{"id":34530,"date":"2020-05-18T16:34:07","date_gmt":"2020-05-18T08:34:07","guid":{"rendered":"https:\/\/blog.jetbrains.com\/cn\/?p=879"},"modified":"2020-07-01T13:11:20","modified_gmt":"2020-07-01T13:11:20","slug":"eap-kotlin-1-4-m2","status":"publish","type":"post","link":"https:\/\/blog.jetbrains.com\/zh-hans\/2020\/05\/18\/eap-kotlin-1-4-m2\/","title":{"rendered":"\u62a2\u5148\u4f53\u9a8c Kotlin 1.4-M2\uff1a\u6807\u51c6\u5e93\u6539\u8fdb"},"content":{"rendered":"\u6211\u4eec\u5df2\u51c6\u5907\u597d\u5728\u6b64\u9884\u89c8\u7248\u4e2d\u5f15\u5165\u4e00\u4e9b\u6539\u8fdb\uff1b\u5728\u8fd9\u7bc7\u535a\u6587\u4e2d\uff0c\u6211\u4eec\u5c06\u4ecb\u7ecd\u6807\u51c6\u5e93\u7684\u53d8\u5316\u3002\r\n\r\n\u4ee5\u4e0b\u662f 1.4-M2 \u4e2d\u6807\u51c6\u5e93\u7684\u4e00\u4e9b\u4e3b\u8981\u6539\u8fdb\uff1a\r\n\r\n\r\n\t\u73b0\u6709 API \u7684\u53d8\u5316\uff0c\u4f8b\u5982\u66f4\u65b0\u7b7e\u540d\u548c\u5f15\u5165\u65b0\u5e38\u91cf\r\n\t\u901a\u7528\u5e93\u4e2d\u63d0\u4f9b\u66f4\u591a\u51fd\u6570\r\n\t\u4e3a\u6570\u7ec4\u4e0e\u96c6\u5408\u6dfb\u52a0\u65b0\u51fd\u6570\r\n\t\u5c5e\u6027\u59d4\u6258\u6539\u8fdb\r\n\r\n\r\n\u5c3d\u7ba1 Kotlin 1.4-M2 \u5c1a\u672a\u53d1\u5e03\uff0c\u4f46\u6211\u4eec\u5df2\u5c06\u5176\u65e9\u671f\u7248\u672c\u90e8\u7f72\u5230\u00a0Kotlin \u6f14\u7ec3\u573a\u4e2d\uff0c\u60a8\u53ef\u4ee5\u5c1d\u8bd5\u672c\u6587\u4e2d\u4ecb\u7ecd\u7684\u6240\u6709\u529f\u80fd\u3002\u672c\u6587\u4e2d\u7684\u4ee3\u7801\u793a\u4f8b\u4e5f\u53ef\u4ee5\u5728\u65b0\u7248\u672c\u4e0a\u8fd0\u884c\u3002\r\n\r\n\u5982\u679c\u60a8\u8feb\u4e0d\u53ca\u5f85\u5730\u60f3\u8981\u4f53\u9a8c\u65b0\u5730\u7248\u672c\uff0c\u8ba2\u9605\u6211\u4eec\u7684 Kotlin \u535a\u5ba2\u65b0\u95fb\u901a\u8baf\uff0c\u4e0d\u5fc5\u62c5\u5fc3\u9519\u8fc7\u53d1\u5e03\u7684\u6d88\u606f\uff01\r\n\u6269\u5c55\u901a\u7528\u5e93\r\n\u60a8\u53ef\u4ee5\u5728\u201c\u901a\u7528\u201d\u4ee3\u7801\u4e2d\u4f7f\u7528\u6807\u51c6\u5e93\uff0c\u201c\u901a\u7528\u201d\u4ee3\u7801\u662f\u6307\u5728\u4e0d\u540c\u7684\u5e73\u53f0\uff08\u5373 Android \u4e0e iOS \u6216 JVM \u4e0e JS\uff09\u4e4b\u95f4\u5171\u4eab\u7684\u4ee3\u7801\u3002\u6211\u4eec\u5c06\u9010\u6b65\u6269\u5c55\u901a\u7528\u5e93\uff0c\u5e76\u5411\u5176\u6dfb\u52a0\u6216\u5f15\u5165\u7f3a\u5c11\u7684\u529f\u80fd\u3002\r\n\r\n\u4e4b\u524dappendln\u00a0\u5728 Kotlin\/JVM \u4e2d\u7684\u4e0a\u4e00\u4e2a\u5b9e\u73b0\u6dfb\u52a0\u4e86\u4e00\u4e2a\u56e0\u7cfb\u7edf\u800c\u5f02\u7684\u884c\u5206\u9694\u7b26\uff08UNIX \u7cfb\u7edf\u4e0a\u4e3a\u00a0\\n\uff1bWindows \u4e0a\u4e3a\u00a0\\r\\n\uff09\u3002\u4e0d\u8fc7\uff0c\u65e2\u7136\u662f\u901a\u7528\u4ee3\u7801\uff0c\u6211\u4eec\u8ba4\u4e3a\u65e0\u8bba\u64cd\u4f5c\u7cfb\u7edf\u548c\u5e95\u5c42\u5e73\u53f0\u5982\u4f55\uff0c\u786e\u4fdd\u4e00\u81f4\u7684\u884c\u4e3a\u975e\u5e38\u91cd\u8981\u3002\r\n\r\n\u56e0\u6b64\uff0c\u6211\u4eec\u5f03\u7528\u4e86\u00a0appendln\u00a0\u5e76\u91c7\u7528\u65b0\u7684\u00a0appendLine\u00a0\u51fd\u6570\uff0c\u540e\u8005\u59cb\u7ec8\u4f7f\u7528\u4e00\u4e2a\u00a0\\n\u00a0\u5b57\u7b26\u7ec8\u6b62\u884c\uff1a\r\n\r\n[kotlin version=\"1.4-M2-preview\"]\r\nfun main() {\r\n\/\/sampleStart\r\nprintln(buildString {\r\nappendLine(\"Hello,\")\r\nappendLine(\"Kotlin 1.4-M2\")\r\n})\r\n\/\/sampleEnd\r\n}\r\n[\/kotlin]\r\n\r\n\u5982\u679c\u60a8\u9700\u8981\u5e73\u53f0\u7279\u5b9a\u7684\u5206\u9694\u7b26\uff0c\u4ecd\u53ef\u4ee5\u5728 JVM \u4e2d\u4f7f\u7528\u00a0System.lineSeparator()\u3002\r\n\r\n\u73b0\u5728\u53ef\u4ee5\u5728\u901a\u7528\u4ee3\u7801\u4e2d\u4f7f\u7528\u7684\u5176\u4ed6\u51fd\u6570\u8ba9\u60a8\u80fd\u591f\u4f7f\u7528\u7ed9\u5b9a\u5806\u6808\u8ddf\u8e2a\u7684\u5b57\u7b26\u4e32\u8868\u793a\u3002Throwable.stackTraceToString()\u00a0\u6269\u5c55\u53ef\u4ee5\u8fd4\u56de\u6b64 Throwable \u53ca\u5176\u5806\u6808\u8ddf\u8e2a\u7684\u8be6\u7ec6\u8bf4\u660eThrowable.printStackTrace()\u00a0\u53ef\u4ee5\u5c06\u6b64\u8bf4\u660e\u6253\u5370\u5230\u6807\u51c6\u9519\u8bef\u8f93\u51fa\u3002\r\n\r\n\u5728\u901a\u7528\u4ee3\u7801\u4e2d\uff0c\u60a8\u8fd8\u53ef\u4ee5\u4f7f\u7528\u00a0Throwable.addSuppressed()\u00a0\u51fd\u6570\uff08\u8ba9\u60a8\u53ef\u4ee5\u6307\u5b9a\u4e4b\u524d\u88ab\u6291\u5236\u7684\u5f02\u5e38\u4ee5\u63d0\u4f9b\u5f02\u5e38\uff09\u548c\u00a0Throwable.suppressedExceptions\u00a0\u5c5e\u6027\uff08\u53ef\u4ee5\u8fd4\u56de\u6240\u6709\u88ab\u6291\u5236\u5f02\u5e38\u7684\u5217\u8868\uff09\u3002\r\n\u65b0\u7684\u6570\u7ec4\u51fd\u6570\r\n\u4e3a\u4e86\u5728\u5904\u7406\u4e0d\u540c\u7684\u5bb9\u5668\u7c7b\u578b\u65f6\u63d0\u4f9b\u4e00\u81f4\u7684\u4f53\u9a8c\uff0c\u6211\u4eec\u4e3a\u6570\u7ec4\u6dfb\u52a0\u4e86\u65b0\u7684\u6269\u5c55\u51fd\u6570\uff1a\r\n\r\n\r\n\tshuffle()\u00a0- \u4ee5\u968f\u673a\u987a\u5e8f\u653e\u7f6e\u6570\u7ec4\u5143\u7d20\u3002\r\n\t\r\nonEach()\u00a0- \u5728\u6bcf\u4e2a\u6570\u7ec4\u5143\u7d20\u4e0a\u6267\u884c\u7ed9\u5b9a\u64cd\u4f5c\u5e76\u8fd4\u56de\u6570\u7ec4\u672c\u8eab\u3002\r\n\r\n\r\n\u4f7f\u7528\u5217\u8868\u7684\u7528\u6237\u5e94\u5f53\u975e\u5e38\u719f\u6089\u8fd9\u4e9b\u51fd\u6570\uff1b\u5b83\u4eec\u4ee5\u76f8\u540c\u7684\u65b9\u5f0f\u9002\u7528\u4e8e\u6570\u7ec4\u3002\r\n\r\n[kotlin version=\"1.4-M2-preview\"]\r\nfun main() {\r\n\/\/sampleStart\r\nvar language = \"\"\r\nval letters = arrayOf(\"k\", \"o\", \"t\", \"l\", \"i\", \"n\")\r\nval fileExt = letters.onEach { language += it }\r\n.filterNot { it in \"aeuio\" }.take(2)\r\n.joinToString(prefix = \".