{"id":1089,"date":"2019-12-08T22:06:00","date_gmt":"2019-12-08T14:06:00","guid":{"rendered":"https:\/\/www.ray650128.com\/wordpress\/?p=1089"},"modified":"2021-08-15T22:23:31","modified_gmt":"2021-08-15T14:23:31","slug":"%e8%bd%89%e8%bc%89%e4%b8%8d%e8%a6%81%e7%94%a8java%e7%9a%84%e8%aa%9e%e6%b3%95%e6%80%9d%e7%b6%ad%e4%be%86%e5%af%abkotlin","status":"publish","type":"post","link":"https:\/\/blog.ray650128.com\/?p=1089","title":{"rendered":"[\u8f49\u8f09]\u4e0d\u8981\u7528Java\u7684\u8a9e\u6cd5\u601d\u7dad\u4f86\u5bebKotlin"},"content":{"rendered":"\n<p>\u4f5c\u8005\uff1a<a href=\"https:\/\/user.open-open.com\/u\/239573\">lnbnuaa<\/a><\/p>\n\n\n\n<p>\u4f86\u6e90\uff1a<a rel=\"noreferrer noopener\" href=\"https:\/\/www.techug.com\/post\/java-vs-kotlin.html\" target=\"_blank\">https:\/\/www.open-open.com\/lib\/view\/open1520780386284.html#articleHeader1<\/a><\/p>\n\n\n\n<p>\u4ee5\u4e0b\u6587\u7ae0\u958b\u59cb<\/p>\n\n\n\n<hr class=\"wp-block-separator\"\/>\n\n\n\n<figure class=\"wp-block-image\"><img decoding=\"async\" src=\"https:\/\/cdn.jiler.cn\/techug\/uploads\/2018\/03\/blog-2-main-1024x538-1000x525.jpg\" alt=\"\" class=\"wp-image-35403\"\/><\/figure>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p>\u5199\u4e86\u591a\u5e74\u7684Java\uff0c\u76f4\u5230\u770b\u5230Kotlin\uff0c\u539f\u6765\u4ee3\u7801\u53ef\u4ee5\u5982\u6b64\u4f18\u96c5\uff01<\/p><\/blockquote>\n\n\n\n<p>\u5982\u679c\u4f60\u662f\u50cf\u6211\u4e00\u6837\u662f\u4e00\u540d<code>\u4f18\u79c0<\/code>\u7684Java\u5f00\u53d1\u8005<code>^_^<\/code>\uff0c\u800c\u4e14\u5df2\u7ecf\u60f3\u7528kotlin\u6765\u5b9e\u73b0\u4f60\u7684\u7a0b\u5e8f\uff0c\u90a3\u4e48\uff0c\u62b1\u6b49\uff01\u4e0d\u8981\u7528Java\u7684\u8bed\u6cd5\u601d\u7ef4\u6765\u5199Kotlin\uff0c\u4e0d\u8981\u8ba9kotlin\u7684\u4f18\u96c5\u57cb\u6ca1\u3002\u5982\u679c\u4f60\u6ca1\u6709Java\u5f00\u53d1\u7ecf\u9a8c\uff0c\u4e0b\u9762\u7684\u5185\u5bb9\u4e5f\u5bf9\u4f60\u4f1a\u6709\u5e2e\u52a9\u3002\u3002\u3002<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">1.\u5c3d\u53ef\u80fd\u7684\u5c11\u7528 <code>!!<\/code><\/h1>\n\n\n\n<p>\u4e2a\u4eba\u611f\u89c9\u5bf9\u4e8eNull\u7684\u68c0\u67e5\u662fKoltin\u6700\u8bed\u6cd5\u7cd6\u7684\u4e1c\u897f\u4e86\uff0c\u5f3a\u5236\u5728\u7f16\u7801\u8fc7\u7a0b\u4e2d\u8003\u8651\u7a7a\u6307\u9488\uff0c\u56e0\u6b64<a href=\"http:\/\/en.wikipedia.org\/wiki\/Tony_Hoare#Apologies_and_retractions\" target=\"_blank\" rel=\"noreferrer noopener\">\u300a\u5341\u4ebf\u7f8e\u5143\u7684\u9519\u8bef\u300b<\/a>\uff0c\u4e5f\u8bb8\u4f60\u4e0d\u4f1a\u518d\u6709\u8fd9\u4e2a\u673a\u4f1a\u72af\u9519\u4e86\uff08\u4e5f\u8bb8\u53ef\u4ee5\u8bf4\u6210\uff0c\u4f60\u8d5a\u4e86\u5341\u4ebf\u7f8e\u91d1<code>^_^<\/code>\uff09\u3002<\/p>\n\n\n\n<p>\u9996\u5148\u9700\u8981\u4ecb\u7ecd\u662f<code>!!