{"id":336,"date":"2024-10-23T11:39:54","date_gmt":"2024-10-23T02:39:54","guid":{"rendered":"https:\/\/dexall.co.jp\/articles\/?p=336"},"modified":"2025-03-24T08:53:23","modified_gmt":"2025-03-23T23:53:23","slug":"%e3%80%90%e4%bf%9d%e5%ad%98%e7%89%88%e3%80%91java%e9%96%8b%e7%99%ba%e8%80%85%e5%bf%85%e8%a6%8b%ef%bc%817%e3%81%a4%e3%81%ae%e5%8a%b9%e7%8e%87%e7%9a%84%e3%81%aanull%e3%83%81%e3%82%a7%e3%83%83%e3%82%af","status":"publish","type":"post","link":"https:\/\/dexall.co.jp\/articles\/?p=336","title":{"rendered":"\u3010\u4fdd\u5b58\u7248\u3011Java\u958b\u767a\u8005\u5fc5\u898b\uff017\u3064\u306e\u52b9\u7387\u7684\u306anull\u30c1\u30a7\u30c3\u30af\u624b\u6cd5\u3068\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9"},"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\u3067\u306enull\u30c1\u30a7\u30c3\u30af\u306e\u91cd\u8981\u6027<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-1\">NullPointerException\u304c\u3082\u305f\u3089\u3059\u5371\u967a\u6027<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-2\">\u52b9\u679c\u7684\u306anull\u30c1\u30a7\u30c3\u30af\u304c\u3082\u305f\u3089\u3059\u5229\u70b9<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-3\">2. \u57fa\u672c\u7684\u306anull\u30c1\u30a7\u30c3\u30af\u624b\u6cd5<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-4\">if\u6587\u3092\u4f7f\u7528\u3057\u305f\u4f1d\u7d71\u7684\u306anull\u30c1\u30a7\u30c3\u30af<\/a>      <\/li>      <li>        <a href=\"#i-5\">\u4e09\u9805\u6f14\u7b97\u5b50\u3092\u6d3b\u7528\u3057\u305f\u30b3\u30f3\u30d1\u30af\u30c8\u306anull\u30c1\u30a7\u30c3\u30af<\/a>      <\/li>      <li>        <a href=\"#i-6\">\u4f7f\u3044\u5206\u3051\u306e\u30ac\u30a4\u30c9\u30e9\u30a4\u30f3<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-7\">\u6f14\u7fd2\u554f\u984c<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-8\">3. Java 7\u4ee5\u964d\u3067\u5c0e\u5165\u3055\u308c\u305f\u4fbf\u5229\u306anull\u30c1\u30a7\u30c3\u30af\u30e1\u30bd\u30c3\u30c9<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-9\">Objects.isNull()\u3068Objects.nonNull()\u306e\u4f7f\u3044\u65b9<\/a>      <\/li>      <li>        <a href=\"#i-10\">Objects.requireNonNull()\u3067null\u6642\u306b\u4f8b\u5916\u3092\u30b9\u30ed\u30fc<\/a>      <\/li>      <li>        <a href=\"#i-11\">\u4f7f\u3044\u5206\u3051\u306e\u30ac\u30a4\u30c9\u30e9\u30a4\u30f3<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-12\">\u6f14\u7fd2\u554f\u984c<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-13\">4. Java 8\u3067\u9769\u65b0\uff1aOptional\u30af\u30e9\u30b9\u306e\u6d3b\u7528<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-14\">Optional.ofNullable()\u3067null\u5b89\u5168\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f<\/a>      <\/li>      <li>        <a href=\"#i-15\">orElse()\u3068orElseGet()\u306e\u4f7f\u3044\u5206\u3051<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-19\">Optional\u4f7f\u7528\u6642\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-20\">5. \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u8003\u616e\u3057\u305fnull\u30c1\u30a7\u30c3\u30af\u624b\u6cd5<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-21\">== null\u3068!= null\u306e\u52b9\u7387\u7684\u306a\u4f7f\u7528\u6cd5<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-22\">\u5927\u898f\u6a21\u51e6\u7406\u3067\u306e\u6700\u9069\u306anull\u30c1\u30a7\u30c3\u30af\u6226\u7565<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-23\">6. \u30b3\u30fc\u30c9\u54c1\u8cea\u5411\u4e0a\u306e\u305f\u3081\u306enull\u30c1\u30a7\u30c3\u30af\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-24\">@Nullable, @NonNull\u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3\u306e\u52b9\u679c\u7684\u306a\u6d3b\u7528<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-27\">\u9632\u5fa1\u7684\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u3067null\u8d77\u56e0\u306e\u30d0\u30b0\u3092\u4e88\u9632<\/a>      <\/li>    <\/ul>  <\/li>  <li>    <a href=\"#i-29\">7. \u3088\u304f\u3042\u308b\u9593\u9055\u3044\u3068\u6ce8\u610f\u70b9<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-30\">String.valueOf()\u306e\u843d\u3068\u3057\u7a74\u3068\u5bfe\u7b56<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-31\">\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3068\u30de\u30c3\u30d7\u306enull\u30c1\u30a7\u30c3\u30af\u306e\u52d8\u6240<\/a>      <\/li>    <\/ul>  <\/li>  <li class=\"last\">    <a href=\"#i-34\">8. \u307e\u3068\u3081\uff1a\u52b9\u679c\u7684\u306anull\u30c1\u30a7\u30c3\u30af\u3067\u5805\u7262\u306aJava\u30b3\u30fc\u30c9\u3092<\/a>    <ul class=\"menu_level_1\">      <li class=\"first\">        <a href=\"#i-35\">\u72b6\u6cc1\u306b\u5fdc\u3058\u305f\u9069\u5207\u306anull\u30c1\u30a7\u30c3\u30af\u624b\u6cd5\u306e\u9078\u629e<\/a>      <\/li>      <li class=\"last\">        <a href=\"#i-36\">\u7d99\u7d9a\u7684\u306a\u5b66\u7fd2\u3068\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u306e\u9069\u7528<\/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\u3067\u306enull\u30c1\u30a7\u30c3\u30af\u306e\u91cd\u8981\u6027<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-2\">\n<p>Java\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306b\u304a\u3044\u3066\u3001null\u30c1\u30a7\u30c3\u30af\u306f\u6975\u3081\u3066\u91cd\u8981\u306a\u6982\u5ff5\u3067\u3059\u3002\u9069\u5207\u306anull\u30c1\u30a7\u30c3\u30af\u3092\u884c\u3046\u3053\u3068\u3067\u3001\u30b3\u30fc\u30c9\u306e\u5b89\u5b9a\u6027\u304c\u5411\u4e0a\u3057\u3001\u4e88\u671f\u305b\u306c\u30d0\u30b0\u3092\u672a\u7136\u306b\u9632\u3050\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u672c\u8a18\u4e8b\u3067\u306f\u3001null\u30c1\u30a7\u30c3\u30af\u306e\u91cd\u8981\u6027\u3092\u7406\u89e3\u3057\u3001\u52b9\u679c\u7684\u306a\u5b9f\u88c5\u65b9\u6cd5\u3092\u5b66\u3076\u3053\u3068\u3067\u3001\u3088\u308a\u5805\u7262\u306aJava\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306e\u958b\u767a\u3092\u76ee\u6307\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-3\">\n<h3 class=\"wp-block-heading\" id=\"i-1\">NullPointerException\u304c\u3082\u305f\u3089\u3059\u5371\u967a\u6027<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-4\">\n<p>NullPointerException\uff08NPE\uff09\u306f\u3001Java\u30d7\u30ed\u30b0\u30e9\u30de\u30fc\u306b\u3068\u3063\u3066\u6700\u3082\u983b\u7e41\u306b\u906d\u9047\u3059\u308b\u4f8b\u5916\u306e\u4e00\u3064\u3067\u3059\u3002\u3053\u308c\u306f\u3001null\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u5bfe\u3057\u3066\u30e1\u30bd\u30c3\u30c9\u3092\u547c\u3073\u51fa\u3057\u305f\u308a\u3001\u30d5\u30a3\u30fc\u30eb\u30c9\u306b\u30a2\u30af\u30bb\u30b9\u3057\u3088\u3046\u3068\u3057\u305f\u6642\u306b\u767a\u751f\u3057\u307e\u3059\u3002NPE\u306e\u4e3b\u306a\u539f\u56e0\u306b\u306f\u4ee5\u4e0b\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\">NullPointerException \u306e\u4e3b\u306a\u539f\u56e0<\/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-5\">\n<li>\u521d\u671f\u5316\u3055\u308c\u3066\u3044\u306a\u3044\u5909\u6570\u306e\u4f7f\u7528<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-6\">\n<li>\u30e1\u30bd\u30c3\u30c9\u304cnull\u3092\u8fd4\u3059\u30b1\u30fc\u30b9\u306e\u8003\u616e\u6f0f\u308c<\/li>\n<\/div>\n\n\n<li>null\u30c1\u30a7\u30c3\u30af\u306e\u6b20\u5982<\/li>\n<\/ul>\n<\/div><\/div>\n\n\n<div id=\"sgb-css-id-7\">\n<p>NPE\u304c\u767a\u751f\u3059\u308b\u3068\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u6df1\u523b\u306a\u554f\u984c\u3092\u5f15\u304d\u8d77\u3053\u3059\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-11\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#f88080;color:#FFF\" class=\"sgb-box-simple__title\">\u767a\u751f\u3059\u308b\u554f\u984c<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#f88080;background-color:#FFF\">\n<ol