java 9\u4ee5\u964d\u3067\u5c0e\u5165\u3055\u308c\u305f\u65b0\u3057\u3044Optional\u306e\u30e1\u30bd\u30c3\u30c9\u3092\u6d3b\u7528\u3057\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n\n<ol class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-119\">\n<li><strong>or()\u30e1\u30bd\u30c3\u30c9<\/strong><\/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=\"\">   Optional&lt;String&gt; result = Optional.empty()\n                                     .or(() -&gt; Optional.of(\"default\"));<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-120\">\n<li><strong>ifPresentOrElse()\u30e1\u30bd\u30c3\u30c9<\/strong><\/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=\"\">   optional.ifPresentOrElse(\n       value -&gt; System.out.println(\"Value: \" + value),\n       () -&gt; System.out.println(\"Value is absent\")\n   );<\/pre>\n\n\n<div id=\"sgb-css-id-121\">\n<p>Optional\u3092\u9069\u5207\u306b\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001null\u306e\u6271\u3044\u306b\u95a2\u3059\u308b\u591a\u304f\u306e\u554f\u984c\u3092\u89e3\u6c7a\u3057\u3001\u3088\u308a\u5b89\u5168\u3067\u8868\u73fe\u529b\u8c4a\u304b\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u3057\u304b\u3057\u3001Optional\u306e\u904e\u5270\u4f7f\u7528\u3084\u8aa4\u7528\u306f\u3001\u304b\u3048\u3063\u3066\u30b3\u30fc\u30c9\u3092\u8907\u96d1\u306b\u3057\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306b\u5f71\u97ff\u3092\u4e0e\u3048\u308b\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u308c\u3089\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3068\u6ce8\u610f\u70b9\u3092\u5ff5\u982d\u306b\u7f6e\u304d\u306a\u304c\u3089\u3001\u72b6\u6cc1\u306b\u5fdc\u3058\u3066\u9069\u5207\u306bOptional\u3092\u6d3b\u7528\u3057\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-122\">\n<p>\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3053\u308c\u307e\u3067\u5b66\u3093\u3060\u5185\u5bb9\u3092\u5b9f\u8df5\u7684\u306a\u30b3\u30fc\u30c9\u4f8b\u3092\u901a\u3058\u3066\u7dcf\u5408\u7684\u306b\u898b\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-123\">\n<h2 class=\"wp-block-heading\" id=\"i-26\">6. \u5b9f\u8df5\u7684\u306a\u30b3\u30fc\u30c9\u4f8b\uff1aOptional\u3067\u8aad\u307f\u3084\u3059\u304f\u5b89\u5168\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-124\">\n<p>\u3053\u3053\u3067\u306f\u3001\u30e6\u30fc\u30b6\u30fc\u7ba1\u7406\u30b7\u30b9\u30c6\u30e0\u3092\u4f8b\u306b\u3001Optional\u3092\u4f7f\u7528\u3057\u3066\u8aad\u307f\u3084\u3059\u304f\u5b89\u5168\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u65b9\u6cd5\u3092\u898b\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-125\">\n<h3 class=\"wp-block-heading\" id=\"i-27\">\u5f93\u6765\u306enull\u30c1\u30a7\u30c3\u30af\u3068Optional\u306e\u6bd4\u8f03<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-126\">\n<p>\u307e\u305a\u3001\u30e6\u30fc\u30b6\u30fc\u306e\u30d7\u30ed\u30d5\u30a3\u30fc\u30eb\u60c5\u5831\u3092\u53d6\u5f97\u3059\u308b\u51e6\u7406\u3092\u5f93\u6765\u306enull\u30c1\u30a7\u30c3\u30af\u3067\u66f8\u3044\u305f\u5834\u5408\u3068\u3001Optional\u3092\u4f7f\u7528\u3057\u305f\u5834\u5408\u3067\u6bd4\u8f03\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-127\">\n<h4 class=\"wp-block-heading\" id=\"i-28\">\u5f93\u6765\u306enull\u30c1\u30a7\u30c3\u30af:<\/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 String getUserDisplayName(int