\", separator = \"\")\r\nprintln(language) \/\/ \"kotlin\"\r\nprintln(fileExt) \/\/ \".kt\"\r\n\r\nletters.shuffle()\r\nprintln(letters.contentToString())\r\n\/\/sampleEnd\r\n}\r\n[\/kotlin]\r\n\r\n\u6211\u4eec\u8fd8\u6dfb\u52a0\u4e86\u7528\u4e8e\u5bf9\u6570\u7ec4\u5b50\u8303\u56f4\u8fdb\u884c\u6392\u5e8f\u7684\u65b0\u51fd\u6570\u3002\u4e4b\u524d\uff0c\u6709\u4e00\u4e2a\u5305\u542b\u00a0fromIndex\u00a0\u548c\u00a0toIndex\u00a0\u53c2\u6570\u7684\u00a0sort()\uff0c\u4f46\u5b83\u4ec5\u9002\u7528\u4e8e JVM\u3002\u73b0\u5728\uff0c\u5b83\u5728\u5404\u4e2a\u5e73\u53f0\u4e0a\u90fd\u901a\u7528\uff0c\u8fd8\u6709\u4e24\u4e2a\u65b0\u7684\u76f8\u5173\u51fd\u6570\uff0c\u5b83\u4eec\u662f\u5b50\u8303\u56f4\u7248\u672c\u7684\u00a0reverse()\u00a0\u548c\u00a0sortDescending()\u3002\u6bcf\u4e00\u4e2a\u90fd\u9700\u8981\u4e24\u4e2a\u7d22\u5f15\uff0c\u5e76\u4ee5\u4ece\u540d\u79f0\u5373\u53ef\u770b\u51fa\u7684\u65b9\u5f0f\u5728\u5b83\u4eec\u4e4b\u95f4\u91cd\u65b0\u6392\u5e8f\u5143\u7d20\uff08\u5305\u62ec\u00a0fromIndex\uff0c\u4f46\u4e0d\u5305\u62ec\u00a0toIndex\uff09\uff1a\r\n\r\n\t\u4e3a\u6570\u7ec4\u5b50\u8303\u56f4\u4f7f\u7528\u00a0reverse()\u00a0\u53ef\u4ee5\u53cd\u8f6c\u5143\u7d20\u5728\u5b50\u8303\u56f4\u4e2d\u7684\u987a\u5e8f\u3002\r\n\t\u4e3a\u6570\u7ec4\u5b50\u8303\u56f4\u4f7f\u7528\u00a0sortDescending()\u00a0\u4f1a\u5728\u5b50\u8303\u56f4\u4e2d\u4ee5\u964d\u5e8f\u6392\u5217\u5143\u7d20\u3002\r\n\r\n[kotlin version=\"1.4-M2-preview\"]\r\nfun main() {\r\n\/\/sampleStart\r\nval letters = arrayOf(\"i\", \"o\", \"k\", \"l\", \"t\", \"n\")\r\nletters.reverse(0, 3)\r\nletters.sortDescending(2, 5)\r\nprintln(letters.contentToString()) \/\/ [k, o, t, l, i, n]\r\n\/\/sampleEnd\r\n}\r\n[\/kotlin]\r\n\u96c6\u5408 API \u4e2d\u7684\u65b0\u51fd\u6570\r\n\u5728 1.4-M2 \u4e2d\uff0c\u6211\u4eec\u7ee7\u7eed\u5728\u6807\u51c6\u5e93\u4e2d\u6269\u5c55\u96c6\u5408 API \u4ee5\u6db5\u76d6\u66f4\u591a\u5b9e\u9645\u7528\u4f8b\uff1a\r\n\r\n\r\n\t\u65b0\u7684\u96c6\u521b\u5efa\u51fd\u6570\u00a0setOfNotNull()\u00a0\u53ef\u4ee5\u8ba9\u96c6\u5305\u62ec\u6240\u63d0\u4f9b\u53c2\u6570\u4e2d\u7684\u6240\u6709\u975e\u7a7a\u9879\u3002\r\n\r\n\r\n[kotlin version=\"1.4-M2-preview\"]\r\nfun main() {\r\n\/\/sampleStart\r\nval set = setOfNotNull(null, 1, 2, 0, null)\r\nprintln(set)\r\n\/\/sampleEnd\r\n}\r\n[\/kotlin]\r\n\r\nshuffled()\u00a0\u73b0\u5728\u53ef\u7528\u4e8e\u5e8f\u5217\u3002\r\n\r\n[kotlin version=\"1.4-M2-preview\"]\r\nfun main() {\r\n\/\/sampleStart\r\nval numbers = (0 until 50).asSequence()\r\nval result = numbers.map { it * 2 }.shuffled().take(5)\r\nprintln(result.toList()) \/\/five random even numbers below 