class=\"wp-block-list\"><div id=\"sgb-css-id-8\">\n<li>\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u306e\u30af\u30e9\u30c3\u30b7\u30e5<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-9\">\n<li>\u30c7\u30fc\u30bf\u306e\u640d\u5931\u3084\u4e0d\u6574\u5408<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-10\">\n<li>\u30bb\u30ad\u30e5\u30ea\u30c6\u30a3\u30ea\u30b9\u30af\u306e\u5897\u5927<\/li>\n<\/div>\n\n\n<li>\u30e6\u30fc\u30b6\u30fc\u64cd\u4f5c\u306e\u8457\u3057\u3044\u4f4e\u4e0b<\/li>\n<\/ol>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-12\">\n<p>\u3053\u308c\u3089\u306e\u554f\u984c\u306f\u3001\u30d3\u30b8\u30cd\u30b9\u306b\u5927\u304d\u306a\u5f71\u97ff\u3092\u4e0e\u3048\u308b\u53ef\u80fd\u6027\u304c\u3042\u308b\u305f\u3081\u3001\u9069\u5207\u306anull\u30c1\u30a7\u30c3\u30af\u306f\u975e\u5e38\u306b\u91cd\u8981\u3067\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-13\">\n<h3 class=\"wp-block-heading\" id=\"i-2\">\u52b9\u679c\u7684\u306anull\u30c1\u30a7\u30c3\u30af\u304c\u3082\u305f\u3089\u3059\u5229\u70b9<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-14\">\n<p>\u4e00\u65b9\u3067\u3001\u52b9\u679c\u7684\u306anull\u30c1\u30a7\u30c3\u30af\u3092\u5b9f\u88c5\u3059\u308b\u3053\u3068\u3067\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u591a\u304f\u306e\u5229\u70b9\u304c\u5f97\u3089\u308c\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:#009EF3;color:#FFF\" class=\"sgb-box-simple__title\">null\u30c1\u30a7\u30c3\u30af\u304c\u3082\u305f\u3089\u3059\u5229\u70b9<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#009EF3;background-color:#FFF\">\n<ol class=\"wp-block-list\"><div id=\"sgb-css-id-15\">\n<li>\u30d0\u30b0\u306e\u6e1b\u5c11\u3068\u30b3\u30fc\u30c9\u306e\u4fe1\u983c\u6027\u5411\u4e0a<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-16\">\n<li>\u30c7\u30d0\u30c3\u30b0\u6642\u9593\u306e\u77ed\u7e2e<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-17\">\n<li>\u30b3\u30fc\u30c9\u306e\u53ef\u8aad\u6027\u3068\u4fdd\u5b88\u6027\u306e\u5411\u4e0a<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-18\">\n<li>\u4e88\u671f\u305b\u306c\u52d5\u4f5c\u306e\u9632\u6b62<\/li>\n<\/div>\n\n\n<li>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u6700\u9069\u5316<\/li>\n<\/ol>\n<\/div><\/div>\n\n\n<div id=\"sgb-css-id-19\">\n<p>\u3053\u308c\u3089\u306e\u5229\u70b9\u306f\u3001\u958b\u767a\u52b9\u7387\u306e\u5411\u4e0a\u3060\u3051\u3067\u306a\u304f\u3001\u9577\u671f\u7684\u306a\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u306e\u6210\u529f\u306b\u3082\u8ca2\u732e\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-20\">\n<p>\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u57fa\u672c\u7684\u306anull\u30c1\u30a7\u30c3\u30af\u624b\u6cd5\u304b\u3089\u3001Java 7\u4ee5\u964d\u3067\u5c0e\u5165\u3055\u308c\u305f\u4fbf\u5229\u306a\u30e1\u30bd\u30c3\u30c9\u3001\u305d\u3057\u3066Java 8\u3067\u9769\u65b0\u7684\u306aOptional\u30af\u30e9\u30b9\u307e\u3067\u3001\u69d8\u3005\u306anull\u30c1\u30a7\u30c3\u30af\u624b\u6cd5\u3092\u8a73\u3057\u304f\u89e3\u8aac\u3057\u3066\u3044\u304d\u307e\u3059\u3002\u3053\u308c\u3089\u306e\u6280\u8853\u3092\u7fd2\u5f97\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u5b89\u5168\u3067\u52b9\u7387\u7684\u306aJava\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u308b\u3088\u3046\u306b\u306a\u308b\u3067\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-21\">\n<h2 class=\"wp-block-heading\" id=\"i-3\">2. \u57fa\u672c\u7684\u306anull\u30c1\u30a7\u30c3\u30af\u624b\u6cd5<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-22\">\n<p>Java\u306b\u304a\u3051\u308b\u57fa\u672c\u7684\u306anull\u30c1\u30a7\u30c3\u30af\u624b\u6cd5\u306b\u306f\u3001\u4e3b\u306b2\u3064\u306e\u65b9\u6cd5\u304c\u3042\u308a\u307e\u3059\u3002if\u6587\u3092\u4f7f\u7528\u3057\u305f\u4f1d\u7d71\u7684\u306a\u65b9\u6cd5\u3068\u3001\u4e09\u9805\u6f14\u7b97\u5b50\u3092\u6d3b\u7528\u3057\u305f\u30b3\u30f3\u30d1\u30af\u30c8\u306a\u65b9\u6cd5\u3067\u3059\u3002\u3053\u308c\u3089\u306e\u624b\u6cd5\u3092\u9069\u5207\u306b\u4f7f\u3044\u5206\u3051\u308b\u3053\u3068\u3067\u3001\u52b9\u679c\u7684\u306bnull\u30c1\u30a7\u30c3\u30af\u3092\u5b9f\u88c5\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-23\">\n<h3 class=\"wp-block-heading\" id=\"i-4\">if\u6587\u3092\u4f7f\u7528\u3057\u305f\u4f1d\u7d71\u7684\u306anull\u30c1\u30a7\u30c3\u30af<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-24\">\n<p>if\u6587\u3092\u4f7f\u7528\u3057\u305fnull\u30c1\u30a7\u30c3\u30af\u306f\u3001\u6700\u3082\u4e00\u822c\u7684\u3067\u7406\u89e3\u3057\u3084\u3059\u3044\u65b9\u6cd5\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=\"\">if (object != null) {\n    \/\/ object\u304cnull\u3067\u306a\u3044\u5834\u5408\u306e\u51e6\u7406\n} else {\n    \/\/ object\u304cnull\u306e\u5834\u5408\u306e\u51e6\u7406\n}<\/pre>\n\n\n<div id=\"sgb-css-id-27\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#009EF3;color:#FFF\" class=\"sgb-box-simple__title\">\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#009EF3;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-25\">\n<li>\u8aad\u307f\u3084\u3059\u304f\u3001\u7406\u89e3\u3057\u3084\u3059\u3044<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-26\">\n<li>\u8907\u96d1\u306a\u6761\u4ef6\u5206\u5c90\u304c\u53ef\u80fd<\/li>\n<\/div>\n\n\n<li>\u30c7\u30d0\u30c3\u30b0\u304c\u5bb9\u6613<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-29\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#f88080;color:#FFF\" class=\"sgb-box-simple__title\">\u30c7\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#f88080;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-28\">\n<li>\u5197\u9577\u306b\u306a\u308b\u53ef\u80fd\u6027\u304c\u3042\u308b<\/li>\n<\/div>\n\n\n<li>\u30cd\u30b9\u30c8\u304c\u6df1\u304f\u306a\u308b\u3068\u53ef\u8aad\u6027\u304c\u4f4e\u4e0b\u3059\u308b<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-30\">\n<h3 class=\"wp-block-heading\" id=\"i-5\">\u4e09\u9805\u6f14\u7b97\u5b50\u3092\u6d3b\u7528\u3057\u305f\u30b3\u30f3\u30d1\u30af\u30c8\u306anull\u30c1\u30a7\u30c3\u30af<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-31\">\n<p>\u4e09\u9805\u6f14\u7b97\u5b50\u3092\u4f7f\u7528\u3059\u308b\u3068\u3001\u3088\u308a\u30b3\u30f3\u30d1\u30af\u30c8\u306bnull\u30c1\u30a7\u30c3\u30af\u3092\u884c\u3048\u307e\u3059\u3002<\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">String result = (str != null) ? str : \"\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\";<\/pre>\n\n\n<div id=\"sgb-css-id-34\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#009EF3;color:#FFF\" class=\"sgb-box-simple__title\">\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#009EF3;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-32\">\n<li>\u30b3\u30f3\u30d1\u30af\u30c8\u3067\u7c21\u6f54<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-33\">\n<li>1\u884c\u3067\u8a18\u8ff0\u53ef\u80fd<\/li>\n<\/div>\n\n\n<li>\u5909\u6570\u3078\u306e\u4ee3\u5165\u3068\u7d44\u307f\u5408\u308f\u305b\u3084\u3059\u3044<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-37\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#f88080;color:#FFF\" class=\"sgb-box-simple__title\">\u30c7\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#f88080;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-35\">\n<li>\u8907\u96d1\u306a\u6761\u4ef6\u3067\u306f\u8aad\u307f\u306b\u304f\u304f\u306a\u308b<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-36\">\n<li>\u591a\u91cd\u306e\u4e09\u9805\u6f14\u7b97\u5b50\u306f\u53ef\u8aad\u6027\u304c\u4f4e\u4e0b\u3059\u308b<\/li>\n<\/div>\n\n\n<li>\u30c7\u30d0\u30c3\u30b0\u304c\u96e3\u3057\u304f\u306a\u308b\u53ef\u80fd\u6027\u304c\u3042\u308b<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-38\">\n<h3 