<\/code>\u64cd\u4f5c\u7b26\u3002<\/p>\n\n\n\n<p><code>!!<\/code> \u64cd\u4f5c\u7b26\uff1a<code>\u8fd9\u662f\u4e3a\u7a7a\u6307\u9488\u7231\u597d\u8005\u51c6\u5907\u7684<\/code>\uff0c\u975e\u7a7a\u65ad\u8a00\u8fd0\u7b97\u7b26\uff08!!\uff09\u5c06\u4efb\u4f55\u503c\u8f6c\u6362\u4e3a\u975e\u7a7a\u7c7b\u578b\uff0c\u82e5\u8be5\u503c\u4e3a\u7a7a\u5219\u629b\u51fa\u5f02\u5e38\u3002\u6211\u4eec\u53ef\u4ee5\u5199 a!! \uff0c\u8fd9\u4f1a\u8fd4\u56de\u4e00\u4e2a\u975e\u7a7a\u7684 a \u503c \uff08\u4f8b\u5982\uff1a\u5728\u6211\u4eec\u4f8b\u5b50\u4e2d\u7684 String\uff09\u6216\u8005\u5982\u679c a \u4e3a\u7a7a\uff0c\u5c31\u4f1a\u629b\u51fa\u4e00\u4e2a \u7a7a\u6307\u9488 \u5f02\u5e38\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">val b = a!!.length<\/code><\/pre>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p>\u6240\u4ee5\uff0c\u6211\u4eec\u80fd\u4e0d\u7528<code>!!<\/code>\u64cd\u4f5c\u7b26\u5c31\u4e0d\u8981\u7528\u3002\u3002\u3002<\/p><\/blockquote>\n\n\n\n<p>\u4e0b\u9762\u4ecb\u7ecd\u51e0\u79cd\u65b9\u5f0f\u907f\u514d\u4f7f\u7528<code>!!<\/code>\u64cd\u4f5c\u7b26<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">1).\u591a\u7528 val \u800c\u4e0d\u662f var<\/h2>\n\n\n\n<p>\u5728 Kotlin \u4e2d <code>val<\/code>\u4ee3\u8868\u53ea\u8bfb\uff0c<code>var<\/code>\u4ee3\u8868\u53ef\u53d8\u3002\u5efa\u8bae\u5c3d\u53ef\u80fd\u591a\u7684\u4f7f\u7528<code>val<\/code>\u3002<code>val<\/code>\u662f\u7ebf\u7a0b\u5b89\u5168\u7684\uff0c\u5e76\u4e14\u5fc5\u987b\u5728\u5b9a\u4e49\u65f6\u521d\u59cb\u5316\uff0c\u6240\u4ee5\u4e0d\u9700\u8981\u62c5\u5fc3 null \u7684\u95ee\u9898\u3002\u53ea\u9700\u8981\u6ce8\u610f val \u5728\u67d0\u4e9b\u60c5\u51b5\u4e0b\u4e5f\u662f\u53ef\u53d8\u7684\u5c31\u884c\u4e86\u3002<\/p>\n\n\n\n<p>val \u548c var \u662f\u7528\u4e8e\u8868\u793a\u5c5e\u6027\u662f\u5426\u6709 getter\/setter\uff1a<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>var\uff1a\u540c\u65f6\u6709 getter \u548c setter<\/li><li>val\uff1a\u53ea\u6709 getter<\/li><\/ul>\n\n\n\n<p>\u6240\u4ee5\uff0c\u5f3a\u70c8\u63a8\u8350\u80fd\u7528<code>val<\/code>\u7684\u5730\u65b9\u5c31\u7528<code>val<\/code>\u3002<\/p>\n\n\n\n<h2 class=\"wp-block-heading\">2).