100\r\n\/\/sampleEnd\r\n}\r\n[\/kotlin]\r\n\r\n\r\n\r\n\tonEachIndexed()\u00a0\u548c\u00a0reduceIndexedOrNull()\u00a0\u5206\u522b\u4e3a\u00a0onEach()\u00a0\u548c\u00a0reduceOrNull()\u00a0\u7684\u5bf9\u5e94\u9879\u6dfb\u52a0\u3002\u60a8\u53ef\u80fd\u5df2\u7ecf\u77e5\u9053\uff0c\u96c6\u5408\u5904\u7406\u51fd\u6570\u540d\u79f0\u4e2d\u7684\u00a0Indexed\u00a0\u8868\u793a\u5e94\u7528\u7684\u64cd\u4f5c\u5c06\u5143\u7d20\u7d22\u5f15\u4f5c\u4e3a\u53c2\u6570\u3002\r\n\r\n\r\n\r\n[kotlin version=\"1.4-M2-preview\"]\r\nfun main() {\r\n\/\/sampleStart\r\nval list = mutableListOf(\"a\", \"b\", \"c\", \"d\").onEachIndexed {\r\nindex, item -> println(index.toString() + \":\" + item)\r\n}\r\n\r\nval emptyList = emptyList()\r\nemptyList.reduceIndexedOrNull {index, a, b -> index + a + b} \/\/ null\r\n\/\/sampleEnd\r\n}\r\n[\/kotlin]\r\n\r\n\r\n\trunningFold()\u00a0\u548c\u00a0runningReduce()\u00a0\u4f5c\u4e3a\u00a0scan()\u00a0\u548c\u00a0scanReduce()\u00a0\u7684\u540c\u4e49\u9879\u5f15\u5165\u3002\u6b64\u7c7b\u540d\u79f0\u4e0e\u76f8\u5173\u51fd\u6570\u00a0fold()\u00a0\u548c\u00a0reduce()\u00a0\u66f4\u4e00\u81f4\u3002\u672a\u6765\uff0cscan()\u00a0\u4e0e\u00a0runningFold()\u00a0\u90fd\u4f1a\u4f7f\u7528\uff0c\u56e0\u4e3a\u524d\u8005\u662f\u6b64\u64cd\u4f5c\u4f17\u6240\u5468\u77e5\u7684\u540d\u79f0\u3002\u4e0d\u8fc7\uff0c\u5b9e\u9a8c\u6027\u00a0scanReduce()\u00a0\u5c06\u88ab\u5f03\u7528\uff0c\u5e76\u4e14\u5f88\u5feb\u5c06\u88ab\u79fb\u9664\u3002\r\n\r\n\r\n[kotlin version=\"1.4-M2-preview\"]\r\nfun main() {\r\n\/\/sampleStart\r\nval numbers = mutableListOf(0, 1, 2, 3, 4, 5)\r\nval runningReduceSum = numbers.runningReduce() { sum, item -> sum + item} \/\/ [0, 1, 3, 6, 10, 15]\r\nval runningFoldSum = numbers.runningFold(10) { sum, item -> sum + item} \/\/ [10, 10, 11, 13, 16, 20, 25]\r\n\/\/sampleEnd\r\n}\r\n[\/kotlin]\r\n\u6539\u8fdb\u73b0\u6709 API\r\n\u7531\u4e8e Kotlin 1.4 \u662f\u4e00\u4e2a\u4e3b\u8981\u7684\u201c\u529f\u80fd\u201d\u7248\u672c\uff0c\u6211\u4eec\u53ef\u4ee5\u5411\u8be5\u8bed\u8a00\u4e2d\u6dfb\u52a0\u65b0\u529f\u80fd\uff0c\u4ee5\u53ca\u5411\u6807\u51c6\u5e93\u4e2d\u6dfb\u52a0\u65b0\u51fd\u6570\u6216\u63a5\u53e3\u3002\u6211\u4eec\u5728\u589e\u91cf\u7248\u672c\uff08\u4f8b\u5982 1.3.70\uff09\u4e2d\u4ec5\u6dfb\u52a0\u4e86\u65b0\u7684\u5b9e\u9a8c\u6027\u58f0\u660e\u3002\u5982\u679c\u60a8\u76ee\u524d\u4f7f\u7528 Kotlin 1.3.70 \u7f16\u5199\u4ee3\u7801\u5e76\u4e14\u6ca1\u6709\u4f7f\u7528\u4efb\u4f55\u5b9e\u9a8c\u6027\u58f0\u660e\uff0c\u4f7f\u7528 Kotlin 1.3.40 \u7684\u540c\u4e8b\u53ef\u4ee5\u6b63\u5e38\u7f16\u8bd1\u60a8\u7684\u4ee3\u7801\u3002\r\n\r\n\u672a\u6765\u7248\u672c\u4e0d\u9700\u8981\u4e0e\u6b21\u8981\u7248\u672c\u9075\u5faa\u76f8\u540c\u7684\u4e25\u683c\u89c4\u5219\uff0c\u4e5f\u5c31\u662f\u8bf4\uff0c\u5982\u679c\u60a8\u4f7f\u7528\u65b0\u529f\u80fd\u6216 