class=\"wp-block-heading\" id=\"i-6\">\u4f7f\u3044\u5206\u3051\u306e\u30ac\u30a4\u30c9\u30e9\u30a4\u30f3<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-42\">\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\u3044\u5206\u3051\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-39\">\n<li>\u5358\u7d14\u306a\u6761\u4ef6\u5206\u5c90\u306e\u5834\u5408\u306f\u4e09\u9805\u6f14\u7b97\u5b50\u3092\u4f7f\u7528<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-40\">\n<li>\u8907\u96d1\u306a\u51e6\u7406\u3084\u591a\u91cd\u306e\u6761\u4ef6\u5206\u5c90\u306b\u306fif\u6587\u3092\u4f7f\u7528<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-41\">\n<li>\u30c1\u30fc\u30e0\u306e\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u898f\u7d04\u306b\u5f93\u3046<\/li>\n<\/div>\n\n\n<li>\u53ef\u8aad\u6027\u3092\u512a\u5148\u3059\u308b<\/li>\n<\/ol>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-43\">\n<h3 class=\"wp-block-heading\" id=\"i-7\">\u6f14\u7fd2\u554f\u984c<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-44\">\n<p>\u6b21\u306e\u30b7\u30ca\u30ea\u30aa\u3067\u9069\u5207\u306anull\u30c1\u30a7\u30c3\u30af\u624b\u6cd5\u3092\u9078\u629e\u3057\u3001\u5b9f\u88c5\u3057\u3066\u307f\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-45\">\n<li>\u30e6\u30fc\u30b6\u30fc\u540d\u304c\u8a2d\u5b9a\u3055\u308c\u3066\u3044\u306a\u3044\u5834\u5408\u3001\u201dGuest\u201d\u3068\u8868\u793a\u3059\u308b<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-46\">\n<li>\u5546\u54c1\u306e\u4fa1\u683c\u304cnull\u306e\u5834\u5408\u30010\u5186\u3068\u3057\u3066\u8a08\u7b97\u3059\u308b<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-47\">\n<li>\u30ea\u30b9\u30c8\u306e\u8981\u7d20\u6570\u3092\u8fd4\u3059\u95a2\u6570\u3067\u3001\u30ea\u30b9\u30c8\u304cnull\u306e\u5834\u5408\u306f-1\u3092\u8fd4\u3059<\/li>\n<\/div><\/ol>\n\n\n<div id=\"sgb-css-id-48\">\n<p>\u3053\u308c\u3089\u306e\u57fa\u672c\u7684\u306anull\u30c1\u30a7\u30c3\u30af\u624b\u6cd5\u3092\u7fd2\u5f97\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u5b89\u5168\u3067\u8aad\u307f\u3084\u3059\u3044\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001Java 7\u4ee5\u964d\u3067\u5c0e\u5165\u3055\u308c\u305f\u4fbf\u5229\u306anull\u30c1\u30a7\u30c3\u30af\u30e1\u30bd\u30c3\u30c9\u306b\u3064\u3044\u3066\u5b66\u3093\u3067\u3044\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-49\">\n<h2 class=\"wp-block-heading\" id=\"i-8\">3. Java 7\u4ee5\u964d\u3067\u5c0e\u5165\u3055\u308c\u305f\u4fbf\u5229\u306anull\u30c1\u30a7\u30c3\u30af\u30e1\u30bd\u30c3\u30c9<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-50\">\n<p>Java 7\u4ee5\u964d\u3001<code>java.util.Objects<\/code>\u30af\u30e9\u30b9\u306b\u4fbf\u5229\u306anull\u30c1\u30a7\u30c3\u30af\u30e1\u30bd\u30c3\u30c9\u304c\u5c0e\u5165\u3055\u308c\u307e\u3057\u305f\u3002\u3053\u308c\u3089\u306e\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u7c21\u6f54\u3067\u5b89\u5168\u306anull\u30c1\u30a7\u30c3\u30af\u3092\u5b9f\u88c5\u3067\u304d\u307e\u3059\u3002\u4e3b\u306a\u30e1\u30bd\u30c3\u30c9\u306b\u306f<code>isNull()<\/code>, <code>nonNull()<\/code>, <code>requireNonNull()<\/code>\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-51\">\n<h3 class=\"wp-block-heading\" id=\"i-9\">Objects.isNull()\u3068Objects.nonNull()\u306e\u4f7f\u3044\u65b9<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-52\">\n<p>\u3053\u308c\u3089\u306e\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u304cnull\u3067\u3042\u308b\u304b\u3069\u3046\u304b\u3092\u7c21\u5358\u306b\u78ba\u8a8d\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=\"\">import java.util.Objects;\n\npublic class NullCheckExample {\n    public static void main(String[] args) {\n        String str = null;\n\n        \/\/ Objects.isNull()\u306e\u4f7f\u7528\u4f8b\n        if (Objects.isNull(str)) {\n            System.out.println(\"str\u306fnull\u3067\u3059\");\n        }\n\n        \/\/ Objects.nonNull()\u306e\u4f7f\u7528\u4f8b\n        if (Objects.nonNull(str)) {\n            System.out.println(\"str\u306fnull\u3067\u306f\u3042\u308a\u307e\u305b\u3093\");\n        }\n    }\n}<\/pre>\n\n\n<div id=\"sgb-css-id-55\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#009EF3;color:#FFF\" class=\"sgb-box-simple__title\">\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#009EF3;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-53\">\n<li>\u9759\u7684\u30e1\u30bd\u30c3\u30c9\u306a\u306e\u3067\u3001null\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u306b\u5bfe\u3057\u3066\u5b89\u5168\u306b\u547c\u3073\u51fa\u305b\u308b<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-54\">\n<li>\u30b3\u30fc\u30c9\u306e\u53ef\u8aad\u6027\u304c\u5411\u4e0a\u3059\u308b<\/li>\n<\/div>\n\n\n<li>NullPointerException\u306e\u30ea\u30b9\u30af\u304c\u4f4e\u6e1b\u3059\u308b<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-57\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#f88080;color:#FFF\" class=\"sgb-box-simple__title\">\u30c7\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#f88080;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-56\">\n<li>Java 8\u4ee5\u524d\u3067\u306f\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u304c\u82e5\u5e72\u4f4e\u4e0b\u3059\u308b\u53ef\u80fd\u6027\u304c\u3042\u308b<\/li>\n<\/div>\n\n\n<li>\u8907\u96d1\u306a\u6761\u4ef6\u5f0f\u3067\u306f\u53ef\u8aad\u6027\u304c\u4f4e\u4e0b\u3059\u308b\u5834\u5408\u304c\u3042\u308b<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-58\">\n<h3 class=\"wp-block-heading\" id=\"i-10\">Objects.requireNonNull()\u3067null\u6642\u306b\u4f8b\u5916\u3092\u30b9\u30ed\u30fc<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-59\">\n<p><code>requireNonNull()<\/code>\u30e1\u30bd\u30c3\u30c9\u306f\u3001\u5f15\u6570\u304cnull\u306e\u5834\u5408\u306b<code>NullPointerException<\/code>\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=\"\">import java.util.Objects;\n\npublic class RequireNonNullExample {\n    public static void processName(String name) {\n        \/\/ \u57fa\u672c\u7684\u306a\u4f7f\u7528\u65b9\u6cd5\n        String processedName = Objects.requireNonNull(name);\n\n        \/\/ \u30e1\u30c3\u30bb\u30fc\u30b8\u4ed8\u304d\u306e\u4f7f\u7528\u65b9\u6cd5\n        String processedName2 = Objects.requireNonNull(name, \"\u540d\u524d\u304cnull\u3067\u3059\");\n\n        \/\/ \u30b5\u30d7\u30e9\u30a4\u30e4\u30fc\u4ed8\u304d\u306e\u4f7f\u7528\u65b9\u6cd5\n        String processedName3 = Objects.requireNonNull(name, () -&gt; \"\u540d\u524d\u304c\" + System.currentTimeMillis() + \"\u306bnull\u3067\u3057\u305f\");\n\n        System.out.println(\"\u51e6\u7406\u3055\u308c\u305f\u540d\u524d: \" + processedName);\n    }\n\n    public static void main(String[] args) {\n        processName(\"John\"); \/\/ \u6b63\u5e38\u306b\u52d5\u4f5c\n        processName(null);   \/\/ NullPointerException\u304c\u30b9\u30ed\u30fc\u3055\u308c\u308b\n    }\n}<\/pre>\n\n\n<div id=\"sgb-css-id-62\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#009EF3;color:#FFF\" class=\"sgb-box-simple__title\">\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#009EF3;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-60\">\n<li>null\u306e\u5834\u5408\u306b\u5373\u5ea7\u306bNullPointerException\u3092\u30b9\u30ed\u30fc\u3059\u308b<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-61\">\n<li>\u30e1\u30bd\u30c3\u30c9\u306e\u524d\u63d0\u6761\u4ef6\u3092\u660e\u793a\u7684\u306b\u793a\u305b\u308b<\/li>\n<\/div>\n\n\n<li>\u30c7\u30d0\u30c3\u30b0\u304c\u5bb9\u6613\u306b\u306a\u308b<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-64\">\n<div class=\"wp-block-sgb-block-simple sgb-box-simple sgb-box-simple--title-normal sgb-box-simple--with-border\"><div