{"id":670651,"date":"2025-12-23T10:43:16","date_gmt":"2025-12-23T09:43:16","guid":{"rendered":"https:\/\/blog.jetbrains.com\/kotlin\/2025\/10\/getting-started-with-kotlin-for-java-developers\/"},"modified":"2026-01-09T03:30:29","modified_gmt":"2026-01-09T02:30:29","slug":"getting-started-with-kotlin-for-java-developers","status":"publish","type":"kotlin","link":"https:\/\/blog.jetbrains.com\/ja\/kotlin\/2025\/12\/getting-started-with-kotlin-for-java-developers\/","title":{"rendered":"Java \u958b\u767a\u8005\u5411\u3051 Kotlin \u5165\u9580\u30ac\u30a4\u30c9"},"content":{"rendered":"<p><em><a href=\"https:\/\/www.linkedin.com\/in\/urs-peter-70a2882\/\" target=\"_blank\" rel=\"noreferrer noopener\" data-type=\"link\" data-id=\"https:\/\/bit.ly\/urs-peter-linked-in\">Urs Peter<\/a>\uff08\u30b7\u30cb\u30a2\u30bd\u30d5\u30c8\u30a6\u30a7\u30a2\u30a8\u30f3\u30b8\u30cb\u30a2\u3001JetBrains \u8a8d\u5b9a Kotlin \u30c8\u30ec\u30fc\u30ca\u30fc\uff09\u306b\u3088\u308b\u30b2\u30b9\u30c8\u6295\u7a3f\u3067\u3059\u3002 Urs \u306f\u3001\u3088\u308a\u4f53\u7cfb\u7684\u306a Kotlin \u30b9\u30ad\u30eb\u306e\u69cb\u7bc9\u3092\u5e0c\u671b\u3059\u308b\u958b\u767a\u8005\u3092\u5bfe\u8c61\u3068\u3059\u308b <\/em><a href=\"https:\/\/academy.xebia.com\/upskilling\/kotlin-academy\/\" target=\"_blank\" rel=\"noreferrer noopener\"><em>Kotlin Upskill Program<\/em><\/a>\uff08Kotlin \u30b9\u30ad\u30eb\u30a2\u30c3\u30d7\u30d7\u30ed\u30b0\u30e9\u30e0\uff09\u3082 <em>Xebia Academy \u3067<\/em>\u958b\u8b1b\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n<p><em>\u3053\u306e\u8a18\u4e8b\u306f\u3001\u5b9f\u969b\u306e\u30c1\u30fc\u30e0\u306b\u304a\u3044\u3066\u3042\u308b\u4e00\u4eba\u306e\u958b\u767a\u8005\u306e\u597d\u5947\u5fc3\u3092\u304d\u3063\u304b\u3051\u306b\u3001\u4f1a\u793e\u5168\u4f53\u304c\u5909\u9769\u3059\u308b\u307e\u3067\u306e Kotlin \u306e\u5c0e\u5165\u7d4c\u7def\u3092\u8ffd\u3063\u305f\u300c<\/em><strong><em>Java \u4e3b\u4f53\u306e\u74b0\u5883\u3067 Kotlin \u306e\u5c0e\u5165\u3092\u6210\u529f\u3055\u305b\u308b\u305f\u3081\u306e\u7a76\u6975\u30ac\u30a4\u30c9<\/em><\/strong><em>\u300d\u9023\u8f09\u8a18\u4e8b\u306e\u7b2c 1 \u56de\u3067\u3059\u3002<\/em><\/p>\n<hr class=\"wp-block-separator has-alpha-channel-opacity\" \/>\n<p class=\"has-text-align-left\">\u300c\u30b9\u30a4\u30c3\u30c1\u3092\u62bc\u305b\u3070 Kotlin \u306b\u79fb\u884c\u3067\u304d\u308b\u308f\u3051\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002<\/p>\n<p class=\"has-text-align-left\"><em>\u30ea\u30b9\u30af\u3092\u6392\u9664\u3057\u3001\u8a55\u4fa1\u3057\u3001\u6210\u529f\u3092\u795d\u3044\u3001<\/em><\/p>\n<p class=\"has-text-align-left\"><em>\u305d\u306e\u4e0a\u3067\u3088\u3046\u3084\u304f Kotlin \u306e\u5c0e\u5165\u3092\u63a8\u9032\u3067\u304d\u308b\u306e\u3067\u3059\u3002<\/em>\u300d<\/p>\n<p>\u78ba\u7acb\u3057\u305f Java \u74b0\u5883\u306b Kotlin \u3092\u5c0e\u5165\u3059\u308b\u306b\u306f\u3001\u6280\u8853\u7684\u306a\u610f\u601d\u6c7a\u5b9a\u306e\u307f\u306a\u3089\u305a\u3001\u614e\u91cd\u306a\u8a08\u753b\u3001\u6226\u7565\u7684\u306a\u601d\u8003\u3001\u305d\u3057\u3066\u4f55\u3088\u308a\u3082\u5468\u56f2\u306e\u5fc3\u3068\u652f\u6301\u3092\u52dd\u3061\u53d6\u308b\u3053\u3068\u304c\u8981\u6c42\u3055\u308c\u307e\u3059\u3002<\/p>\n<p>\u79c1\u306f 1,000 \u4eba\u4ee5\u4e0a\u306e\u958b\u767a\u8005\u3092\u30c8\u30ec\u30fc\u30cb\u30f3\u30b0\u3057\u3001\u6570\u591a\u304f\u306e\u7d44\u7e54\u304c Kotlin \u306b\u79fb\u884c\u3059\u308b\u306e\u3092\u652f\u63f4\u3057\u306a\u304c\u3089\u3001\u52b9\u679c\u7684\u306a\u3082\u306e\u3068\u305d\u3046\u3067\u306a\u3044\u3082\u306e\u3092\u898b\u3066\u304d\u307e\u3057\u305f\u3002 \u3053\u306e\u30ac\u30a4\u30c9\u3067\u306f\u3001\u6700\u521d\u306e\u5b9f\u9a13\u7684\u306a\u30d7\u30ec\u30a4\u30b0\u30e9\u30a6\u30f3\u30c9\u304b\u3089\u5927\u898f\u6a21\u306a\u7d44\u7e54\u7684\u306a\u5909\u9769\u306b\u81f3\u308b\u307e\u3067\u3001\u79c1\u304c\u3053\u308c\u307e\u3067\u96c6\u3081\u3066\u304d\u305f Kotlin \u306e\u5c0e\u5165\u3092\u6210\u529f\u3055\u305b\u308b\u305f\u3081\u306e\u30ec\u30b7\u30d4\u3092\u3054\u7d39\u4ecb\u3057\u307e\u3059\u3002<\/p>\n<p>\u3053\u306e\u9023\u8f09\u3067\u306f\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u5c0e\u5165\u904e\u7a0b\u3092\u5c55\u958b\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n<ul>\n<li><a href=\"#it-always-starts-with-a-spark,-initiated-by-you\" data-type=\"link\" data-id=\"https:\/\/blog.jetbrains.com\/#it-always-starts-with-a-spark,-initiated-by-you\">\u706b\u4ed8\u3051\u5f79\u306f\u3044\u3064\u3082\u81ea\u5206\u306e\u5fc3\u3067\u3059\uff01<\/a><\/li>\n<li><a href=\"#the-play-around-stage-start-small-\u2013-with-tests\">\u5b9f\u9a13\u6bb5\u968e: \u5c0f\u3055\u304f\u59cb\u3081\u3066\u30c6\u30b9\u30c8\u3059\u308b<\/a><\/li>\n<li>\u8a55\u4fa1\u6bb5\u968e: \u30d7\u30ec\u30a4\u30b0\u30e9\u30a6\u30f3\u30c9\u3067\u306e Kotlin \u3092\u8131\u5374<\/li>\n<li>\u5468\u77e5\u6d3b\u52d5: \u5468\u308a\u306e\u958b\u767a\u8005\u306e\u5fc3\u3068\u652f\u6301\u3092\u52dd\u3061\u53d6\u308b<\/li>\n<li>\u7d4c\u55b6\u9663\u306e\u8aac\u5f97: Kotlin \u306e\u30d3\u30b8\u30cd\u30b9\u30b1\u30fc\u30b9\u3092\u69cb\u7bc9\u3059\u308b<\/li>\n<li>\u5927\u898f\u6a21\u306a Kotlin \u306e\u5c0e\u5165\u3092\u5b9f\u73fe\u3059\u308b\u6210\u529f\u8981\u56e0<\/li>\n<li>Kotlin \u306b\u79fb\u884c\u3059\u308b\u304b\u3057\u306a\u3044\u304b: \u3069\u306e\u3088\u3046\u306a\u4f1a\u793e\u306b\u6210\u9577\u3057\u305f\u3044\u306e\u304b\uff1f<\/li>\n<\/ul>\n<h2 class=\"wp-block-heading\"><strong>\u706b\u4ed8\u3051\u5f79\u306f\u3044\u3064\u3082\u81ea\u5206\u306e\u5fc3\u3067\u3059\uff01<\/strong><\/h2>\n<figure class=\"wp-block-image size-full\"><img decoding=\"async\" loading=\"lazy\" class=\"wp-image-647072\" src=\"https:\/\/blog.jetbrains.com\/wp-content\/uploads\/2025\/10\/unnamed-12.png\" alt=\"\u706b\u4ed8\u3051\u5f79\u306f\u3044\u3064\u3082\u81ea\u5206\u306e\u5fc3\u3067\u3059\uff01\" width=\"1586\" height=\"526\" \/><\/figure>\n<p><em>\u308f\u3056\u308f\u3056 Kotlin \u306b\u5207\u308a\u66ff\u3048\u3088\u3046\u3068\u3059\u308b\u7406\u7531\u306f\u4f55\u3067\u3057\u3087\u3046\u304b\uff1f Java \u306e\u307e\u307e\u9032\u3081\u3066\u306f\u3044\u3051\u306a\u3044\u306e\u3067\u3057\u3087\u3046\u304b\uff1f\u00a0<\/em><\/p>\n<p>\u3053\u306e\u7b54\u3048\u306f\u591a\u6570\u306e\u8981\u56e0\u306b\u3088\u3063\u3066\u5909\u308f\u308a\u307e\u3059\u3002 \u30c7\u30fc\u30bf\u304b\u3089\u306f\u8907\u6570\u5206\u91ce\u3067\u306e Kotlin \u306e\u30e1\u30ea\u30c3\u30c8\u304c\u660e\u78ba\u306b\u793a\u3055\u308c\u3066\u3044\u308b\u4e00\u65b9\u3001\u610f\u601d\u6c7a\u5b9a\u306f\u7d14\u7c8b\u306b\u6280\u8853\u7684\u306b\u884c\u308f\u308c\u308b\u3082\u306e\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002 \u4e3b\u89b3\u7684\u306a\u8003\u3048\uff08\u300c\u3053\u306e\u8a00\u8a9e\u304c\u597d\u304d\u3060\u304b\u3089\u597d\u304d\u300d\uff09\u3084\u65b0\u3057\u3044\u3082\u306e\u306b\u5bfe\u3059\u308b\u61d0\u7591\u5fc3\u306f\u6982\u3057\u3066\u826f\u3044\u3082\u306e\u3067\u3042\u308a\u3001\u91cd\u8981\u306a\u5f79\u5272\u3092\u679c\u305f\u3057\u307e\u3059\u3002<\/p>\n<p>\u3057\u304b\u3057\u306a\u304c\u3089\u3001\u30d7\u30ed\u30b0\u30e9\u30df\u30f3\u30b0\u8a00\u8a9e\u306e\u9032\u5316\u306f\u958b\u767a\u8005\u306e\u597d\u307f\u3084\u30cb\u30fc\u30ba\u304c\u6642\u9593\u3068\u3068\u3082\u306b\u5909\u5316\u3059\u308b\u3053\u3068\u306e\u73fe\u308c\u3067\u3059\u3002 \u3068\u308a\u308f\u3051\u91cd\u8981\u306a\u306e\u306f\u3001\u3069\u306e\u65b0\u4e16\u4ee3\u306e\u8a00\u8a9e\u306b\u3082\uff08null\uff09\u5b89\u5168\u6027\u3001\u7c21\u6f54\u3067\u8efd\u91cf\u306a\u69cb\u6587\u3001\u7b2c\u4e00\u7d1a\u30aa\u30d6\u30b8\u30a7\u30af\u30c8\u3068\u3057\u3066\u306e\u95a2\u6570\u3001\u8c4a\u5bcc\u306a\u6a19\u6e96\u30e9\u30a4\u30d6\u30e9\u30ea\u3001\u975e\u540c\u671f\u306e\u4e26\u884c\u6027\u3001\u30de\u30eb\u30c1\u30d7\u30e9\u30c3\u30c8\u30d5\u30a9\u30fc\u30e0\u306e\u30b5\u30dd\u30fc\u30c8\u3001\u751f\u6210 AI \u5bfe\u5fdc\u306a\u3069\u3001\u958b\u767a\u8005\u3084\u7d44\u7e54\u306b\u6c7a\u5b9a\u7684\u306a\u512a\u4f4d\u6027\u3092\u4e0e\u3048\u308b\u65b0\u3057\u3044\u30d1\u30e9\u30c0\u30a4\u30e0\u304c\u7d44\u307f\u8fbc\u307e\u308c\u3066\u3044\u308b\u3053\u3068\u3067\u3059\u3002<\/p>\n<p>\u3053\u306e\u3088\u3046\u306a\u81ea\u7136\u306a\u9032\u5316\u304c\u306a\u3051\u308c\u3070\u3001\u79c1\u305f\u3061\u306f\u4eca\u3067\u3082 COBOL \u3084\u4ed6\u306e\u53e4\u5178\u7684\u306a\u8a00\u8a9e\u3067\u3059\u3079\u3066\u3092\u30b3\u30fc\u30c7\u30a3\u30f3\u30b0\u3057\u3066\u304a\u308a\u3001\u4eca\u65e5\u306e\u8981\u6c42\u3092\u6e80\u305f\u305b\u3066\u3044\u306a\u304b\u3063\u305f\u3053\u3068\u3067\u3057\u3087\u3046\u3002 \u3064\u307e\u308a\u3001\u9032\u5316\u3068\u306f\u597d\u307f\u3067\u9078\u3079\u308b\u3082\u306e\u3067\u306f\u306a\u304f\u3001\u3053\u306e\u696d\u754c\u306e\u6b74\u53f2\u306b\u7d44\u307f\u8fbc\u307e\u308c\u3066\u3044\u308b\u3082\u306e\u306a\u306e\u3067\u3059\u3002<\/p>\n<p>\u305f\u3060\u3057\u3001\u3053\u306e\u3088\u3046\u306a\u9032\u5316\u304c\u793e\u5185\u306b\u6839\u4ed8\u304f\u306b\u306f\u3001\u6280\u8853\u7684\u306a\u30e1\u30ea\u30c3\u30c8\u3060\u3051\u3067\u306f\u4e0d\u5341\u5206\u3067\u3059\u3002 \u3053\u306e\u3088\u3046\u306a\u65b0\u3057\u3044\u30d1\u30e9\u30c0\u30a4\u30e0\u306e\u4fa1\u5024\u3092\u5b9f\u969b\u306b\u63a2\u6c42\u3057\u3001\u63d0\u5531\u3057\u3001\u793a\u3059\u610f\u6b32\u306e\u3042\u308b\u5b9f\u73fe\u8005\u304c\u5fc5\u8981\u3067\u3059\u3002 \u79c1\u306e\u7d4c\u9a13\u3067\u306f\u3001Kotlin \u306e\u5c0e\u5165\u3067\u30ab\u30bf\u30ea\u30b9\u30c8\u306b\u306a\u308c\u308b\u5178\u578b\u7684\u306a\u30a8\u30f3\u30b8\u30cb\u30a2\u306b\u306f\u4ee5\u4e0b\u306e 3 \u3064\u306e\u30bf\u30a4\u30d7\u304c\u3044\u307e\u3059\u3002<\/p>\n<ol>\n<li><strong>\u73fe\u5b9f\u7684\u3067\u751f\u7523\u6027\u3092\u91cd\u8996\u3059\u308b Java \u30a8\u30f3\u30b8\u30cb\u30a2<\/strong>: Java \u3092\u4fe1\u4ef0\u306e\u5bfe\u8c61\u3067\u306f\u306a\u304f\u3001\u30c4\u30fc\u30eb\u3068\u898b\u306a\u3057\u3066\u3044\u308b\u7d4c\u9a13\u8c4a\u5bcc\u306a\u958b\u767a\u8005\u3002 \u3053\u306e\u3088\u3046\u306a\u30a8\u30f3\u30b8\u30cb\u30a2\u306f\u5e38\u306b\u3088\u308a\u826f\u3044\u65b9\u6cd5\u3092\u8ffd\u6c42\u3057\u3001\u4f5c\u696d\u3092\u3088\u308a\u65e9\u304f\u5b8c\u4e86\u3055\u305b\u3088\u3046\u3068\u3057\u307e\u3059\u3002<\/li>\n<li><strong>\u54c1\u8cea\u5fd7\u5411\u306e\u30e2\u30c0\u30f3\u8a00\u8a9e\u611b\u597d\u5bb6<\/strong>: \u53ef\u8aad\u6027\u306b\u512a\u308c\u3001\u7c21\u6f54\u3067\u4fdd\u5b88\u3057\u3084\u3059\u3044\u30b3\u30fc\u30c9\u3092\u512a\u5148\u3059\u308b\u30a8\u30f3\u30b8\u30cb\u30a2\u3002 \u3053\u306e\u3088\u3046\u306a\u30a8\u30f3\u30b8\u30cb\u30a2\u306f\u591a\u304f\u306e\u5834\u5408\u3001\u904e\u53bb\u306b Scala \u306b\u79fb\u884c\u3057\u305f\u7d4c\u9a13\u304c\u3042\u308b\u30a8\u30f3\u30b8\u30cb\u30a2\u3067\u3082\u3042\u308a\u307e\u3059\u3002<\/li>\n<li><strong>\u30b8\u30e5\u30cb\u30a2\u958b\u767a\u8005<\/strong>: \u300cKotlin \u3092\u4f7f\u7528\u3067\u304d\u308b\u306e\u306b Java \u3092\u4f7f\u7528\u3059\u308b\u7406\u7531\u304c\u3042\u308b\u306e\u3060\u308d\u3046\u304b\uff1f\u300d\u306e\u3088\u3046\u306a\u5358\u7d14\u306a\u304c\u3089\u3082\u5f37\u70c8\u306a\u7591\u554f\u3092\u62b1\u304f\u30b8\u30e5\u30cb\u30a2\u958b\u767a\u8005\u3002 \u9577\u5e74\u306b\u308f\u305f\u3063\u3066 Java \u306b\u56fa\u57f7\u3057\u305f\u7d4c\u9a13\u3092\u6301\u305f\u306a\u3044\u30b8\u30e5\u30cb\u30a2\u958b\u767a\u8005\u306b\u3068\u3063\u3066\u3001Kotlin \u306f\u5f80\u3005\u306b\u3057\u3066\u5f53\u7136\u306e\u9078\u629e\u80a2\u306b\u306a\u308a\u307e\u3059\u3002<\/li>\n<\/ol>\n<p>\u3042\u306a\u305f\u306f\u3069\u306e\u30a8\u30f3\u30b8\u30cb\u30a2\u3067\u3059\u304b\uff1f<\/p>\n<p>\u3053\u306e\u3088\u3046\u306a\u65e9\u671f\u63a1\u7528\u8005\u306f\u3001\u6700\u521d\u306e\u6bb5\u968e\u306e\u706b\u4ed8\u3051\u5f79\u306b\u306a\u308a\u307e\u3059\u3002 \u3057\u304b\u3057\u3001\u3069\u306e\u3088\u3046\u306b\u59cb\u3081\u308c\u3070\u3088\u3044\u306e\u3067\u3057\u3087\u3046\u304b\uff1f \u7d9a\u304d\u3092\u8aad\u3093\u3067\u304f\u3060\u3055\u3044\u2026 ;-)<\/p>\n<h2 class=\"wp-block-heading\"><strong>\u5b9f\u9a13\u6bb5\u968e: \u5c0f\u3055\u304f\u59cb\u3081\u3066\u30c6\u30b9\u30c8\u3059\u308b<\/strong><\/h2>\n<p>Kotlin \u306b\u3064\u3044\u3066\u805e\u3044\u305f\u3053\u3068\u304c\u3042\u308b\u65b9\u306f\u3001\u3059\u3050\u306b\u6c7a\u65ad\u305b\u305a\u306b\u8a66\u3057\u3066\u307f\u305f\u3044\u3068\u601d\u3063\u3066\u3044\u308b\u306f\u305a\u3067\u3059\u3002<\/p>\n<p>\u6700\u521d\u306b\u5fc5\u8981\u3068\u306a\u308b\u306e\u306f\u3001\u6700\u521d\u306e Kotlin \u306e\u7a2e\u3092\u307e\u304f\u3053\u3068\u304c\u3067\u304d\u308b\u958b\u767a\u8005\u30c4\u30fc\u30eb\u3067\u3059\u3002 \u4ee5\u4e0b\u306e\u3088\u3046\u306a\u9078\u629e\u80a2\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<ul>\n<li><a href=\"https:\/\/play.kotlinlang.org\/\" target=\"_blank\" rel=\"noreferrer noopener\">https:\/\/play.kotlinlang.org\/<\/a> \u306f\u512a\u308c\u305f\u30aa\u30f3\u30e9\u30a4\u30f3\u30d7\u30ec\u30a4\u30b0\u30e9\u30a6\u30f3\u30c9\u3067\u3059\u3002JVM \u306e\u307f\u306a\u3089\u305a\u3001\u4ed6\u306e\u5404\u7a2e\u30d7\u30e9\u30c3\u30c8\u30d5\u30a9\u30fc\u30e0\uff08JS \u3084 WASM \u306a\u3069\uff09\u5411\u3051\u306e Kotlin \u30b3\u30fc\u30c9\u3092\u7c21\u5358\u306b\u5165\u529b\u3057\u3066\u5b9f\u884c\u3067\u304d\u307e\u3059\u3002<img decoding=\"async\" loading=\"lazy\" class=\"wp-image-647084\" style=\"width: 650px;\" src=\"https:\/\/blog.jetbrains.com\/wp-content\/uploads\/2025\/10\/unnamed-13.png\" alt=\"Kotlin\u30d7\u30ec\u30a4\u30b0\u30e9\u30a6\u30f3\u30c9\" width=\"1462\" height=\"660\" \/><\/li>\n<\/ul>\n<ul>\n<li><a href=\"https:\/\/kotlinlang.org\/docs\/kotlin-notebook-overview.html\" target=\"_blank\" rel=\"noreferrer noopener\">Kotlin Notebook<\/a> \u306f IntelliJ IDEA \u7528\u306e\u5f37\u529b\u306a\u6a5f\u80fd\u3067\u3059\u3002\u4f9d\u5b58\u95a2\u4fc2\u306e\u30a4\u30f3\u30dd\u30fc\u30c8\u3001\u30b3\u30fc\u30c9\u306e\u5b9f\u884c\u3001\u3055\u3089\u306b\u306f\u30c7\u30fc\u30bf\u306e\u64cd\u4f5c\u3084\u30b0\u30e9\u30d5\u306e\u751f\u6210\u306a\u3069\u3092\u7c21\u5358\u306b\u884c\u3048\u307e\u3059\u3002 \u4ee5\u4e0b\u306e\u4f8b\u3067\u306f\u3001Spring \u306e RestClient \u3067 REST \u547c\u3073\u51fa\u3057\u3092\u7c21\u5358\u306b\u884c\u3048\u308b\u3053\u3068\u304c\u5206\u304b\u308a\u307e\u3059\u3002<img decoding=\"async\" loading=\"lazy\" class=\"wp-image-647095\" style=\"width: 650px;\" src=\"https:\/\/blog.jetbrains.com\/wp-content\/uploads\/2025\/10\/unnamed-11.png\" alt=\"Kotlin Notebook\" width=\"1600\" height=\"1035\" \/><\/li>\n<\/ul>\n<ul>\n<li>IntelliJ IDEA \u306b\u306f \u6700\u9ad8\u6c34\u6e96\u306e Kotlin \u306e\u30b5\u30dd\u30fc\u30c8\u304c\u5099\u308f\u3063\u3066\u3044\u307e\u3059\u3002 JetBrains \u306f Kotlin \u306e\u4f5c\u6210\u5143\u3067\u3042\u308a\u3001IntelliJ IDEA \u306e\u5927\u90e8\u5206\u304c Kotlin \u3067\u66f8\u304b\u308c\u3066\u3044\u308b\u305f\u3081\u3001\u3053\u308c\u306f\u9a5a\u304f\u3053\u3068\u3067\u306f\u3042\u308a\u307e\u305b\u3093\u3002 \u305d\u306e\u305f\u3081\u3001<a href=\"https:\/\/www.jetbrains.com\/help\/idea\/get-started-with-kotlin.html#add-kotlin-dependency\" target=\"_blank\" rel=\"noreferrer noopener\">IntelliJ IDEA<\/a> \u3067\u306f\u65e2\u5b58\u306e Java \u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3067\u3082\u7c21\u5358\u306b Kotlin \u306e\u4f7f\u7528\u3092\u958b\u59cb\u3067\u304d\u307e\u3059\u3002\n<ul>\n<li><a href=\"https:\/\/kotlinlang.org\/docs\/maven.html\" target=\"_blank\" rel=\"noreferrer noopener\">Maven<\/a> \u306e\u5834\u5408\u306f\u3001<code>kotlin-maven-plugin<\/code> \u3068 Kotlin \u6a19\u6e96\u30e9\u30a4\u30d6\u30e9\u30ea\u306e <code>kotlin-stdlib<\/code> \u3092\u69cb\u6210\u3059\u308b\u3060\u3051\u3067\u3059\u3002<\/li>\n<li><a href=\"https:\/\/kotlinlang.org\/docs\/gradle-configure-project.html\" target=\"_blank\" rel=\"noreferrer noopener\">Gradle<\/a> \u306e\u5834\u5408\u306f\u3001kotlin \u30d7\u30e9\u30b0\u30a4\u30f3\u3092\u69cb\u6210\u3057\u307e\u3059\u3002<\/li>\n<\/ul>\n<\/li>\n<\/ul>\n<p>\u2026\u3059\u308b\u3068\u3001\u3053\u3046\u306a\u308a\u307e\u3059\uff01<\/p>\n<figure class=\"wp-block-image size-full is-resized\"><img decoding=\"async\" loading=\"lazy\" class=\"wp-image-647106\" style=\"aspect-ratio: 1.1216216216216217; width: 320px; height: auto;\" src=\"https:\/\/blog.jetbrains.com\/wp-content\/uploads\/2025\/10\/unnamed-14.png\" alt=\"\" width=\"498\" height=\"444\" \/><\/figure>\n<ul>\n<li>\u4ed6\u306b\u3082\u307e\u3060\u307e\u3060\u3042\u308a\u307e\u3059\uff01 JetBrains \u306f Kotlin Language Server \u3092\u6700\u8fd1\u30ea\u30ea\u30fc\u30b9\u3057\u3001\u30d5\u30eb\u6a5f\u80fd\u3092\u4f7f\u7528\u3057\u305f Kotlin \u958b\u767a\u3092 IntelliJ IDEA \u4ee5\u5916\u306e\u4ed6\u306e IDE\uff08VS Code \u306a\u3069\uff09\u3067\u3082\u4f53\u9a13\u3067\u304d\u308b\u3088\u3046\u306b\u3057\u307e\u3057\u305f\u3002 \u3053\u3061\u3089\u3092\u3054\u89a7\u304f\u3060\u3055\u3044: <a href=\"https:\/\/github.com\/Kotlin\/kotlin-lsp\" target=\"_blank\" rel=\"noreferrer noopener\">https:\/\/github.com\/Kotlin\/kotlin-lsp<\/a><\/li>\n<\/ul>\n<p>\u3053\u308c\u3067\u304a\u6c17\u306b\u5165\u308a\u306e\u958b\u767a\u74b0\u5883\u3067 Kotlin \u3092\u66f8\u3051\u308b\u3088\u3046\u306b\u306a\u308a\u307e\u3057\u305f\u3002 \u5b9f\u969b\u306b\u306f\u3069\u306e\u3088\u3046\u306b\u3053\u306e\u8a00\u8a9e\u3092\u8a55\u4fa1\u3057\u3001\u5f71\u97ff\u3092\u6700\u5c0f\u9650\u306b\u6291\u3048\u306a\u304c\u3089\u6700\u5927\u9650\u306e\u30a4\u30f3\u30b5\u30a4\u30c8\u3092\u5f97\u308b\u3053\u3068\u304c\u3067\u304d\u308b\u306e\u3067\u3057\u3087\u3046\u304b\uff1f \u305d\u306e\u305f\u3081\u306b\u306f\u65e2\u5b58\u306e Java \u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u306e\u30c6\u30b9\u30c8\u30b9\u30a4\u30fc\u30c8\u3092\u4f7f\u7528\u3057\u307e\u3059\uff01<\/p>\n<p>\u3053\u306e\u5b89\u5168\u3067\u73fe\u5b9f\u7684\u306a\u65b9\u6cd5\u3067 Kotlin \u3092\u5b9f\u9a13\u3059\u308b\u3053\u3068\u306b\u306f\u3001\u4ee5\u4e0b\u306e\u3044\u304f\u3064\u304b\u306e\u30e1\u30ea\u30c3\u30c8\u304c\u3042\u308a\u307e\u3059\u3002<\/p>\n<ul>\n<li><strong>\u4f4e\u30ea\u30b9\u30af<\/strong>: \u30c6\u30b9\u30c8\u304c\u672c\u756a\u74b0\u5883\u30b3\u30fc\u30c9\u306b\u5f71\u97ff\u3059\u308b\u3053\u3068\u306f\u3042\u308a\u307e\u305b\u3093\u3002<\/li>\n<li><strong>\u5b66\u7fd2\u306e\u6a5f\u4f1a<\/strong>: \u4f7f\u3044\u6163\u308c\u305f\u74b0\u5883\u3067\u8a00\u8a9e\u306e\u6a5f\u80fd\u3092\u8a66\u3059\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/li>\n<li><strong>\u6bb5\u968e\u7684\u306a\u5c0e\u5165<\/strong>: \u30c1\u30fc\u30e0\u30e1\u30f3\u30d0\u30fc\u306f\u30d7\u30ec\u30c3\u30b7\u30e3\u30fc\u3092\u611f\u3058\u308b\u3053\u3068\u306a\u304f\u3001Kotlin \u306e\u69cb\u6587\u306b\u6163\u308c\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/li>\n<\/ul>\n<h3 class=\"wp-block-heading\"><strong>\u30d2\u30f3\u30c8<\/strong><\/h3>\n<ol>\n<li>Kotest + MockK \u3092\u8a66\u3057\u307e\u3057\u3087\u3046\u3002\u6a5f\u80fd\u8c4a\u5bcc\u306a\u30a2\u30b5\u30fc\u30b7\u30e7\u30f3\uff08<code>shouldHaveSize(...)<\/code>\uff09\u3084\u63a5\u4e2d\u8f9e\uff08<code>value shouldBe 1<\/code>\uff09\u306a\u3069\u3001Kotlin \u306e\u30c6\u30b9\u30c8 DSL\uff08\u30c9\u30e1\u30a4\u30f3\u56fa\u6709\u8a00\u8a9e\uff09\u306e\u8868\u73fe\u529b\u3092\u3059\u3050\u306b\u611f\u3058\u53d6\u308b\u3053\u3068\u304c\u3067\u304d\u307e\u3059\u3002<\/li>\n<li>Java \u306e\u30b9\u30c8\u30ea\u30fc\u30e0\u3067\u306f\u306a\u304f\u3001\u7c21\u6f54\u3067\u5f37\u529b\u306a Kotlin \u306e\u30b3\u30ec\u30af\u30b7\u30e7\u30f3\u3092\u4f7f\u7528\u3057\u307e\u3057\u3087\u3046\u3002<\/li>\n<li>null \u8a31\u5bb9\u578b\u3001\u975e\u69cb\u9020\u5316\u3001\u4e0d\u5909\u6027\uff08<code>val<\/code>\u3001<code>data classes<\/code>\uff09\u3001\u5f0f\u30b3\u30f3\u30b9\u30c8\u30e9\u30af\u30c8\uff08<code>when<\/code>\u3001<code>try-catch<\/code>\u3001<code>if else<\/code>\uff09\u306a\u3069\u306e\u3055\u307e\u3056\u307e\u306a\u8a00\u8a9e\u6a5f\u80fd\u3092\u8a66\u3057\u3066\u307f\u307e\u3057\u3087\u3046\u3002<\/li>\n<\/ol>\n<p>\u4ee5\u4e0b\u306e\u3088\u3046\u306b\u306a\u308a\u307e\u3059\u3002<\/p>\n<p><strong>Java<\/strong><\/p>\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"java\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Test\nvoid shouldGetAverageRating() {\n   when(productRepository.findAll()).thenReturn(products);\n\n   Map&lt;String, Double&gt; ratings = productService.averageRatings();\n\n   assertAll(\n           () -&gt; assertThat(ratings).hasSize(4),\n           () -&gt; assertEquals(ratings, products\n                   .stream()\n                   .collect(Collectors.groupingBy(\n                           