API\uff0c1.3 \u7248\u7684 Kotlin \u7f16\u8bd1\u5668\u53ef\u80fd\u65e0\u6cd5\u7f16\u8bd1\u4f7f\u7528 Kotlin 1.4 \u7f16\u5199\u7684\u4ee3\u7801\u3002\u8fd9\u8ba9\u6211\u4eec\u53ef\u4ee5\u5728 API \u4e2d\u5f15\u5165\u4e00\u4e9b\u53d8\u66f4\u6765\u8fdb\u884c\u6539\u8fdb\u3002\u6211\u4eec\u786e\u5b9e\u5728\u4ed4\u7ec6\u89c2\u5bdf\u5411\u540e\u517c\u5bb9\u6027\uff0c\u4ee5\u4fbf\u8ba9\u60a8\u4e3a\u65e7\u7248\u672c\u7f16\u5199\u7684\u4ee3\u7801\u53ef\u4ee5\u5411\u4e4b\u524d\u4e00\u6837\u7f16\u8bd1\u548c\u8fd0\u884c\u3002\r\n\u5728 Kotlin 1.4 \u4e2d\uff0c\u6211\u4eec\u653e\u5bbd\u4e86\u591a\u4e2a\u51fd\u6570\uff0c\u4f7f\u5176\u53ef\u4ee5\u63a5\u53d7\u00a0null\uff1a\r\n\r\n[kotlin version=\"1.4-M2-preview\"]\r\nfun main() {\r\n\/\/sampleStart\r\nval s: String? = null\r\nprintln(s.toBoolean()) \/\/ false\r\n\/\/sampleEnd\r\n}\r\n[\/kotlin]\r\n\r\nKotlin 1.3 \u5c06\u4e0d\u4f1a\u7f16\u8bd1\u6b64\u4ee3\u7801\uff0c\u56e0\u4e3a\u5b83\u9700\u8981\u00a0String.toBoolean()\u00a0\u7684\u63a5\u6536\u5668\u4e0d\u53ef\u4e3a\u7a7a\u3002Kotlin 1.4 \u5c06\u8be5\u63a5\u6536\u5668\u66f4\u6539\u4e3a\u53ef\u7a7a\u5b57\u7b26\u4e32\uff1aString?.toBoolean()\u3002\u60a8\u4e4b\u524d\u7f16\u5199\u7684\u6240\u6709\u4ee3\u7801\u5728 Kotlin 1.4 \u4e2d\u4ecd\u53ef\u4ee5\u7f16\u8bd1\u548c\u8fd0\u884c\u3002\r\n\u76f8\u540c\u7684\u903b\u8f91\u540c\u6837\u9002\u7528\u4e8e\u00a0contentEquals\u3001contentHashCode\u00a0\u548c\u00a0contentToString\u00a0\u51fd\u6570\u7684\u00a0Array\u00a0\u63a5\u6536\u5668\uff1a\u5b83\u73b0\u5728\u53ef\u4ee5\u4e3a\u7a7a\u3002\r\n\u6b64\u5916\uff0cString.format()\u00a0\u73b0\u5728\u5141\u8bb8\u00a0null\u00a0\u4f5c\u4e3a\u00a0locale\u00a0\u53c2\u6570\uff0c\u5728\u8fd9\u79cd\u60c5\u51b5\u4e0b\uff0c\u4e0d\u4f1a\u5e94\u7528\u672c\u5730\u5316\u3002\r\n\r\n\u4ee5\u00a0Double\u00a0\u548c\u00a0Float\u00a0\u7c7b\u578b\u5b9a\u4e49\u7684\u4ee5\u4e0b\u5e38\u91cf\u73b0\u5728\u662f\u201c\u771f\u6b63\u7684\u201d\u5e38\u91cf\uff1a\r\n\r\n[kotlin version=\"1.4-M2-preview\"]\r\nfun main() {\r\n\/\/sampleStart\r\nprintln(Double.NaN) \/\/ NaN\r\nprintln(Double.NEGATIVE_INFINITY) \/\/ -Infinity\r\nprintln(Double.POSITIVE_INFINITY > Double.MAX_VALUE ) \/\/ true\r\nprintln(Double.SIZE_BITS) \/\/ 64\r\n\/\/sampleEnd\r\n}\r\n[\/kotlin]\r\n\r\n\u5b83\u4eec\u73b0\u5728\u5b9a\u4e49\u4e3a\u00a0const\u00a0\u53d8\u91cf\uff0c\u56e0\u6b64\uff0c\u60a8\u53ef\u4ee5\u5c06\u5176\u7528\u4f5c\u6ce8\u89e3\u53c2\u6570\u3002\r\nSIZE_BITS\u00a0\u548c\u00a0SIZE_BYTES\u00a0\u73b0\u5728\u662f\u00a0Double\u00a0\u548c\u00a0Float\u00a0\u7c7b\u578b\u7684\u65b0\u5e38\u91cf\uff1b\u5b83\u4eec\u5206\u522b\u5305\u542b\u7528\u4e8e\u4ee5\u4e8c\u8fdb\u5236\u5f62\u5f0f\u8868\u793a\u7c7b\u578b\u5b9e\u4f8b\u7684\u4f4d\u6570\u548c\u5b57\u8282\u6570\u3002\r\n\u8bf7\u6ce8\u610f\uff0c\u6211\u4eec\u8fd8\u5728 