style=\"background-color:#f88080;color:#FFF\" class=\"sgb-box-simple__title\">\u30c7\u30e1\u30ea\u30c3\u30c8<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#f88080;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-63\">\n<li>\u4f8b\u5916\u3092\u30ad\u30e3\u30c3\u30c1\u3057\u3066\u51e6\u7406\u3059\u308b\u5fc5\u8981\u304c\u3042\u308b<\/li>\n<\/div>\n\n\n<li>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306b\u82e5\u5e72\u306e\u5f71\u97ff\u304c\u3042\u308b\u53ef\u80fd\u6027\u304c\u3042\u308b<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-65\">\n<h3 class=\"wp-block-heading\" id=\"i-11\">\u4f7f\u3044\u5206\u3051\u306e\u30ac\u30a4\u30c9\u30e9\u30a4\u30f3<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-68\">\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\u3044\u5206\u3051\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-66\">\n<li><code>Objects.isNull()<\/code>\u3068<code>Objects.nonNull()<\/code>\u306f\u3001\u660e\u793a\u7684\u306anull\u30c1\u30a7\u30c3\u30af\u304c\u5fc5\u8981\u306a\u5834\u5408\u306b\u4f7f\u7528<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-67\">\n<li><code>Objects.requireNonNull()<\/code>\u306f\u3001null\u3092\u8a31\u5bb9\u3057\u306a\u3044\u30e1\u30bd\u30c3\u30c9\u306e\u5f15\u6570\u30c1\u30a7\u30c3\u30af\u306b\u4f7f\u7528<\/li>\n<\/div>\n\n\n<li>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u304c\u8ab2\u984c\u306a\u5834\u5408\u306f\u3001\u5f93\u6765\u306e<code>== null<\/code>\u3084<code>!= null<\/code>\u3092\u4f7f\u7528\u3059\u308b\u3053\u3068\u3092\u691c\u8a0e<\/li>\n<\/ol>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-69\">\n<h3 class=\"wp-block-heading\" id=\"i-12\">\u6f14\u7fd2\u554f\u984c<\/h3>\n<\/div>\n\n\n<ol class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-70\">\n<li><code>Objects.isNull()<\/code>\u3068<code>Objects.nonNull()<\/code>\u3092\u4f7f\u7528\u3057\u3066\u3001\u30ea\u30b9\u30c8\u306e\u8981\u7d20\u304cnull\u304b\u3069\u3046\u304b\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b\u95a2\u6570\u3092\u5b9f\u88c5\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-71\">\n<li><code>Objects.requireNonNull()<\/code>\u3092\u4f7f\u7528\u3057\u3066\u3001\u30e6\u30fc\u30b6\u30fc\u767b\u9332\u30e1\u30bd\u30c3\u30c9\u3067\u5fc5\u9808\u30d5\u30a3\u30fc\u30eb\u30c9\u3092\u30c1\u30a7\u30c3\u30af\u3059\u308b\u51e6\u7406\u3092\u5b9f\u88c5\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/li>\n<\/div><\/ol>\n\n\n<div id=\"sgb-css-id-72\">\n<p>\u3053\u308c\u3089\u306eJava 7\u4ee5\u964d\u3067\u5c0e\u5165\u3055\u308c\u305fnull\u30c1\u30a7\u30c3\u30af\u30e1\u30bd\u30c3\u30c9\u3092\u9069\u5207\u306b\u4f7f\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u5805\u7262\u3067\u8aad\u307f\u3084\u3059\u3044\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001Java 8\u3067\u5c0e\u5165\u3055\u308c\u305f<code>Optional&lt;T&gt;<\/code>\u30af\u30e9\u30b9\u306b\u3064\u3044\u3066\u5b66\u3093\u3067\u3044\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-73\">\n<h2 class=\"wp-block-heading\" id=\"i-13\">4. Java 8\u3067\u9769\u65b0\uff1aOptional\u30af\u30e9\u30b9\u306e\u6d3b\u7528<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-74\">\n<p>Java 8\u3067\u5c0e\u5165\u3055\u308c\u305f<code>Optional&lt;T&gt;<\/code>\u30af\u30e9\u30b9\u306f\u3001null\u3092\u5b89\u5168\u306b\u6271\u3046\u305f\u3081\u306e\u30b3\u30f3\u30c6\u30ca\u30af\u30e9\u30b9\u3067\u3059\u3002\u3053\u306e\u30af\u30e9\u30b9\u306e\u4e3b\u306a\u76ee\u7684\u306f\u3001NullPointerException\u3092\u9632\u304e\u3001null\u306e\u5b58\u5728\u3092\u660e\u793a\u7684\u306b\u8868\u73fe\u3059\u308b\u3053\u3068\u3067\u3001\u5024\u304c\u5b58\u5728\u3057\u306a\u3044\u53ef\u80fd\u6027\u306e\u3042\u308b\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3092\u6271\u3044\u3084\u3059\u304f\u3059\u308b\u3053\u3068\u3067\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-75\">\n<h3 class=\"wp-block-heading\" id=\"i-14\">Optional.ofNullable()\u3067null\u5b89\u5168\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-76\">\n<p><code>Optional.ofNullable()<\/code>\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3059\u308b\u3068\u3001null\u3092\u542b\u3080\u53ef\u80fd\u6027\u306e\u3042\u308b\u5024\u3092\u5b89\u5168\u306bOptional\u3067\u30e9\u30c3\u30d7\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 possiblyNullString = getSomeString();\nOptional&lt;String&gt; opt = Optional.ofNullable(possiblyNullString);<\/pre>\n\n\n<div id=\"sgb-css-id-77\">\n<p>\u3053\u306e\u3088\u3046\u306b\u30e9\u30c3\u30d7\u3059\u308b\u3053\u3068\u3067\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306anull\u306b\u5bfe\u3059\u308b\u5b89\u5168\u306a\u30b3\u30fc\u30c9\u3092\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=\"\">opt.ifPresent(str -&gt; System.out.println(\"String value: \" + str));\n\nString result = opt.map(String::toUpperCase)\n                   .orElse(\"No value present\");<\/pre>\n\n\n<div id=\"sgb-css-id-78\">\n<p><code>Optional&lt;T&gt;<\/code>\u30af\u30e9\u30b9\u306f\u3001\u69d8\u3005\u306a\u4fbf\u5229\u306a\u30e1\u30bd\u30c3\u30c9\u3092\u63d0\u4f9b\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-82\">\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&lt;T&gt;<\/code> \u30af\u30e9\u30b9\u306e\u4fbf\u5229\u306a\u30e1\u30bd\u30c3\u30c9<\/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-79\">\n<li><code>isPresent()<\/code>\uff1a \u5024\u304c\u5b58\u5728\u3059\u308b\u304b\u3069\u3046\u304b\u3092\u78ba\u8a8d<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-80\">\n<li><code>ifPresent(Consumer&lt;T&gt;)<\/code>\uff1a \u5024\u304c\u5b58\u5728\u3059\u308b\u5834\u5408\u306b\u51e6\u7406\u3092\u5b9f\u884c<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-81\">\n<li><code>map(Function&lt;T,U&gt;)<\/code>\uff1a \u5024\u304c\u5b58\u5728\u3059\u308b\u5834\u5408\u306b\u5909\u63db\u3092\u9069\u7528<\/li>\n<\/div>\n\n\n<li><code>flatMap(Function&lt;T,Optional&lt;U&gt;&gt;)<\/code>\uff1a \u5024\u304c\u5b58\u5728\u3059\u308b\u5834\u5408\u306b\u5225\u306eOptional\u3092\u8fd4\u3059\u5909\u63db\u3092\u9069\u7528<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-83\">\n<h3 class=\"wp-block-heading\" id=\"i-15\">orElse()\u3068orElseGet()\u306e\u4f7f\u3044\u5206\u3051<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-84\">\n<p><code>Optional&lt;T&gt;<\/code>\u30af\u30e9\u30b9\u306f\u3001\u5024\u304c\u5b58\u5728\u3057\u306a\u3044\u5834\u5408\u306e\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u63d0\u4f9b\u3059\u308b\u305f\u3081\u306e\u30e1\u30bd\u30c3\u30c9\u3082\u7528\u610f\u3057\u3066\u3044\u307e\u3059\u3002\u4e3b\u306b\u4f7f\u7528\u3055\u308c\u308b\u306e\u306f<code>orElse()<\/code>\u3068<code>orElseGet()<\/code>\u3067\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-85\">\n<h4 class=\"wp-block-heading\" id=\"i-16\">orElse()\u306e\u4f7f\u7528<\/h4>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">String result = opt.orElse(\"Default value\");<\/pre>\n\n\n<div id=\"sgb-css-id-86\">\n<p><code>orElse()<\/code>\u306f\u3001Optional\u304c\u7a7a\u306e\u5834\u5408\u306b\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u8fd4\u3057\u307e\u3059\u3002\u305f\u3060\u3057\u3001\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u306f\u5e38\u306b\u8a55\u4fa1\u3055\u308c\u308b\u305f\u3081\u3001\u6ce8\u610f\u304c\u5fc5\u8981\u3067\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-87\">\n<h4 class=\"wp-block-heading\" id=\"i-17\">orElseGet()\u306e\u4f7f\u7528<\/h4>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">String result = opt.orElseGet(() -&gt; computeDefault());<\/pre>\n\n\n<div