userId) {\n    User user = userRepository.findById(userId);\n    if (user != null) {\n        String name = user.getName();\n        if (name != null &amp;&amp; !name.isEmpty()) {\n            return name;\n        } else {\n            String email = user.getEmail();\n            if (email != null) {\n                return email;\n            }\n        }\n    }\n    return \"Anonymous\";\n}<\/pre>\n\n\n<div id=\"sgb-css-id-128\">\n<h4 class=\"wp-block-heading\" id=\"i-29\">Optional\u3092\u4f7f\u7528\u3057\u305f\u5834\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=\"\">public String getUserDisplayName(int userId) {\n    return Optional.ofNullable(userRepository.findById(userId))\n            .map(User::getName)\n            .filter(name -&gt; !name.isEmpty())\n            .or(() -&gt; Optional.ofNullable(userRepository.findById(userId))\n                              .map(User::getEmail))\n            .orElse(\"Anonymous\");\n}<\/pre>\n\n\n<div id=\"sgb-css-id-129\">\n<p>Optional\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u30b3\u30fc\u30c9\u304c\u3088\u308a\u5ba3\u8a00\u7684\u306b\u306a\u308a\u3001\u30cd\u30b9\u30c8\u3055\u308c\u305f\u6761\u4ef6\u5206\u5c90\u304c\u6e1b\u5c11\u3057\u3066\u3044\u307e\u3059\u3002\u3053\u308c\u306b\u3088\u308a\u3001\u30b3\u30fc\u30c9\u306e\u53ef\u8aad\u6027\u3068\u4fdd\u5b88\u6027\u304c\u5411\u4e0a\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-130\">\n<h3 class=\"wp-block-heading\" id=\"i-30\">\u30b9\u30c8\u30ea\u30fc\u30e0API\u3068Optional\u306e\u9023\u643a\u30c6\u30af\u30cb\u30c3\u30af<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-131\">\n<p>Optional\u3068\u30b9\u30c8\u30ea\u30fc\u30e0\u3092\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u8907\u96d1\u306a\u51e6\u7406\u3082\u7c21\u6f54\u306b\u8868\u73fe\u3067\u304d\u307e\u3059\u3002\u4f8b\u3048\u3070\u3001\u7279\u5b9a\u306e\u6761\u4ef6\u3092\u6e80\u305f\u3059\u30e6\u30fc\u30b6\u30fc\u306e\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u30ea\u30b9\u30c8\u3092\u53d6\u5f97\u3059\u308b\u51e6\u7406\u3092\u8003\u3048\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=\"\">public List&lt;String&gt; getAdultUserEmails(List&lt;User&gt; users) {\n    return users.stream()\n            .filter(user -&gt; Optional.ofNullable(user.getAge())\n                                    .filter(age -&gt; age &gt;= 18)\n                                    .isPresent())\n            .map(User::getEmail)\n            .filter(Optional::isPresent)\n            .map(Optional::get)\n            .collect(Collectors.toList());\n}<\/pre>\n\n\n<div id=\"sgb-css-id-132\">\n<p>\u3053\u306e\u4f8b\u3067\u306f\u3001Optional\u3092\u4f7f\u7528\u3057\u3066\u5e74\u9f62\u306enull\u30c1\u30a7\u30c3\u30af\u3068\u6761\u4ef6\u30d5\u30a3\u30eb\u30bf\u30ea\u30f3\u30b0\u3092\u884c\u3044\u3001\u3055\u3089\u306b\u30e1\u30fc\u30eb\u30a2\u30c9\u30ec\u30b9\u306enull\u30c1\u30a7\u30c3\u30af\u3082\u884c\u3063\u3066\u3044\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-133\">\n<h3 class=\"wp-block-heading\" id=\"i-31\">\u30a8\u30e9\u30fc\u30cf\u30f3\u30c9\u30ea\u30f3\u30b0\u3068Optional\u306e\u7d44\u307f\u5408\u308f\u305b<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-134\">\n<p>Optional\u3092\u4f7f\u7528\u3057\u3066\u30a8\u30e9\u30fc\u30cf\u30f3\u30c9\u30ea\u30f3\u30b0\u3092\u6539\u5584\u3059\u308b\u3053\u3068\u3082\u3067\u304d\u307e\u3059\u3002\u4f8b\u3048\u3070\u3001\u30e6\u30fc\u30b6\u30fc\u304c\u898b\u3064\u304b\u3089\u306a\u3044\u5834\u5408\u306b\u30ab\u30b9\u30bf\u30e0\u4f8b\u5916\u3092\u30b9\u30ed\u30fc\u3059\u308b\u4f8b\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=\"\">public User getUserById(int userId) throws UserNotFoundException {\n    return Optional.ofNullable(userRepository.findById(userId))\n            .orElseThrow(() -&gt; new UserNotFoundException(\"User not found with id: \" + userId));\n}<\/pre>\n\n\n<div id=\"sgb-css-id-135\">\n<p>\u3053\u306e\u65b9\u6cd5\u3067\u306f\u3001null\u30c1\u30a7\u30c3\u30af\u3068\u30a8\u30e9\u30fc\u30cf\u30f3\u30c9\u30ea\u30f3\u30b0\u30921\u884c\u3067\u7c21\u6f54\u306b\u8868\u73fe\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-136\">\n<h3 class=\"wp-block-heading\" id=\"i-32\">\u30c6\u30b9\u30c8\u5bb9\u6613\u6027\u3092\u8003\u616e\u3057\u305fOptional\u306e\u4f7f\u7528<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-137\">\n<p>Optional\u3092\u8fd4\u3059\u30e1\u30bd\u30c3\u30c9\u306e\u30c6\u30b9\u30c8\u306f\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u66f8\u304f\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=\"\">@Test\npublic void testGetUserDisplayName() {\n    User user = new User(\"John Doe\", \"john@example.com\");\n    when(userRepository.findById(1)).thenReturn(user);\n\n    String displayName = userService.getUserDisplayName(1);\n\n    assertEquals(\"John Doe\", displayName);\n}\n\n@Test\npublic void testGetUserDisplayNameWhenNameIsEmpty() {\n    User user = new User(\"\", \"john@example.com\");\n    when(userRepository.findById(1)).thenReturn(user);\n\n    String displayName = userService.getUserDisplayName(1);\n\n    assertEquals(\"john@example.com\", displayName);\n}<\/pre>\n\n\n<div id=\"sgb-css-id-138\">\n<p>\u3053\u308c\u3089\u306e\u30c6\u30b9\u30c8\u3067\u306f\u3001Optional\u306e\u6319\u52d5\u3092\u7c21\u5358\u306b\u691c\u8a3c\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-139\">\n<h3 class=\"wp-block-heading\" id=\"i-33\">\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u610f\u8b58\u3057\u305fOptional\u306e\u4f7f\u7528<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-140\">\n<p>Optional\u3092\u4f7f\u7528\u3059\u308b\u969b\u306f\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3082\u8003\u616e\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002\u4f8b\u3048\u3070\u3001<code>orElse()<\/code>\u3068<code>orElseGet()<\/code>\u306e\u4f7f\u3044\u5206\u3051\u306f\u91cd\u8981\u3067\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-141\">\n<p><code>orElse()<\/code>\u3068<code>orElseGet()<\/code>\u306e\u9069\u5207\u306a\u4f7f\u3044\u5206\u3051\u306f\u3001\u7279\u306b\u91cd\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=\"\">public User getUser(String username) {\n    return Optional.ofNullable(userCache.get(username))\n            .orElseGet(() -&gt; userRepository.findByUsername(username));\n}<\/pre>\n\n\n<div