Kotlin\/JS \u4e2d\u66f4\u6539\u4e86\u00a0Float.MAX_VALUE\u00a0\u548c\u00a0Float.MIN_VALUE\u00a0\u503c\u3002\u4e4b\u524d\uff0c\u5b83\u4eec\u7b49\u4e8e JavaScript\u00a0Number.MAX\/MIN_VALUE\uff08\u76f8\u5f53\u4e8e\u00a0Double.MAX\/MIN_VALUE\uff09\uff0c\u56e0\u4e3a\u5728 Kotlin\/JS \u4e2d\uff0cFloat\u00a0\u672c\u8d28\u4e0a\u7b49\u4e8e\u00a0Double\u3002\u73b0\u5728\uff0c\u8fd9\u4e9b\u00a0Float\u00a0\u8303\u56f4\u5e38\u91cf\u5728\u6240\u6709\u5e73\u53f0\u4e2d\u90fd\u76f8\u540c\u3002\r\n\u5e26 vararg \u7684 maxOf() \u548c minOf()\r\n\u6807\u51c6\u5e93\u4e2d\u7684\u00a0maxOf()\u00a0\u548c\u00a0minOf()\u00a0\u51fd\u6570\u53ef\u4ee5\u67e5\u627e\u4e24\u4e2a\u503c\u4e2d\u7684\u8f83\u5927\u8005\u548c\u8f83\u5c0f\u8005\u3002\u4ece 1.4-M1 \u5f00\u59cb\uff0cmaxOf()\u00a0\u548c\u00a0minOf()\u00a0\u53ef\u4ee5\u63a5\u53d7\u53ef\u53d8\u6570\u91cf\u7684\u53c2\u6570\u00a0(vararg)\uff0c\u8fd9\u6837\u4e00\u6765\uff0c\u60a8\u53ef\u4ee5\u5c06\u5176\u7528\u4e8e\u4efb\u610f\u6570\u5b57\u7ec4\u6216\u5176\u4ed6\u53ef\u6bd4\u9879\u7ec4\u3002\r\n[kotlin version=\"1.4-M2-preview\"]\r\nfun main() {\r\n\/\/sampleStart\r\nval max = maxOf(1, 2, 3, 4)\r\nprintln(max)\r\n\/\/sampleEnd\r\n}\r\n[\/kotlin]\r\n\u5c5e\u6027\u59d4\u6258\u6539\u8fdb\r\n\u5728 Kotlin \u4e2d\uff0c\u59d4\u6258\u7684\u5c5e\u6027\u901a\u8fc7\u60ef\u4f8b\u800c\u4e0d\u662f\u63a5\u53e3\u8fd0\u884c\uff1a\u60a8\u60f3\u8981\u7528\u4f5c\u59d4\u6258\u7684\u7c7b\u578b\u5fc5\u987b\u5b9a\u4e49\u8fd0\u7b97\u7b26\u51fd\u6570\uff0c\u800c\u4e0d\u662f\u5b9e\u73b0\u6240\u9700\u63a5\u53e3\u3002\u8fd9\u63d0\u4f9b\u4e86\u7075\u6d3b\u6027\uff08\u56e0\u4e3a\u6211\u4eec\u4e0d\u53d7\u7279\u5b9a\u63a5\u53e3\u7684\u9650\u5236\uff09\uff0c\u4f46\u5728\u8bb8\u591a\u5b9e\u9645\u7528\u4f8b\u4e2d\uff0c\u4f7f\u7528\u63a5\u53e3\u4ecd\u7136\u6709\u7528\u3002\r\n\u5728 Kotlin 1.4 \u4e2d\uff0c\u6211\u4eec\u63d0\u5347\u4e86\u6b64\u7c7b\u8865\u5145\u6027\u63a5\u53e3\u7684\u9002\u7528\u6027\uff1a\u6211\u4eec\u5f15\u5165\u4e86\u65b0\u7684\u00a0PropertyDelegateProvider\u00a0\u63a5\u53e3\uff0cReadWriteProperty\u00a0\u73b0\u5728\u7ee7\u627f\u00a0ReadOnlyProperty\u3002\u8bf7\u7ee7\u7eed\u9605\u8bfb\u4ee5\u4e86\u89e3\u66f4\u591a\u8be6\u7ec6\u4fe1\u606f\u3002\r\n\r\n\u59d4\u6258\u8868\u8fbe\u5f0f\r\n\r\nReadWriteProperty\u00a0\u548c\u00a0ReadOnlyProperty\u00a0\u63a5\u53e3\u53ef\u7528\u4e8e\u5b9a\u4e49\u5c5e\u6027\u59d4\u6258\uff0c\u56e0\u4e3a\u60a8\u7684\u81ea\u5b9a\u4e49\u7c7b\u6216\u533f\u540d\u5bf9\u8c61\u53ef\u4ee5\u5b9e\u73b0\u5b83\u4eec\uff1a\r\n[kotlin runnable=false]\r\nfun myDelegate(): ReadWriteProperty<Nothing?, Int> =\r\nobject : ReadWriteProperty<Nothing?, Int> {\r\n...