id=\"sgb-css-id-88\">\n<p><code>orElseGet()<\/code>\u306f\u3001Optional\u304c\u7a7a\u306e\u5834\u5408\u306b\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u751f\u6210\u3059\u308b\u95a2\u6570\u3092\u5b9f\u884c\u3057\u307e\u3059\u3002\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u306e\u751f\u6210\u306f\u5fc5\u8981\u306a\u5834\u5408\u306e\u307f\u884c\u308f\u308c\u308b\u305f\u3081\uff08\u9045\u5ef6\u8a55\u4fa1\uff09\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u306e\u89b3\u70b9\u304b\u3089\u512a\u308c\u3066\u3044\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-89\">\n<h4 class=\"wp-block-heading\" id=\"i-18\">orElse()\u3068orElseGet()\u306e\u9055\u3044\u3068\u4f7f\u3044\u5206\u3051<\/h4>\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\">\u4f7f\u3044\u5206\u3051<\/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-90\">\n<li><code>orElse()<\/code>\u306f\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u5373\u6642\u8a55\u4fa1\u3057\u307e\u3059\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-91\">\n<li><code>orElseGet()<\/code>\u306f\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u3092\u9045\u5ef6\u8a55\u4fa1\u3057\u307e\u3059\u3002<\/li>\n<\/div>\n\n\n<li>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u30af\u30ea\u30c6\u30a3\u30ab\u30eb\u306a\u5834\u5408\u3084\u3001\u30c7\u30d5\u30a9\u30eb\u30c8\u5024\u306e\u751f\u6210\u30b3\u30b9\u30c8\u304c\u9ad8\u3044\u5834\u5408\u306f<code>orElseGet()<\/code>\u3092\u4f7f\u7528\u3057\u307e\u3057\u3087\u3046\u3002<\/li>\n<\/ol>\n<\/div><\/div>\n\n\n<div id=\"sgb-css-id-92\">\n<h3 class=\"wp-block-heading\" id=\"i-19\">Optional\u4f7f\u7528\u6642\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/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\">\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-93\">\n<li><code>Optional&lt;T&gt;<\/code>\u3092\u30e1\u30bd\u30c3\u30c9\u306e\u623b\u308a\u5024\u578b\u3068\u3057\u3066\u4f7f\u7528\u3059\u308b\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-94\">\n<li><code>Optional&lt;T&gt;<\/code>\u3092\u30d5\u30a3\u30fc\u30eb\u30c9\u3084\u30e1\u30bd\u30c3\u30c9\u306e\u5f15\u6570\u3068\u3057\u3066\u4f7f\u7528\u3057\u306a\u3044\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-95\">\n<li>\u57fa\u672c\u578b\u306eOptional\u3092\u4f7f\u7528\u3059\u308b\uff08<code>OptionalInt<\/code>, <code>OptionalLong<\/code>, <code>OptionalDouble<\/code>\uff09\u3002<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-96\">\n<li>\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u306b\u5bfe\u3057\u3066\u306f<code>Optional<\/code>\u306e\u4ee3\u308f\u308a\u306b\u7a7a\u306e\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3092\u8fd4\u3059\u3002<\/li>\n<\/div>\n\n\n<li><code>Optional.get()<\/code>\u306e\u4f7f\u7528\u3092\u907f\u3051\u3001\u3088\u308a\u5b89\u5168\u306a\u30e1\u30bd\u30c3\u30c9\u3092\u4f7f\u7528\u3059\u308b\u3002<\/li>\n<\/ol>\n<\/div><\/div>\n\n\n<div id=\"sgb-css-id-97\">\n<p><code>Optional&lt;T&gt;<\/code>\u30af\u30e9\u30b9\u3092\u9069\u5207\u306b\u6d3b\u7528\u3059\u308b\u3053\u3068\u3067\u3001null\u306b\u8d77\u56e0\u3059\u308b\u30d0\u30b0\u3092\u5927\u5e45\u306b\u6e1b\u3089\u3057\u3001\u30b3\u30fc\u30c9\u306e\u53ef\u8aad\u6027\u3068\u4fdd\u5b88\u6027\u3092\u5411\u4e0a\u3055\u305b\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u8003\u616e\u3057\u305fnull\u30c1\u30a7\u30c3\u30af\u624b\u6cd5\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u898b\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-98\">\n<h2 class=\"wp-block-heading\" id=\"i-20\">5. \u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u8003\u616e\u3057\u305fnull\u30c1\u30a7\u30c3\u30af\u624b\u6cd5<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-99\">\n<p>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3092\u8003\u616e\u3057\u305fnull\u30c1\u30a7\u30c3\u30af\u306f\u3001\u7279\u306b\u5927\u898f\u6a21\u30a2\u30d7\u30ea\u30b1\u30fc\u30b7\u30e7\u30f3\u3084\u9ad8\u8ca0\u8377\u30b7\u30b9\u30c6\u30e0\u306b\u304a\u3044\u3066\u91cd\u8981\u3067\u3059\u3002\u9069\u5207\u306a\u624b\u6cd5\u3092\u9078\u629e\u3059\u308b\u3053\u3068\u3067\u3001\u51e6\u7406\u901f\u5ea6\u306e\u6700\u9069\u5316\u3068\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u306e\u524a\u6e1b\u3092\u5b9f\u73fe\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-100\">\n<h3 class=\"wp-block-heading\" id=\"i-21\">== null\u3068!= null\u306e\u52b9\u7387\u7684\u306a\u4f7f\u7528\u6cd5<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-101\">\n<p>Java\u306b\u304a\u3044\u3066\u3001<code>== null<\/code>\u3068<code>!= null<\/code>\u306f\u6700\u3082\u57fa\u672c\u7684\u3067\u52b9\u7387\u7684\u306anull\u30c1\u30a7\u30c3\u30af\u65b9\u6cd5\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=\"\">if (object == null) {\n    \/\/ null\u306e\u5834\u5408\u306e\u51e6\u7406\n} else if (object != null) {\n    \/\/ null\u3067\u306a\u3044\u5834\u5408\u306e\u51e6\u7406\n}<\/pre>\n\n\n<div id=\"sgb-css-id-102\">\n<p>\u3053\u308c\u3089\u306e\u6f14\u7b97\u5b50\u306f\u4ee5\u4e0b\u306e\u7279\u5fb4\u3092\u6301\u3061\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-105\">\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>== null<\/code>\u3068<code>!= null<\/code> \u306e\u7279\u5fb4<\/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-103\">\n<li>JVM\u306b\u3088\u308b\u6700\u9069\u5316\u304c\u884c\u308f\u308c\u3084\u3059\u3044<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-104\">\n<li>\u30e1\u30e2\u30ea\u30a2\u30af\u30bb\u30b9\u304c\u6700\u5c0f\u9650<\/li>\n<\/div>\n\n\n<li>\u4ed6\u306enull\u30c1\u30a7\u30c3\u30af\u65b9\u6cd5\u3068\u6bd4\u8f03\u3057\u3066\u9ad8\u901f<\/li>\n<\/ol>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-108\">\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<\/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-106\">\n<li>\u983b\u7e41\u306b\u5b9f\u884c\u3055\u308c\u308b\u51e6\u7406\u3067\u306f <code>== null<\/code> \u3084 <code>!= null<\/code> \u3092\u512a\u5148\u3059\u308b<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-107\">\n<li>\u53ef\u8aad\u6027\u3092\u640d\u306a\u308f\u306a\u3044\u7bc4\u56f2\u3067\u4f7f\u7528\u3059\u308b<\/li>\n<\/div>\n\n\n<li>\u8907\u96d1\u306a\u6761\u4ef6\u5f0f\u3067\u306f <code>Objects.isNull()<\/code> \u3084 <code>Objects.nonNull()<\/code> \u3092\u691c\u8a0e\u3059\u308b<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-109\">\n<h3 class=\"wp-block-heading\" id=\"i-22\">\u5927\u898f\u6a21\u51e6\u7406\u3067\u306e\u6700\u9069\u306anull\u30c1\u30a7\u30c3\u30af\u6226\u7565<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-110\">\n<p>\u5927\u898f\u6a21\u30c7\u30fc\u30bf\u51e6\u7406\u6642\u306b\u306f\u3001null\u30c1\u30a7\u30c3\u30af\u306b\u3088\u308b\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u4f4e\u4e0b\u3084\u30e1\u30e2\u30ea\u4f7f\u7528\u91cf\u306e\u5897\u52a0\u304c\u8ab2\u984c\u3068\u306a\u308a\u307e\u3059\u3002\u4ee5\u4e0b\u306e\u6226\u7565\u3092\u9069\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u3053\u308c\u3089\u306e\u554f\u984c\u306b\u5bfe\u51e6\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n\n<ol class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-111\">\n<li>\u65e9\u671f\u30ea\u30bf\u30fc\u30f3\u30d1\u30bf\u30fc\u30f3<\/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=\"\">public void processData(List&lt;String&gt; data) {\n    if (data == null || data.isEmpty()) {\n        return;\n    }\n    \/\/ \u4ee5\u964d\u306e\u51e6\u7406\n}<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-112\">\n<li>\u30b9\u30c8\u30ea\u30fc\u30e0API\u3068Optional\u306e\u7d44\u307f\u5408\u308f\u305b<\/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=\"\">List&lt;String&gt; result = data.stream()\n    .filter(Objects::nonNull)\n    .map(String::toUpperCase)\n    .collect(Collectors.toList());<\/pre>\n\n\n<div id=\"sgb-css-id-114\">\n<ol