Product::getName,\n                           Collectors.flatMapping(\n                                   p -&gt; p.getRatings()\n                                    .stream()\n                                    .mapToDouble(Integer::doubleValue)\n                                    .boxed(),   \n                              Collectors.averagingDouble(Double::doubleValue)\n                           )))\n           )\n   );\n   verify(productRepository).findAll();\n\n}\n<\/pre>\n<p><strong>Kotlin<\/strong><\/p>\n<pre class=\"EnlighterJSRAW\" data-enlighter-language=\"kotlin\" data-enlighter-theme=\"\" data-enlighter-highlight=\"\" data-enlighter-linenumbers=\"\" data-enlighter-lineoffset=\"\" data-enlighter-title=\"\" data-enlighter-group=\"\">@Test\nfun `should get average rating`() { \/\/descriptive tests using ``\n   every { productRepository.findAll() } returns products\n\n   val ratings = productService.averageRatings()\n\n   assertSoftly(ratings) { \t\t\/\/powerful testing DSLs (Kotest)\n       shouldHaveSize(4)\n       this shouldBe productRepository.findAll()\n           .groupBy { it.name }   \t\t\t\/\/concise collections\n           .mapValues { (_, products) -&gt; \t\t\/\/destructuring\n                  products.flatMap { it.ratings }.average() }\n   }\n    verify { productRepository.findAll() }\n}<\/pre>\n<h3 class=\"wp-block-heading\">\u3053\u306e\u9023\u8f09\u306e\u6b21\u306e\u8a18\u4e8b<\/h3>\n<p>Kotlin \u306e\u5c0e\u5165\u306f\u4e00\u822c\u7684\u306b 1 \u4eba\u306e\u958b\u767a\u8005\u306e\u63a2\u7a76\u306b\u59cb\u307e\u308a\u3001\u3044\u304f\u3064\u304b\u306e\u30c6\u30b9\u30c8\u306b\u3088\u3063\u3066\u305d\u306e\u6709\u7528\u6027\u304c\u8a3c\u660e\u3055\u308c\u307e\u3059\u3002 \u3053\u306e\u3088\u3046\u306a\u6700\u521d\u306e\u767a\u898b\u306f\u3001\u5fc5\u7136\u7684\u306b\u5b9f\u969b\u306e\u30d7\u30ed\u30b8\u30a7\u30af\u30c8\u3067\u306e Kotlin \u306e\u8a55\u4fa1\u3068\u3044\u3046\u5927\u304c\u304b\u308a\u306a\u53d6\u308a\u7d44\u307f\u306b\u3064\u306a\u304c\u3063\u3066\u3044\u304d\u307e\u3059\u3002<\/p>\n<p>\u3053\u306e\u9023\u8f09\u306e\u6b21\u306e\u8a18\u4e8b\u3067\u306f\u3001\u305d\u306e\u6bb5\u968e\u3068\u672c\u756a\u74b0\u5883\u3067\u306e Kotlin \u306e\u30c6\u30b9\u30c8\u65b9\u6cd5\u306b\u3064\u3044\u3066\u8aac\u660e\u3057\u307e\u3059\u3002<\/p>\n<p><strong>\u30aa\u30ea\u30b8\u30ca\u30eb\uff08\u82f1\u8a9e\uff09\u30d6\u30ed\u30b0\u6295\u7a3f\u8a18\u4e8b\u306e\u4f5c\u8005\uff1a<\/strong><\/p>\n<div class=\"about-author \">\n<div class=\"about-author__box\">\n<div class=\"row\">\n<div class=\"about-author__box-img\"><img decoding=\"async\" src=\"https:\/\/blog.jetbrains.com\/wp-content\/uploads\/2025\/10\/a3f7-400o400o1-QYUavRYyARnAVJLCpM1m8M.webp\" alt=\"\" \/><\/div>\n<div class=\"about-author__box-text\">\n<h4>Urs Peter<\/h4>\n<p>Urs \u306f\u7d4c\u9a13\u8c4a\u5bcc\u306a\u30bd\u30d5\u30c8\u30a6\u30a7\u30a2\u30a8\u30f3\u30b8\u30cb\u30a2\u3001\u30bd\u30ea\u30e5\u30fc\u30b7\u30e7\u30f3\u30a2\u30fc\u30ad\u30c6\u30af\u30c8\u3001\u30ab\u30f3\u30d5\u30a1\u30ec\u30f3\u30b9\u8b1b\u6f14\u8005\u3001\u30c8\u30ec\u30fc\u30ca\u30fc\u3067\u3042\u308a\u3001\u4e3b\u306b Kotlin \u3068 Scala \u304c\u95a2\u308f\u308b\u30ec\u30b8\u30ea\u30a8\u30f3\u30c8\u3067\u62e1\u5f35\u53ef\u80fd\u3001\u304b\u3064\u30df\u30c3\u30b7\u30e7\u30f3\u30af\u30ea\u30c6\u30a3\u30ab\u30eb\u306a\u30b7\u30b9\u30c6\u30e0\u306e\u69cb\u7bc9\u306b 20 \u5e74\u4ee5\u4e0a\u643a\u308f\u3063\u3066\u304d\u307e\u3057\u305f\u3002<\/p>\n<p>\u30b3\u30f3\u30b5\u30eb\u30bf\u30f3\u30c8\u696d\u306e\u508d\u3089\u3001Kotlin \u3068 Scala \u306e\u8a00\u8a9e\u30b3\u30fc\u30b9\u304b\u3089\u30de\u30a4\u30af\u30ed\u30b5\u30fc\u30d3\u30b9\u3084\u30a4\u30d9\u30f3\u30c8\u99c6\u52d5\u578b\u30a2\u30fc\u30ad\u30c6\u30af\u30c1\u30e3\u3068\u3044\u3063\u305f\u30a2\u30fc\u30ad\u30c6\u30af\u30c1\u30e3\u95a2\u9023\u30c8\u30ec\u30fc\u30cb\u30f3\u30b0\u306b\u81f3\u308b\u591a\u7a2e\u591a\u69d8\u306a\u30b3\u30fc\u30b9\u306e\u30c8\u30ec\u30fc\u30ca\u30fc\u3068\u4f5c\u6210\u8005\u3068\u3057\u3066\u3082\u60c5\u71b1\u7684\u306b\u6d3b\u52d5\u3057\u3066\u3044\u307e\u3059\u3002<\/p>\n<p>\u5143\u3005\u4eba\u3068\u306e\u4ea4\u6d41\u3092\u597d\u3080\u6027\u683c\u3067\u3042\u308a\u3001\u30df\u30fc\u30c8\u30a2\u30c3\u30d7\u3084\u30ab\u30f3\u30d5\u30a1\u30ec\u30f3\u30b9\u3067\u4ed6\u306e\u958b\u767a\u8005\u3068\u77e5\u8b58\u3092\u5171\u6709\u3057\u3001\u523a\u6fc0\u3057\u5408\u3046\u3053\u3068\u3092\u697d\u3057\u3093\u3067\u3044\u307e\u3059\u3002 Urs \u306f JetBrains \u8a8d\u5b9a Kotlin \u30c8\u30ec\u30fc\u30ca\u30fc\u3067\u3059\u3002<\/p>\n<\/div>\n<\/div>\n<\/div>\n<\/div>\n\n    <div class=\"about-author \">\n        <div class=\"about-author__box\">\n            <div class=\"row\">\n                <div class=\"about-author__box-img\">\n                    <img decoding=\"async\" src=\"https:\/\/blog.jetbrains.com\/wp-content\/uploads\/2021\/08\/photo_2021-08-03_15-27-43-200x200.jpg\" width=\"200\" height=\"200\" alt=\"Alyona Chernyaeva\" loading=\"lazy\"  class=\"avatar avatar-200 wp-user-avatar wp-user-avatar-200 photo avatar-default\">\n                <\/div>\n                <div class=\"about-author__box-text\">\n                                            <h4>Alyona Chernyaeva<\/h4>\n                                                        <\/div>\n            <\/div>\n        <\/div>\n    <\/div>\n","protected":false},"author":1394,"featured_media":672623,"comment_status":"closed","ping_status":"closed","template":"","categories":[],"tags":[],"cross-post-tag":[],"acf":[],"_links":{"self":[{"href":"https:\/\/blog.jetbrains.com\/ja\/wp-json\/wp\/v2\/kotlin\/670651"}],"collection":[{"href":"https:\/\/blog.jetbrains.com\/ja\/wp-json\/wp\/v2\/kotlin"}],"about":[{"href":"https:\/\/blog.jetbrains.com\/ja\/wp-json\/wp\/v2\/types\/kotlin"}],"author":[{"embeddable":true,"href":"https:\/\/blog.jetbrains.com\/ja\/wp-json\/wp\/v2\/users\/1394"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.jetbrains.com\/ja\/wp-json\/wp\/v2\/comments?post=670651"}],"version-history":[{"count":6,"href":"https:\/\/blog.jetbrains.com\/ja\/wp-json\/wp\/v2\/kotlin\/670651\/revisions"}],"predecessor-version":[{"id":672646,"href":"https:\/\/blog.jetbrains.com\/ja\/wp-json\/wp\/v2\/kotlin\/670651\/revisions\/672646"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/blog.jetbrains.com\/ja\/wp-json\/wp\/v2\/media\/672623"}],"wp:attachment":[{"href":"https:\/\/blog.jetbrains.com\/ja\/wp-json\/wp\/v2\/media?parent=670651"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.jetbrains.com\/ja\/wp-json\/wp\/v2\/categories?post=670651"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.jetbrains.com\/ja\/wp-json\/wp\/v2\/tags?post=670651"},{"taxonomy":"cross-post-tag","embeddable":true,"href":"https:\/\/blog.jetbrains.com\/ja\/wp-json\/wp\/v2\/cross-post-tag?post=670651"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}