\r\n}\r\n\r\nval foo: Int by myDelegate()\r\nvar bar: Int by myDelegate()\r\n[\/kotlin]\r\n\u4ece 1.4 \u5f00\u59cb\uff0cReadWriteProperty\u00a0\u7ee7\u627f\u00a0ReadOnlyProperty\u3002\u8fd9\u8ba9\u60a8\u53ef\u4ee5\u66f4\u7075\u6d3b\u5730\u4f7f\u7528\u59d4\u6258\u8868\u8fbe\u5f0f\u3002\u5728\u6211\u4eec\u7684\u793a\u4f8b\u4e2d\uff0c\u73b0\u5728\u6bcf\u5f53\u5e94\u8be5\u51fa\u73b0\u00a0ReadOnlyProperty\u00a0\u65f6\uff0c\u60a8\u5c31\u53ef\u4ee5\u4f20\u9012\u00a0myDelegate()\u00a0\u8c03\u7528\u3002\r\n\u5728\u8fd9\u91cc\u6211\u4eec\u60f3\u5f3a\u8c03\u4e00\u4e0b\uff0c\u201c\u53ea\u8bfb\u201d\u4e0e Kotlin \u4e2d\u7684\u201c\u4e0d\u53ef\u53d8\u201d\u4e0d\u540c\uff0c\u7c7b\u4f3c\u4e8e\u53ea\u8bfb\u5217\u8868\u5e76\u4e0d\u662f\u4e0d\u53ef\u53d8\u5217\u8868\u3002\u201c\u53ea\u8bfb\u201d\u7684\u610f\u601d\u662f\u201c\u6b64\u63a5\u53e3\u4ec5\u63d0\u4f9b\u5bf9\u76f8\u5173\u5bf9\u8c61\u7684\u53ea\u8bfb\u8bbf\u95ee\u6743\u9650\u201d\u3002\r\n\u63d0\u4f9b\u59d4\u6258\r\n\u4f7f\u7528\u63d0\u4f9b\u59d4\u6258\u7684\u673a\u5236\uff0c\u60a8\u53ef\u4ee5\u6269\u5c55\u521b\u5efa\u201c\u59d4\u6258\u201d\u5bf9\u8c61\uff08\u5c5e\u6027\u5b9e\u73b0\u6240\u59d4\u6258\u5230\u7684\u5bf9\u8c61\uff09\u7684\u903b\u8f91\u3002\r\n\u60a8\u53ef\u4ee5\u5728\u6587\u6863\u4e2d\u627e\u5230\u5176\u5de5\u4f5c\u539f\u7406\u7684\u8be6\u7ec6\u4fe1\u606f\u3002\u5728 1.4 \u4e2d\uff0c\u4e3a\u4e86\u8ba9\u6b64\u673a\u5236\u66f4\u52a0\u65b9\u4fbf\uff0c\u6211\u4eec\u6dfb\u52a0\u4e86\u65b0\u7684\u00a0PropertyDelegateProvider\u00a0\u63a5\u53e3\u3002\u5982\u679c\u60a8\u4e0d\u60f3\u989d\u5916\u521b\u5efa\u7c7b\u5e76\u503e\u5411\u4e8e\u4f7f\u7528\u533f\u540d\u5bf9\u8c61\uff0c\u53ef\u4ee5\u4f7f\u7528\u8be5\u63a5\u53e3\uff0c\u7c7b\u4f3c\u4e8e\u6211\u4eec\u5728\u4e0a\u9762\u7684\u00a0myDelegate()\u00a0\u793a\u4f8b\u4e2d\u770b\u5230\u7684\u4e00\u6837\u3002\r\n\u59d4\u6258\u7ed9\u53e6\u4e00\u4e2a\u5c5e\u6027\r\n\u4ece 1.4 \u5f00\u59cb\uff0c\u4e00\u4e2a\u5c5e\u6027\u53ef\u4ee5\u76f4\u63a5\u5c06\u5176 getter \u548c setter \u59d4\u6258\u7ed9\u53e6\u4e00\u4e2a\u5c5e\u6027\u3002\u5982\u679c\u60a8\u60f3\u4ee5\u5411\u540e\u517c\u5bb9\u7684\u65b9\u5f0f\u79fb\u9664\u67d0\u4e2a\u5c5e\u6027\uff0c\u8fd9\u6837\u53ef\u80fd\u5f88\u6709\u7528\uff1a\u5f15\u5165\u4e00\u4e2a\u65b0\u5c5e\u6027\uff0c\u4f7f\u7528\u00a0@Deprecated\u00a0\u6ce8\u89e3\u65e7\u5c5e\u6027\uff0c\u7136\u540e\u59d4\u6258\u5176\u5b9e\u73b0\u3002\r\n\r\n[kotlin version=\"1.4-M2-preview\"]\r\nclass MyClass {\r\nvar newName: Int = 0\r\n@Deprecated(\"Use 'newName' instead\", ReplaceWith(\"newName\"))\r\nvar oldName: Int by this::newName\r\n}\r\n\r\nfun main() {\r\nval myClass = MyClass()\r\n\/\/ Notification: 'oldName: Int' is deprecated.