\u4f7f\u7528 lateinit<\/h2>\n\n\n\n<p>\u6709\u4e9b\u65f6\u5019\u5e76\u4e0d\u80fd\u7528val\uff0c\u6bd4\u5982\u5728<code>spring boot<\/code>\u63a5\u53e3\u6d4b\u8bd5\u4e2d\u5c31\u4e0d\u80fd\u4f7f\u7528<code>val<\/code>,\u5bf9\u4e8e\u8fd9\u79cd\u60c5\u51b5\uff0c\u53ef\u4ee5\u4f7f\u7528 lateinit \u5173\u952e\u5b57\u3002\u3002<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p>\u4f9d\u8d56\u5012\u8f6c\uff0c\u5bf9\u8c61\u7684\u521b\u5efa\u662f\u901a\u8fc7spring\u5b8c\u6210\u7684\uff0c\u800cval\u8981\u6c42\u5b9a\u4e49\u7684\u65f6\u5019\u521d\u59cb\u5316<\/p><\/blockquote>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">\/**\n * Created by quanke on 2018\/1\/9.\n * Site:http:\/\/woquanke.com .\n *\/\n@RunWith(SpringRunner::class)\n@SpringBootTest(webEnvironment = SpringBootTest.WebEnvironment.RANDOM_PORT)\nclass ApplicationTests {\n    val log = LogFactory.getLog(ApplicationTests::class.java)!!\n    @Autowired\n    lateinit var restTemplate: TestRestTemplate\n    \n    @Test\n    fun `GET when given quanke then returns \"Hello, quanke\"`() {\n        \/\/ Given\n        val name = \"quanke\"\n        \/\/ When\n        val body = restTemplate.getForObject(\"\/users\/hello\/{name}\", String::class.java, name)\n        \/\/ Then\n        assertThat(body).isEqualTo(\"Hello, $name\")\n    }\n}<\/code><\/pre>\n\n\n\n<p>\u6ce8\u610f:lateinit\u5f88\u597d\u7528\uff0c\u4f46\u4e5f\u6709\u5751<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>\u8bbf\u95ee\u672a\u521d\u59cb\u5316\u7684 lateinit \u5c5e\u6027\u4f1a\u5bfc\u81f4 UninitializedPropertyAccessException\u3002<\/li><li>lateinit \u4e0d\u652f\u6301\u57fa\u7840\u6570\u636e\u7c7b\u578b\uff0c\u6bd4\u5982 Int\u3002\u5bf9\u4e8e\u57fa\u7840\u6570\u636e\u7c7b\u578b\uff0c\u6211\u4eec\u53ef\u4ee5\u8fd9\u6837\uff1a &gt; private var mNumber: Int by Delegates.notNull&lt;Int&gt;() &gt;<\/li><\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">3).Elvis \u64cd\u4f5c\u7b26<\/h2>\n\n\n\n<p>\u5f53b\u4e3a\u53ef\u7a7a\u5f15\u7528\u65f6\uff0c\u6211\u4eec\u53ef\u4ee5\u4f7f\u7528if\u8868\u8fbe\u5f0f\u5904\u7406<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">val l: Int = if (b != null) b.length else -1<\/code><\/pre>\n\n\n\n<p>\u4f46\u66f4\u52a0\u4f18\u96c5\u7684\u65b9\u5f0f\u662f\u4f7f\u7528Elvis \u64cd\u4f5c\u7b26<code>?:<\/code><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">val l = b?.length ?: -1<\/code><\/pre>\n\n\n\n<p>\u5982\u679c ?: \u5de6\u4fa7\u8868\u8fbe\u5f0f\u975e\u7a7a\uff0celvis \u64cd\u4f5c\u7b26\u5c31\u8fd4\u56de\u5176\u5de6\u4fa7\u8868\u8fbe\u5f0f\uff0c\u5426\u5219\u8fd4\u56de\u53f3\u4fa7\u8868\u8fbe\u5f0f\u3002<\/p>\n\n\n\n<blockquote class=\"wp-block-quote is-layout-flow wp-block-quote-is-layout-flow\"><p>\u6ce8\u610f:\u5f53\u4e14\u4ec5\u5f53\u5de6\u4fa7\u4e3a\u7a7a\u65f6\uff0c\u624d\u4f1a\u5bf9\u53f3\u4fa7\u8868\u8fbe\u5f0f\u6c42\u503c\u3002<\/p><\/blockquote>\n\n\n\n<h2 class=\"wp-block-heading\">4).