id=\"sgb-css-id-142\">\n<p>\u3053\u306e\u4f8b\u3067\u306f\u3001<code>orElseGet()<\/code>\u3092\u4f7f\u7528\u3057\u3066\u3044\u307e\u3059\u3002\u3053\u308c\u306b\u3088\u308a\u3001\u30ad\u30e3\u30c3\u30b7\u30e5\u306b\u30e6\u30fc\u30b6\u30fc\u304c\u5b58\u5728\u3059\u308b\u5834\u5408\u306f\u3001\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u3078\u306e\u30a2\u30af\u30bb\u30b9\u3092\u56de\u907f\u3067\u304d\u307e\u3059\u3002<code>orElse()<\/code>\u3092\u4f7f\u7528\u3059\u308b\u3068\u3001\u30ad\u30e3\u30c3\u30b7\u30e5\u30d2\u30c3\u30c8\u306e\u5834\u5408\u3067\u3082\u30c7\u30fc\u30bf\u30d9\u30fc\u30b9\u30a2\u30af\u30bb\u30b9\u304c\u767a\u751f\u3057\u3066\u3057\u307e\u3044\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-143\">\n<p>\u307e\u305f\u3001\u4e0d\u5fc5\u8981\u306aOptional\u306e\u751f\u6210\u3092\u907f\u3051\u308b\u3053\u3068\u3082\u91cd\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=\"\">\/\/ \u907f\u3051\u308b\u3079\u304d\u4f8b\npublic Optional&lt;User&gt; findUser(String username) {\n    User user = userRepository.findByUsername(username);\n    return Optional.ofNullable(user);\n}\n\n\/\/ \u6539\u5584\u4f8b\npublic Optional&lt;User&gt; findUser(String username) {\n    return userRepository.findByUsername(username);\n}<\/pre>\n\n\n<div id=\"sgb-css-id-144\">\n<p>\u6539\u5584\u4f8b\u3067\u306f\u3001<code>userRepository<\/code>\u306e\u30e1\u30bd\u30c3\u30c9\u304c\u76f4\u63a5<code>Optional&lt;User&gt;<\/code>\u3092\u8fd4\u3059\u3088\u3046\u306b\u3059\u308b\u3053\u3068\u3067\u3001\u4e0d\u8981\u306aOptional\u306e\u751f\u6210\u3092\u907f\u3051\u3066\u3044\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-145\">\n<h3 class=\"wp-block-heading\" id=\"i-34\">Optional\u306e\u6bb5\u968e\u7684\u5c0e\u5165\u30a2\u30d7\u30ed\u30fc\u30c1<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-146\">\n<p>\u65e2\u5b58\u306e\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u306bOptional\u3092\u5c0e\u5165\u3059\u308b\u5834\u5408\u3001\u6bb5\u968e\u7684\u306a\u30a2\u30d7\u30ed\u30fc\u30c1\u304c\u52b9\u679c\u7684\u3067\u3059\u3002<\/p>\n<\/div>\n\n\n<ol class=\"wp-block-list is-style-sango-list-simple\">\n<li><strong>null\u3092\u8fd4\u3059\u53ef\u80fd\u6027\u306e\u3042\u308b\u30e1\u30bd\u30c3\u30c9\u306e\u7279\u5b9a<\/strong>\uff1a<br>\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u5185\u3067null\u3092\u8fd4\u3059\u53ef\u80fd\u6027\u306e\u3042\u308b\u30e1\u30bd\u30c3\u30c9\u3092\u6d17\u3044\u51fa\u3057\u307e\u3059\u3002<\/li>\n\n\n<div id=\"sgb-css-id-147\">\n<li><strong>\u623b\u308a\u5024\u306e\u578b\u3092Optional\u306b\u5909\u66f4<\/strong>\uff1a<br>\u7279\u5b9a\u3057\u305f\u30e1\u30bd\u30c3\u30c9\u306e\u623b\u308a\u5024\u306e\u578b\u3092<code>Optional&lt;T&gt;<\/code>\u306b\u5909\u66f4\u3057\u307e\u3059\u3002<\/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=\"\">   \/\/ Before\n   public User findUserById(int id) {\n       \/\/ implementation\n   }\n\n   \/\/ After\n   public Optional&lt;User&gt; findUserById(int id) {\n       \/\/ implementation\n       return Optional.ofNullable(user);\n   }<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-148\">\n<li><strong>\u547c\u3073\u51fa\u3057\u5074\u306e\u30b3\u30fc\u30c9\u306e\u66f4\u65b0<\/strong>\uff1a<br>Optional\u3092\u8fd4\u3059\u3088\u3046\u306b\u306a\u3063\u305f\u30e1\u30bd\u30c3\u30c9\u306e\u547c\u3073\u51fa\u3057\u5074\u306e\u30b3\u30fc\u30c9\u3092\u66f4\u65b0\u3057\u307e\u3059\u3002<\/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=\"\">   \/\/ Before\n   User user = userService.findUserById(id);\n   if (user != null) {\n       \/\/ use user\n   }\n\n   \/\/ After\n   userService.findUserById(id).ifPresent(user -&gt; {\n       \/\/ use user\n   });<\/pre>\n\n\n\n<ol