\r\n\/\/ Use 'newName' instead\r\nmyClass.oldName = 42\r\nprintln(myClass.newName) \/\/ 42\r\n}\r\n[\/kotlin]\r\n\r\n\u4e4b\u524d\u4ecb\u7ecd\u7684\u5bf9\u5df2\u7f16\u8bd1\u59d4\u6258\u5c5e\u6027\u7684\u4f18\u5316\u9002\u7528\u4e8e\u8fd9\u79cd\u60c5\u51b5\u3002\u7531\u4e8e\u59d4\u6258\u8fd0\u7b97\u7b26\u5b9e\u73b0\u4e0d\u4f7f\u7528\u6b63\u5728\u59d4\u6258\u7684\u5c5e\u6027\u7684\u76f8\u5173\u4fe1\u606f (oldName)\uff0c\u7f16\u8bd1\u5668\u4e0d\u9700\u8981\u751f\u6210\u5305\u542b\u8be5\u4fe1\u606f\u7684\u00a0KProperty\u00a0\u5b9e\u4f8b\u3002\u672a\u6765\uff0c\u60a8\u8fd8\u53ef\u4ee5\u4e0d\u7528\u4e3a\u59d4\u6258\u751f\u6210\u989d\u5916\u7684\u00a0KMutableProperty\u00a0\u5b9e\u4f8b (newName) \u3002\r\n\u5982\u4f55\u8bd5\u7528\r\n\u672c\u6587\u4ecb\u7ecd\u7684\u6240\u6709\u53d8\u5316\u90fd\u4f1a\u4f53\u73b0\u5728 Kotlin 1.4-M2 \u7248\u672c\u4e2d\uff0c\u4e0d\u8fc7\uff0c\u60a8\u73b0\u5728\u5c31\u53ef\u4ee5\u5728\u00a0play.kotl.in\u00a0\u4e0a\u5728\u7ebf\u8bd5\u7528\u3002\r\n\u9884\u53d1\u5e03\u8bf4\u660e\r\n\u8bf7\u6ce8\u610f\uff0c\u540e\u5411\u517c\u5bb9\u6027\u4fdd\u8bc1\u4e0d\u6db5\u76d6\u9884\u53d1\u5e03\u7248\u672c\u3002\u529f\u80fd\u548c API \u5728\u540e\u7eed\u7248\u672c\u4e2d\u53ef\u80fd\u6839\u636e\u7528\u6237\u53cd\u9988\u8fdb\u884c\u66f4\u6539\u3002\r\n\u5206\u4eab\u60a8\u7684\u53cd\u9988\r\n\u611f\u8c22\u5927\u5bb6\u5728\u6211\u4eec\u7684\u95ee\u9898\u8ddf\u8e2a\u5668\u4e2d\u63d0\u4ea4\u9519\u8bef\u62a5\u544a\u3002\r\n\r\n\u6211\u4eec\u5c06\u5c3d\u529b\u5728\u6700\u7ec8\u7248\u672c\u4e4b\u524d\u4fee\u590d\u6240\u6709\u91cd\u8981\u95ee\u9898\uff0c\u56e0\u6b64\uff0c\u60a8\u4e0d\u7528\u7b49\u5230\u4e0b\u4e00\u4e2a Kotlin \u7248\u672c\u5373\u53ef\u770b\u5230\u95ee\u9898\u5f97\u5230\u89e3\u51b3\u3002\r\n\r\n\u5982\u679c\u60a8\u60f3\u63d0\u95ee\uff0c\u53c2\u4e0e\u8ba8\u8bba\u4ee5\u53ca\u83b7\u53d6\u65b0\u7684\u9884\u89c8\u7248\u672c\u7684\u901a\u77e5\uff0c\u6b22\u8fce\u52a0\u5165\u6211\u4eec\u5728\u00a0Kotlin Slack\u00a0\u4e2d\u7684\u00a0\\#eap\u00a0\u9891\u9053\uff08\u5728\u6b64\u5904\u83b7\u53d6\u9080\u8bf7\uff09\u3002\r\n\r\nLet's Kotlin!","protected":false},"excerpt":{"rendered":"\u6211\u4eec\u5df2\u51c6\u5907\u597d\u5728\u6b64\u9884\u89c8\u7248\u4e2d\u5f15\u5165\u4e00\u4e9b\u6539\u8fdb\uff1b\u5728\u8fd9\u7bc7\u535a\u6587\u4e2d\uff0c\u6211\u4eec\u5c06\u4ecb\u7ecd\u6807\u51c6\u5e93\u7684\u53d8\u5316\u3002\u4ee5\u4e0b\u662f 1.4-M2 \u4e2d\u6807\u51c6\u5e93\u7684\u4e00\u4e9b\u4e3b\u8981\u6539\u8fdb\uff1a\t\u73b0\u6709 API 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