start=\"3\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-113\">\n<li>\u4e26\u5217\u30b9\u30c8\u30ea\u30fc\u30e0\u306e\u6d3b\u7528<\/li>\n<\/div><\/ol>\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=\"\">List&lt;String&gt; result = data.parallelStream()\n    .filter(Objects::nonNull)\n    .map(this::heavyProcessing)\n    .collect(Collectors.toList());<\/pre>\n\n\n<div id=\"sgb-css-id-116\">\n<ol start=\"4\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-115\">\n<li>\u30d0\u30eb\u30af\u51e6\u7406\u306e\u305f\u3081\u306e\u30ab\u30b9\u30bf\u30e0\u30e6\u30fc\u30c6\u30a3\u30ea\u30c6\u30a3\u30e1\u30bd\u30c3\u30c9<\/li>\n<\/div><\/ol>\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 &lt;T&gt; List&lt;T&gt; filterNonNull(List&lt;T&gt; list) {\n    return list.stream()\n        .filter(Objects::nonNull)\n        .collect(Collectors.toList());\n}<\/pre>\n\n\n<div id=\"sgb-css-id-117\">\n<p>\u3053\u308c\u3089\u306e\u6226\u7565\u3092\u9069\u7528\u3059\u308b\u969b\u306f\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u3068\u30b3\u30fc\u30c9\u53ef\u8aad\u6027\u306e\u30d0\u30e9\u30f3\u30b9\u3092\u53d6\u308b\u3053\u3068\u304c\u91cd\u8981\u3067\u3059\u3002\u904e\u5ea6\u306a\u6700\u9069\u5316\u306f\u30b3\u30fc\u30c9\u306e\u610f\u56f3\u3092\u4e0d\u660e\u78ba\u306b\u3059\u308b\u53ef\u80fd\u6027\u304c\u3042\u308b\u305f\u3081\u3001\u30c1\u30fc\u30e0\u306e\u958b\u767a\u30ac\u30a4\u30c9\u30e9\u30a4\u30f3\u306b\u5f93\u3044\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u30af\u30ea\u30c6\u30a3\u30ab\u30eb\u306a\u90e8\u5206\u306e\u307f\u3092\u6700\u9069\u5316\u3059\u308b\u3053\u3068\u3092\u304a\u3059\u3059\u3081\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-118\">\n<p>\u6700\u5f8c\u306b\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u6700\u9069\u5316\u306e\u52b9\u679c\u3092\u78ba\u8a8d\u3059\u308b\u305f\u3081\u3001\u5b9f\u969b\u306b\u6e2c\u5b9a\u3092\u884c\u3046\u3053\u3068\u304c\u4e0d\u53ef\u6b20\u3067\u3059\u3002JMH\u306a\u3069\u306e\u30de\u30a4\u30af\u30ed\u30d9\u30f3\u30c1\u30de\u30fc\u30af\u30c4\u30fc\u30eb\u3084\u30d7\u30ed\u30d5\u30a1\u30a4\u30ea\u30f3\u30b0\u30c4\u30fc\u30eb\u3092\u6d3b\u7528\u3057\u3001\u5b9f\u969b\u306e\u4f7f\u7528\u30b7\u30ca\u30ea\u30aa\u3067\u306e\u30a8\u30f3\u30c9\u30c4\u30fc\u30a8\u30f3\u30c9\u30c6\u30b9\u30c8\u3092\u884c\u3046\u3053\u3068\u3067\u3001\u6700\u9069\u5316\u306e\u52b9\u679c\u3092\u5b9a\u91cf\u7684\u306b\u8a55\u4fa1\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-119\">\n<p>\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u30b3\u30fc\u30c9\u54c1\u8cea\u5411\u4e0a\u306e\u305f\u3081\u306enull\u30c1\u30a7\u30c3\u30af\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u898b\u3066\u3044\u304d\u307e\u3059\u3002\u3053\u308c\u3089\u306e\u624b\u6cd5\u3092\u7d44\u307f\u5408\u308f\u305b\u308b\u3053\u3068\u3067\u3001\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u3068\u54c1\u8cea\u306e\u4e21\u9762\u3067\u512a\u308c\u305fJava\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-120\">\n<h2 class=\"wp-block-heading\" id=\"i-23\">6. \u30b3\u30fc\u30c9\u54c1\u8cea\u5411\u4e0a\u306e\u305f\u3081\u306enull\u30c1\u30a7\u30c3\u30af\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-121\">\n<p>\u9069\u5207\u306anull\u30c1\u30a7\u30c3\u30af\u306f\u30b3\u30fc\u30c9\u54c1\u8cea\u3092\u5927\u304d\u304f\u5411\u4e0a\u3055\u305b\u307e\u3059\u3002\u30d0\u30b0\u306e\u6e1b\u5c11\u3001\u53ef\u8aad\u6027\u306e\u5411\u4e0a\u3001\u4fdd\u5b88\u6027\u306e\u6539\u5584\u3001\u305d\u3057\u3066\u958b\u767a\u8005\u306e\u610f\u56f3\u306e\u660e\u78ba\u5316\u306b\u3064\u306a\u304c\u308a\u307e\u3059\u3002\u3053\u3053\u3067\u306f\u3001null\u30c1\u30a7\u30c3\u30af\u306b\u95a2\u3059\u308b2\u3064\u306e\u91cd\u8981\u306a\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3092\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-122\">\n<h3 class=\"wp-block-heading\" id=\"i-24\">@Nullable, @NonNull\u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3\u306e\u52b9\u679c\u7684\u306a\u6d3b\u7528<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-123\">\n<p><code>@Nullable<\/code>\u3068<code>@NonNull<\/code>\u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3\u306f\u3001null\u306e\u53ef\u80fd\u6027\u3092\u660e\u793a\u7684\u306b\u793a\u3059\u305f\u3081\u306b\u4f7f\u7528\u3055\u308c\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-124\">\n<h4 class=\"wp-block-heading\" id=\"i-25\">@Nullable<\/h4>\n<\/div>\n\n<div id=\"sgb-css-id-125\">\n<p>\u3053\u306e\u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3\u306f\u3001null\u304c\u8a31\u5bb9\u3055\u308c\u308b\u3053\u3068\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=\"\">public @Nullable String getUserName(@Nullable User user) {\n    return Optional.ofNullable(user)\n                   .map(User::getName)\n                   .orElse(null);\n}<\/pre>\n\n\n<div id=\"sgb-css-id-126\">\n<h4 class=\"wp-block-heading\" id=\"i-26\">@NonNull<\/h4>\n<\/div>\n\n<div id=\"sgb-css-id-127\">\n<p>\u3053\u306e\u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3\u306f\u3001null\u304c\u8a31\u5bb9\u3055\u308c\u306a\u3044\u3053\u3068\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=\"\">public void processUser(@NonNull User user) {\n    System.out.println(\"Processing user: \" + user.getName());\n}<\/pre>\n\n\n<div id=\"sgb-css-id-132\">\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\">\u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3\u306e\u4e3b\u306a\u5229\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-128\">\n<li>null\u306e\u53ef\u80fd\u6027\u3092\u660e\u793a\u7684\u306b\u793a\u3059<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-129\">\n<li>\u9759\u7684\u89e3\u6790\u30c4\u30fc\u30eb\u306b\u3088\u308b\u8b66\u544a<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-130\">\n<li>\u30c9\u30ad\u30e5\u30e1\u30f3\u30c8\u3068\u3057\u3066\u306e\u5f79\u5272<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-131\">\n<li>\u4e0d\u8981\u306anull\u30c1\u30a7\u30c3\u30af\u306e\u524a\u6e1b<\/li>\n<\/div>\n\n\n<li>NullPointerException\u306e\u30ea\u30b9\u30af\u4f4e\u6e1b<\/li>\n<\/ol>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-135\">\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<\/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-133\">\n<li>\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u5168\u4f53\u3067\u4e00\u8cab\u3057\u3066\u4f7f\u7528\u3059\u308b<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-134\">\n<li>\u5916\u90e8\u30e9\u30a4\u30d6\u30e9\u30ea\u3068\u306e\u9023\u643a\u6642\u306b\u7279\u306b\u6709\u52b9<\/li>\n<\/div>\n\n\n<li>IDE\u3084\u30d3\u30eb\u30c9\u30c4\u30fc\u30eb\u3068\u9023\u643a\u3057\u3066\u6d3b\u7528\u3059\u308b<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-136\">\n<h3 class=\"wp-block-heading\" id=\"i-27\">\u9632\u5fa1\u7684\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u3067null\u8d77\u56e0\u306e\u30d0\u30b0\u3092\u4e88\u9632<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-137\">\n<p>\u9632\u5fa1\u7684\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u306f\u3001\u4e88\u671f\u3057\u306a\u3044\u72b6\u6cc1\u3084\u30a8\u30e9\u30fc\u306b\u5bfe\u3057\u3066\u5805\u7262\u306a\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u624b\u6cd5\u3067\u3059\u3002null\u95a2\u9023\u306e\u30d0\u30b0\u4e88\u9632\u306b\u7279\u306b\u6709\u52b9\u3067\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-138\">\n<h4 class=\"wp-block-heading\" id=\"i-28\">\u5177\u4f53\u7684\u306a\u6280\u6cd5\uff1a<\/h4>\n<\/div>\n\n\n<ol class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-139\">\n<li>\u65e9\u671f\u306enull\u30c1\u30a7\u30c3\u30af\u3068\u4f8b\u5916\u30b9\u30ed\u30fc<\/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=\"\">public