start=\"4\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-149\">\n<li><strong>Optional\u306e\u30e1\u30bd\u30c3\u30c9\u3092\u6d3b\u7528\u3057\u305f\u30ea\u30d5\u30a1\u30af\u30bf\u30ea\u30f3\u30b0<\/strong>\uff1a<br><code>map()<\/code>, <code>flatMap()<\/code>, <code>filter()<\/code> \u306a\u3069\u306eOptional\u306e\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3057\u3066\u3001\u30b3\u30fc\u30c9\u3092\u3088\u308a\u30b7\u30f3\u30d7\u30eb\u306b\u30ea\u30d5\u30a1\u30af\u30bf\u30ea\u30f3\u30b0\u3057\u307e\u3059\u3002<\/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=\"\">   \/\/ Before\n   User user = userService.findUserById(id);\n   if (user != null &amp;&amp; user.getAge() &gt;= 18) {\n       return user.getEmail();\n   }\n   return null;\n\n   \/\/ After\n   return userService.findUserById(id)\n           .filter(user -&gt; user.getAge() &gt;= 18)\n           .map(User::getEmail)\n           .orElse(null);<\/pre>\n\n\n\n<ol start=\"5\" class=\"wp-block-list is-style-sango-list-simple\">\n<li><strong>\u30c6\u30b9\u30c8\u306e\u66f4\u65b0<\/strong>\uff1a<br>Optional\u3092\u4f7f\u7528\u3059\u308b\u3088\u3046\u306b\u5909\u66f4\u3055\u308c\u305f\u30b3\u30fc\u30c9\u306e\u30c6\u30b9\u30c8\u3092\u66f4\u65b0\u3057\u307e\u3059\u3002<\/li>\n\n\n<div id=\"sgb-css-id-150\">\n<li><strong>\u6bb5\u968e\u7684\u306a\u62e1\u5927<\/strong>\uff1a<br>\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u5168\u4f53\u306b\u5f90\u3005\u306bOptional\u306e\u4f7f\u7528\u3092\u62e1\u5927\u3057\u3066\u3044\u304d\u307e\u3059\u3002<\/li>\n<\/div><\/ol>\n\n\n<div id=\"sgb-css-id-151\">\n<p>\u3053\u306e\u30a2\u30d7\u30ed\u30fc\u30c1\u3092\u901a\u3058\u3066\u3001\u65e2\u5b58\u306e\u30b3\u30fc\u30c9\u30d9\u30fc\u30b9\u3092\u7834\u58ca\u3059\u308b\u3053\u3068\u306a\u304f\u3001\u5f90\u3005\u306bOptional\u306e\u6069\u6075\u3092\u53d7\u3051\u3089\u308c\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-152\">\n<p>Optional\u3092\u9069\u5207\u306b\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001null\u5b89\u5168\u6027\u306e\u5411\u4e0a\u3001\u30b3\u30fc\u30c9\u306e\u53ef\u8aad\u6027\u306e\u6539\u5584\u3001\u305d\u3057\u3066\u6f5c\u5728\u7684\u306a\u30d0\u30b0\u306e\u6e1b\u5c11\u304c\u671f\u5f85\u3067\u304d\u307e\u3059\u3002\u305f\u3060\u3057\u3001\u904e\u5270\u306a\u4f7f\u7528\u3084\u4e0d\u9069\u5207\u306a\u4f7f\u7528\u306f\u907f\u3051\u3001\u5e38\u306b\u30b3\u30fc\u30c9\u306e\u660e\u78ba\u3055\u3068\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u30d0\u30e9\u30f3\u30b9\u3092\u8003\u616e\u3059\u308b\u3053\u3068\u304c\u91cd\u8981\u3067\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-153\">\n<p>\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3053\u308c\u307e\u3067\u306e\u5185\u5bb9\u3092\u7dcf\u62ec\u3057\u3001Java\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306b\u304a\u3051\u308bOptional\u306e\u91cd\u8981\u6027\u3068\u5c06\u6765\u306e\u5c55\u671b\u306b\u3064\u3044\u3066\u8003\u5bdf\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-154\">\n<h2 class=\"wp-block-heading\" id=\"i-35\">7. \u307e\u3068\u3081\uff1aJava Optional\u30de\u30b9\u30bf\u30fc\u3078\u306e\u9053<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-155\">\n<h3 class=\"wp-block-heading\" id=\"i-36\">Optional\u306e5\u3064\u306e\u4e3b\u8981\u306a\u4f7f\u3044\u65b9\u306e\u5fa9\u7fd2<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-160\">\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\">Optional\u306e\u4e3b\u8981\u306a\u4f7f\u3044\u65b9<\/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-156\">\n<li>\u7a7a\u306eOptional\u306e\u751f\u6210\uff1a <code>Optional.empty()<\/code><\/li>\n<\/div>\n\n<div id=\"sgb-css-id-157\">\n<li>\u5024\u3092\u542b\u3080Optional\u306e\u751f\u6210\uff1a <code>Optional.of()<\/code>, <code>Optional.ofNullable()<\/code><\/li>\n<\/div>\n\n<div id=\"sgb-css-id-158\">\n<li>\u5024\u306e\u5b58\u5728\u78ba\u8a8d\u3068\u53d6\u5f97\uff1a <code>isPresent()<\/code>, <code>get()<\/code><\/li>\n<\/div>\n\n<div id=\"sgb-css-id-159\">\n<li>\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u306e\u63d0\u4f9b\uff1a <code>orElse()<\/code>, <code>orElseGet()<\/code>, <code>orElseThrow()<\/code><\/li>\n<\/div>\n\n\n<li>\u5024\u306e\u5909\u63db\u3068\u52a0\u5de5\uff1a <code>map()<\/code>, <code>flatMap()<\/code>, <code>filter()<\/code><\/li>\n<\/ol>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-161\">\n<p>\u3053\u308c\u3089\u306e\u30e1\u30bd\u30c3\u30c9\u3092\u9069\u5207\u306b\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001null\u3092\u6271\u3046\u969b\u306b\u5b89\u5168\u3067\u8868\u73fe\u529b\u8c4a\u304b\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-162\">\n<h3 class=\"wp-block-heading\" id=\"i-37\">Optional\u3092\u4f7f\u3044\u3053\u306a\u3059\u305f\u3081\u306e\u6b21\u306e\u30b9\u30c6\u30c3\u30d7<\/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: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-163\">\n<li><strong>Java\u516c\u5f0f\u30c9\u30ad\u30e5\u30e1\u30f3\u30c8\u306e\u7cbe\u8aad<\/strong>\uff1a Optional\u30af\u30e9\u30b9\u306e\u516c\u5f0f\u30c9\u30ad\u30e5\u30e1\u30f3\u30c8\u3092\u8a73\u7d30\u306b\u8aad\u307f\u8fbc\u307f\u3001\u5404\u30e1\u30bd\u30c3\u30c9\u306e\u6319\u52d5\u3092\u6df1\u304f\u7406\u89e3\u3057\u307e\u3057\u3087\u3046\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-164\">\n<li><strong>\u30aa\u30fc\u30d7\u30f3\u30bd\u30fc\u30b9\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u306e\u30b3\u30fc\u30c9\u95b2\u89a7<\/strong>\uff1a \u5b9f\u969b\u306e\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3067\u306eOptional\u306e\u4f7f\u7528\u4f8b\u3092\u5b66\u3076\u3053\u3068\u3067\u3001\u5b9f\u8df5\u7684\u306a\u77e5\u8b58\u3092\u5f97\u3089\u308c\u307e\u3059\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-165\">\n<li><strong>\u95a2\u9023\u3059\u308b\u8a2d\u8a08\u30d1\u30bf\u30fc\u30f3\u306e\u5b66\u7fd2<\/strong>\uff1a NullObject\u30d1\u30bf\u30fc\u30f3\u3084Monad\u30d1\u30bf\u30fc\u30f3\u306a\u3069\u3001Optional\u3068\u95a2\u9023\u3059\u308b\u8a2d\u8a08\u30d1\u30bf\u30fc\u30f3\u3092\u5b66\u3076\u3053\u3068\u3067\u3001\u3088\u308a\u6df1\u3044\u7406\u89e3\u304c\u5f97\u3089\u308c\u307e\u3059\u3002<\/li>\n<\/div>\n\n\n<li><strong>\u5b9f\u8df5\u3068\u30ec\u30d3\u30e5\u30fc<\/strong>\uff1a \u81ea\u8eab\u306e\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3067Optional\u3092\u7a4d\u6975\u7684\u306b\u4f7f\u7528\u3057\u3001\u4ed6\u306e\u958b\u767a\u8005\u304b\u3089\u306e\u30ec\u30d3\u30e5\u30fc\u3092\u53d7\u3051\u308b\u3053\u3068\u3067\u3001\u4f7f\u3044\u65b9\u3092\u6d17\u7df4\u3055\u305b\u3066\u3044\u304d\u307e\u3057\u3087\u3046\u3002<\/li>\n<\/ol>\n<\/div><\/div>\n\n\n<div