void processData(String data) {\n    Objects.requireNonNull(data, \"Data must not be null\");\n    \/\/ \u51e6\u7406\u7d9a\u884c\n}<\/pre>\n\n\n\n<ol start=\"2\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-140\">\n<li>Null Object\u30d1\u30bf\u30fc\u30f3\u306e\u9069\u7528<\/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=\"\">public class NullUser implements User {\n    @Override\n    public String getName() {\n        return \"Guest\";\n    }\n    \/\/ \u305d\u306e\u4ed6\u306e\u30e1\u30bd\u30c3\u30c9\u5b9f\u88c5\n}<\/pre>\n\n\n\n<ol start=\"3\" class=\"wp-block-list is-style-sango-list-simple\"><div id=\"sgb-css-id-141\">\n<li>Optional\u306e\u6d3b\u7528<\/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=\"\">public String getUserName(User user) {\n    return Optional.ofNullable(user)\n                   .map(User::getName)\n                   .orElse(\"Unknown\");\n}<\/pre>\n\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\">\u30b3\u30fc\u30c9\u30ec\u30d3\u30e5\u30fc\u306e\u30dd\u30a4\u30f3\u30c8<\/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-142\">\n<li>@Nullable, @NonNull\u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3\u306e\u4e00\u8cab\u3057\u305f\u4f7f\u7528<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-143\">\n<li>\u4e0d\u5fc5\u8981\u306anull\u30c1\u30a7\u30c3\u30af\u306e\u6392\u9664<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-144\">\n<li>\u9069\u5207\u306a\u5834\u6240\u3067\u306eOptional\u306e\u4f7f\u7528<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-145\">\n<li>\u9632\u5fa1\u7684\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u6280\u6cd5\u306e\u9069\u7528<\/li>\n<\/div>\n\n\n<li>null\u306e\u610f\u5473\u3084\u51e6\u7406\u306e\u660e\u78ba\u5316<\/li>\n<\/ol>\n<\/div><\/div>\n\n\n<div id=\"sgb-css-id-146\">\n<p>\u3053\u308c\u3089\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3092\u9069\u7528\u3059\u308b\u3053\u3068\u3067\u3001null\u306b\u8d77\u56e0\u3059\u308b\u30d0\u30b0\u3092\u5927\u5e45\u306b\u6e1b\u3089\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\u3001null\u30c1\u30a7\u30c3\u30af\u306b\u95a2\u3059\u308b\u3088\u304f\u3042\u308b\u9593\u9055\u3044\u3068\u6ce8\u610f\u70b9\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u898b\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-147\">\n<h2 class=\"wp-block-heading\" id=\"i-29\">7. \u3088\u304f\u3042\u308b\u9593\u9055\u3044\u3068\u6ce8\u610f\u70b9<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-148\">\n<p>null\u30c1\u30a7\u30c3\u30af\u3092\u884c\u3046\u969b\u3001\u3044\u304f\u3064\u304b\u306e\u843d\u3068\u3057\u7a74\u304c\u3042\u308a\u307e\u3059\u3002\u3053\u3053\u3067\u306f\u3001\u7279\u306b\u6ce8\u610f\u304c\u5fc5\u8981\u306a2\u3064\u306e\u4e8b\u4f8b\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u898b\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-149\">\n<h3 class=\"wp-block-heading\" id=\"i-30\">String.valueOf()\u306e\u843d\u3068\u3057\u7a74\u3068\u5bfe\u7b56<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-150\">\n<p><code>String.valueOf()<\/code>\u306f\u4fbf\u5229\u306a\u30e1\u30bd\u30c3\u30c9\u3067\u3059\u304c\u3001null\u306e\u6271\u3044\u306b\u6ce8\u610f\u304c\u5fc5\u8981\u3067\u3059\u3002<\/p>\n<\/div>\n\n\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"generic\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">Object obj = null;\nString result = String.valueOf(obj); \/\/ \u7d50\u679c\u306f \"null\" (\u6587\u5b57\u5217)<\/pre>\n\n\n<div id=\"sgb-css-id-151\">\n<p>\u3053\u306e\u6319\u52d5\u306f\u3001\u4ee5\u4e0b\u306e\u3088\u3046\u306a\u554f\u984c\u3092\u5f15\u304d\u8d77\u3053\u3059\u53ef\u80fd\u6027\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-153\">\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\">\u5f15\u304d\u8d77\u3053\u3059\u53ef\u80fd\u6027\u306e\u3042\u308b\u554f\u984c<\/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-152\">\n<li>\u610f\u56f3\u3057\u306a\u3044 \u201cnull\u201d \u6587\u5b57\u5217\u306e\u751f\u6210<\/li>\n<\/div>\n\n\n<li>NullPointerException\u3092\u9632\u3052\u306a\u3044\u30b1\u30fc\u30b9\u304c\u3042\u308b<\/li>\n<\/ol>\n<\/div><\/div>\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\">\u554f\u984c\u3078\u306e\u5bfe\u7b56<\/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-154\">\n<li>null\u30c1\u30a7\u30c3\u30af\u3092\u5148\u306b\u884c\u3046<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-155\">\n<li>Optional\u3092\u4f7f\u7528\u3059\u308b<\/li>\n<\/div>\n\n\n<li>Objects.toString(obj, defaultValue)\u3092\u4f7f\u7528\u3059\u308b<\/li>\n<\/ol>\n<\/div><\/div>\n\n\n<div id=\"sgb-css-id-156\">\n<p>\u6539\u5584\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=\"\">String result = Optional.ofNullable(someObject)\n                        .map(Object::toString)\n                        .orElse(\"\");<\/pre>\n\n\n<div id=\"sgb-css-id-157\">\n<p>\u307e\u305f\u306f\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=\"\">String result = Objects.toString(someObject, \"\");<\/pre>\n\n\n<div id=\"sgb-css-id-158\">\n<h3 class=\"wp-block-heading\" id=\"i-31\">\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3068\u30de\u30c3\u30d7\u306enull\u30c1\u30a7\u30c3\u30af\u306e\u52d8\u6240<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-159\">\n<p>\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3068\u30de\u30c3\u30d7\u306enull\u30c1\u30a7\u30c3\u30af\u306f\u3001\u8907\u6570\u306e\u5074\u9762\u3092\u8003\u616e\u3059\u308b\u5fc5\u8981\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-160\">\n<h4 class=\"wp-block-heading\" id=\"i-32\">\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u306enull\u30c1\u30a7\u30c3\u30af<\/h4>\n<\/div>\n\n<div id=\"sgb-css-id-163\">\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\">\u6ce8\u610f\u70b9<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#ffb36b;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-161\">\n<li>\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u81ea\u4f53\u304cnull\u306e\u53ef\u80fd\u6027<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-162\">\n<li>\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u5185\u306e\u8981\u7d20\u304cnull\u306e\u53ef\u80fd\u6027<\/li>\n<\/div>\n\n\n<li>\u7a7a\u306e\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3068null\u306e\u533a\u5225<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-164\">\n<p>\u9069\u5207\u306a\u65b9\u6cd5\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=\"\">List&lt;String&gt; result = Optional.ofNullable(someList)\n                              .orElse(Collections.emptyList());\n\nList&lt;String&gt; nonNullElements = result.stream()\n                                     .filter(Objects::nonNull)\n                                     .collect(Collectors.toList());<\/pre>\n\n\n<div id=\"sgb-css-id-165\">\n<h4 class=\"wp-block-heading\" id=\"i-33\">\u30de\u30c3\u30d7\u306enull\u30c1\u30a7\u30c3\u30af<\/h4>\n<\/div>\n\n<div id=\"sgb-css-id-168\">\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\">\u6ce8\u610f\u70b9<\/div><div class=\"sgb-box-simple__body\" style=\"border-color:#ffb36b;background-color:#FFF\">\n<ul class=\"wp-block-list\"><div id=\"sgb-css-id-166\">\n<li>\u30de\u30c3\u30d7\u81ea\u4f53\u304cnull\u306e\u53ef\u80fd\u6027<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-167\">\n<li>\u30ad\u30fc\u304cnull\u306e\u53ef\u80fd\u6027<\/li>\n<\/div>\n\n\n<li>\u5024\u304cnull\u306e\u53ef\u80fd\u6027<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-169\">\n<p>\u9069\u5207\u306a\u65b9\u6cd5\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=\"\">Map&lt;String, Integer&gt; safeMap = Optional.ofNullable(someMap)\n                                       .orElse(Collections.emptyMap());\n\nInteger value = safeMap.getOrDefault(\"key\", 0);\n\nsafeMap.computeIfAbsent(\"key\", k -&gt; calculateValue(k));<\/pre>\n\n\n<div id=\"sgb-css-id-172\">\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<\/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-170\">\n<li>\u9632\u5fa1\u7684\u30b3\u30d4\u30fc\u306e\u4f7f\u7528<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-171\">\n<li>\u4e0d\u5909\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u306e\u6d3b\u7528<\/li>\n<\/div>\n\n\n<li>null-safe\u306a\u30e6\u30fc\u30c6\u30a3\u30ea\u30c6\u30a3\u30e1\u30bd\u30c3\u30c9\u306e\u4f5c\u6210<\/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 &lt;T&gt; List&lt;T&gt; nullSafeList(List&lt;T&gt; list) {\n    return list == null ? Collections.emptyList() : list;\n}<\/pre>\n\n\n<div id=\"sgb-css-id-173\">\n<p>\u3053\u308c\u3089\u306e\u6ce8\u610f\u70b9\u3092\u5ff5\u982d\u306b\u7f6e\u304d\u3001\u9069\u5207\u306anull\u30c1\u30a7\u30c3\u30af\u3092\u884c\u3046\u3053\u3068\u3067\u3001\u3088\u308a\u5805\u7262\u3067\u4fe1\u983c\u6027\u306e\u9ad8\u3044\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002\u6b21\u306e\u30bb\u30af\u30b7\u30e7\u30f3\u3067\u306f\u3001\u3053\u308c\u307e\u3067\u306b\u5b66\u3093\u3060\u5185\u5bb9\u3092\u7dcf\u62ec\u3057\u3001\u52b9\u679c\u7684\u306anull\u30c1\u30a7\u30c3\u30af\u306e\u7dcf\u5408\u7684\u306a\u6226\u7565\u306b\u3064\u3044\u3066\u8003\u3048\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-174\">\n<h2 class=\"wp-block-heading\" id=\"i-34\">8. \u307e\u3068\u3081\uff1a\u52b9\u679c\u7684\u306anull\u30c1\u30a7\u30c3\u30af\u3067\u5805\u7262\u306aJava\u30b3\u30fc\u30c9\u3092<\/h2>\n<\/div>\n\n<div id=\"sgb-css-id-175\">\n<p>\u672c\u8a18\u4e8b\u3067\u306f\u3001Java\u306b\u304a\u3051\u308b\u52b9\u679c\u7684\u306anull\u30c1\u30a7\u30c3\u30af\u624b\u6cd5\u306b\u3064\u3044\u3066\u8a73\u3057\u304f\u89e3\u8aac\u3057\u3066\u304d\u307e\u3057\u305f\u3002\u3053\u3053\u3067\u5b66\u3093\u3060\u5185\u5bb9\u3092\u9069\u5207\u306b\u6d3b\u7528\u3059\u308b\u3053\u3068\u3067\u3001\u3088\u308a\u5805\u7262\u3067\u4fdd\u5b88\u6027\u306e\u9ad8\u3044\u30b3\u30fc\u30c9\u3092\u66f8\u304f\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-176\">\n<h3 class=\"wp-block-heading\" id=\"i-35\">\u72b6\u6cc1\u306b\u5fdc\u3058\u305f\u9069\u5207\u306anull\u30c1\u30a7\u30c3\u30af\u624b\u6cd5\u306e\u9078\u629e<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-177\">\n<p>null\u30c1\u30a7\u30c3\u30af\u624b\u6cd5\u306e\u9078\u629e\u306f\u3001\u4ee5\u4e0b\u306e\u8981\u56e0\u3092\u8003\u616e\u3057\u3066\u884c\u3044\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-182\">\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\">null\u30c1\u30a7\u30c3\u30af\u624b\u6cd5\u306e\u8003\u616e\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-178\">\n<li>\u30b3\u30fc\u30c9\u306e\u8907\u96d1\u3055<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-179\">\n<li>\u30d1\u30d5\u30a9\u30fc\u30de\u30f3\u30b9\u8981\u4ef6<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-180\">\n<li>\u30c1\u30fc\u30e0\u306e\u958b\u767a\u898f\u7d04<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-181\">\n<li>\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u306e\u8981\u4ef6<\/li>\n<\/div>\n\n\n<li>Java\u306e\u30d0\u30fc\u30b8\u30e7\u30f3<\/li>\n<\/ol>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-187\">\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\">null\u30c1\u30a7\u30c3\u30af\u624b\u6cd5\u9078\u629e\u306e\u4f8b<\/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-183\">\n<li>\u30b7\u30f3\u30d7\u30eb\u306a\u6761\u4ef6\u5206\u5c90\u306b\u306f\u57fa\u672c\u7684\u306aif\u6587<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-184\">\n<li>\u7c21\u6f54\u306a\u6761\u4ef6\u4ed8\u304d\u4ee3\u5165\u306b\u306f\u4e09\u9805\u6f14\u7b97\u5b50<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-185\">\n<li>\u30e1\u30bd\u30c3\u30c9\u53c2\u7167\u3084\u30e9\u30e0\u30c0\u5f0f\u3068\u306e\u7d44\u307f\u5408\u308f\u305b\u306b\u306fObjects.isNull()<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-186\">\n<li>\u5024\u304c\u5b58\u5728\u3057\u306a\u3044\u53ef\u80fd\u6027\u3092\u660e\u793a\u7684\u306b\u8868\u73fe\u3057\u305f\u3044\u5834\u5408\u306fOptional<\/li>\n<\/div>\n\n\n<li>API\u8a2d\u8a08\u6642\u3084\u30e9\u30a4\u30d6\u30e9\u30ea\u958b\u767a\u6642\u306b\u306f@Nullable, @NonNull\u30a2\u30ce\u30c6\u30fc\u30b7\u30e7\u30f3<\/li>\n<\/ul>\n<\/div><\/div>\n<\/div>\n\n<div id=\"sgb-css-id-188\">\n<h3 class=\"wp-block-heading\" id=\"i-36\">\u7d99\u7d9a\u7684\u306a\u5b66\u7fd2\u3068\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u306e\u9069\u7528<\/h3>\n<\/div>\n\n<div id=\"sgb-css-id-189\">\n<p>null\u30c1\u30a7\u30c3\u30af\u306b\u95a2\u3059\u308b\u77e5\u8b58\u3084\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u306f\u5e38\u306b\u9032\u5316\u3057\u3066\u3044\u307e\u3059\u3002\u4ee5\u4e0b\u306e\u70b9\u306b\u6ce8\u610f\u3057\u3066\u3001\u7d99\u7d9a\u7684\u306b\u5b66\u7fd2\u3092\u7d9a\u3051\u307e\u3057\u3087\u3046\u3002<\/p>\n<\/div>\n\n<div id=\"sgb-css-id-192\">\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\">\u7d99\u7d9a\u7684\u306b\u5b66\u7fd2\u306b\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-190\">\n<li>Java\u8a00\u8a9e\u306e\u65b0\u6a5f\u80fd\u3092\u628a\u63e1\u3059\u308b<\/li>\n<\/div>\n\n<div id=\"sgb-css-id-191\">\n<li>\u30b3\u30df\u30e5\u30cb\u30c6\u30a3\u306e\u30d9\u30b9\u30c8\u30d7\u30e9\u30af\u30c6\u30a3\u30b9\u3092\u5b66\u3076<\/li>\n<\/div>\n\n\n<li>\u65b0\u3057\u3044\u30e9\u30a4\u30d6\u30e9\u30ea\u3084\u30d5\u30ec\u30fc\u30e0\u30ef\u30fc\u30af\u306e\u52d5\u5411\u3092\u8ffd\u3046<\/li>\n<\/ol>\n<\/div><\/div>\n<\/div>\n\n\n<p>\u60c5\u5831\u6e90\u3068\u3057\u3066\u3001Java\u516c\u5f0f\u30c9\u30ad\u30e5\u30e1\u30f3\u30c8\u3001\u6280\u8853\u66f8\u7c4d\u3001\u958b\u767a\u8005\u30d6\u30ed\u30b0\u3001\u6280\u8853\u30ab\u30f3\u30d5\u30a1\u30ec\u30f3\u30b9\u3001\u30aa\u30f3\u30e9\u30a4\u30f3\u30b3\u30fc\u30b9\u306a\u3069\u3092\u6d3b\u7528\u3057\u3066\u304f\u3060\u3055\u3044\u3002<\/p>\n\n\n<div id=\"sgb-css-id-193\">\n<p>\u6700\u5f8c\u306b\u3001null\u30c1\u30a7\u30c3\u30af\u306f\u5358\u306a\u308b\u6280\u8853\u7684\u306a\u554f\u984c\u3067\u306f\u306a\u304f\u3001\u30b3\u30fc\u30c9\u54c1\u8cea\u3068\u4fe1\u983c\u6027\u306b\u76f4\u7d50\u3059\u308b\u91cd\u8981\u306a\u8981\u7d20\u3067\u3059\u3002\u672c\u8a18\u4e8b\u3067\u5b66\u3093\u3060\u30c6\u30af\u30cb\u30c3\u30af\u3092\u65e5\u3005\u306e\u958b\u767a\u306b\u9069\u7528\u3057\u3001\u3088\u308a\u826f\u3044Java\u30d7\u30ed\u30b0\u30e9\u30de\u30fc\u3092\u76ee\u6307\u3057\u307e\u3057\u3087\u3046\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":3045,"comment_status":"closed","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2,68],"tags":[],"class_list":{"0":"post-336","1":"post","2":"type-post","3":"status-publish","4":"format-standard","5":"has-post-thumbnail","7":"category-java","8":"category-java-best-practice"},"_links":{"self":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/336","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=336"}],"version-history":[{"count":2,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/336\/revisions"}],"predecessor-version":[{"id":340,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/posts\/336\/revisions\/340"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=\/wp\/v2\/media\/3045"}],"wp:attachment":[{"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=336"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=336"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/dexall.co.jp\/articles\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=336"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}