id=\"sgb-css-id-166\">\n<p>Optional\u306e\u9069\u5207\u306a\u4f7f\u7528\u306f\u3001\u30b3\u30fc\u30c9\u306e\u54c1\u8cea\u5411\u4e0a\u3068\u30c1\u30fc\u30e0\u5185\u3067\u306e\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u6a19\u6e96\u306e\u78ba\u7acb\u306b\u8ca2\u732e\u3057\u307e\u3059\u3002null\u5b89\u5168\u6027\u306e\u5411\u4e0a\u3001\u53ef\u8aad\u6027\u306e\u6539\u5584\u3001\u660e\u793a\u7684\u306anull\u51e6\u7406\u306e\u4fc3\u9032\u306a\u3069\u3001\u591a\u304f\u306e\u5229\u70b9\u3092\u3082\u305f\u3089\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-167\">\n<p>\u4e00\u65b9\u3067\u3001\u904e\u5270\u4f7f\u7528\u3084\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3078\u306e\u5f71\u97ff\u306b\u306f\u6ce8\u610f\u304c\u5fc5\u8981\u3067\u3059\u3002\u9069\u6750\u9069\u6240\u3067Optional\u3092\u4f7f\u7528\u3057\u3001\u5e38\u306b\u30b3\u30fc\u30c9\u306e\u660e\u78ba\u3055\u3068\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u30d0\u30e9\u30f3\u30b9\u3092\u8003\u616e\u3059\u308b\u3053\u3068\u304c\u91cd\u8981\u3067\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-168\">\n<p>Optional\u306f\u3001\u30e2\u30c0\u30f3\u306aJava\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u91cd\u8981\u306a\u8981\u7d20\u306e\u4e00\u3064\u3067\u3059\u3002\u95a2\u6570\u578b\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306e\u6982\u5ff5\u3092\u53d6\u308a\u5165\u308c\u305f\u3053\u306e\u6a5f\u80fd\u3092\u7fd2\u5f97\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u5805\u7262\u3067\u8868\u73fe\u529b\u8c4a\u304b\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u529b\u304c\u8eab\u306b\u3064\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-169\">\n<p>Java\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306b\u304a\u3051\u308bOptional\u306e\u91cd\u8981\u6027\u306f\u4eca\u5f8c\u3082\u5897\u3057\u3066\u3044\u304f\u3067\u3057\u3087\u3046\u3002\u8a00\u8a9e\u306e\u9032\u5316\u306b\u4f34\u3063\u3066\u65b0\u6a5f\u80fd\u304c\u8ffd\u52a0\u3055\u308c\u308b\u53ef\u80fd\u6027\u3084\u3001\u3088\u308a\u5e83\u7bc4\u56f2\u306aAPI\u3067\u306e\u63a1\u7528\u304c\u671f\u5f85\u3055\u308c\u307e\u3059\u3002Optional\u3092\u30de\u30b9\u30bf\u30fc\u3059\u308b\u3053\u3068\u306f\u3001Java\u958b\u767a\u8005\u3068\u3057\u3066\u306e\u4fa1\u5024\u3092\u9ad8\u3081\u308b\u91cd\u8981\u306a\u30b9\u30c6\u30c3\u30d7\u3068\u306a\u308a\u307e\u3059\u3002<\/p>\n<\/div>\n\n\n<p><\/p>\n","protected":false},"excerpt":{"rendered":"<p>Warning: Undefined array key &#8220;is_admin&#8221; in \/home\/xs392991\/dexall.co.jp\/public_html\/articles\/wp-content\/themes\/ &#8230; <\/p>\n","protected":false},"author":1,"featured_media":3043,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2,74,66],"tags":[],"class_list":{"0":"post-350","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-java","8":"category-java-error-handling","9":"category-java-syntax"},"_links":{"self":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/350","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=350"}],"version-history":[{"count":3,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/350\/revisions"}],"predecessor-version":[{"id":504,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/350\/revisions\/504"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/media\/3043"}],"wp:attachment":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=350"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=350"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=350"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}