\u4e5f\u8bb8\u53ef\u4ee5\u5c1d\u8bd5\u4e00\u4e0blet\u51fd\u6570<\/h2>\n\n\n\n<p><code>let<\/code>\u51fd\u6570\u4e00\u822c\u4e0e\u5b89\u5168\u8c03\u7528\u64cd\u4f5c\u7b26\u4e00\u8d77\u4f7f\u7528,\u6211\u4eec\u9996\u5148\u4ecb\u7ecd\u5b89\u5168\u8c03\u7528\u64cd\u4f5c<code>?.<\/code><\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">b?.length<\/code><\/pre>\n\n\n\n<p>\u5982\u679c b \u975e\u7a7a\uff0c\u5c31\u8fd4\u56de b.length\uff0c\u5426\u5219\u8fd4\u56de null\uff0c\u8fd9\u4e2a\u8868\u8fbe\u5f0f\u7684\u7c7b\u578b\u662f Int?\u3002<\/p>\n\n\n\n<p>\u5b89\u5168\u8c03\u7528\u5728\u94fe\u5f0f\u8c03\u7528\u4e2d\u5f88\u6709\u7528\u3002\u4f8b\u5982\uff0c\u5982\u679c\u4e00\u4e2a\u5458\u5de5Quanke\u53ef\u80fd\u4f1a\uff08\u6216\u8005\u4e0d\u4f1a\uff09\u5206\u914d\u7ed9\u4e00\u4e2a\u90e8\u95e8\uff0c \u5e76\u4e14\u53ef\u80fd\u6709\u53e6\u5916\u4e00\u4e2a\u5458\u5de5\u662f\u8be5\u90e8\u95e8\u7684\u8d1f\u8d23\u4eba\uff0c\u90a3\u4e48\u83b7\u53d6 Quanke \u6240\u5728\u90e8\u95e8\u8d1f\u8d23\u4eba\uff08\u5982\u679c\u6709\u7684\u8bdd\uff09\u7684\u540d\u5b57\uff0c\u6211\u4eec\u5199\u4f5c\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">quanke?.department?.head?.name<\/code><\/pre>\n\n\n\n<p>\u5982\u679c\u4efb\u610f\u4e00\u4e2a\u5c5e\u6027\uff08\u73af\u8282\uff09\u4e3a\u7a7a\uff0c\u8fd9\u4e2a\u94fe\u5f0f\u8c03\u7528\u5c31\u4f1a\u8fd4\u56de null\u3002<\/p>\n\n\n\n<p>\u5982\u679c\u8981\u53ea\u5bf9\u975e\u7a7a\u503c\u6267\u884c\u67d0\u4e2a\u64cd\u4f5c\uff0c\u5b89\u5168\u8c03\u7528\u64cd\u4f5c\u7b26\u53ef\u4ee5\u4e0e let \u4e00\u8d77\u4f7f\u7528\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">val listWithNulls: List&lt;String?&gt; = listOf(\"A\", null)\nfor (item in listWithNulls) {\n     item?.let { println(it) } \/\/ \u8f93\u51fa A \u5e76\u5ffd\u7565 null\n}<\/code><\/pre>\n\n\n\n<p>\u8fd8\u6709\u4e00\u79cd\u5e38\u89c1\u7684\u9519\u8bef\uff08\u653eide\u91cc\u9762\u8bd5\u8bd5\u5c31\u77e5\u9053\u4ec0\u4e48\u9519\u8bef\u4e86\uff09\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">private var a: String? = null\nfun aLetDemo() {\n    if (a != null) {\n        test(a)\n    }\n}<\/code><\/pre>\n\n\n\n<p>\u6211\u4eec\u53ef\u4ee5\u8fd9\u6837\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">private var a: String? = null\nfun aLetDemo() {\n    if (a != null) {\n        test(a!!)\n    }\n}<\/code><\/pre>\n\n\n\n<p>\u4f46\u662f\u8fd9\u6837\u7684\u540e\u679c\u5c31\u662f\u4f60\u8fd8\u662f\u9700\u8981\u5728test\u51fd\u6570\u91cc\u5904\u7406\u7a7a\u6307\u9488\u3002<\/p>\n\n\n\n<p>\u6211\u4eec\u5145\u5206\u5229\u7528<code>?.<\/code>\u52a0<code>let<\/code>\u7684\u7279\u70b9\uff0c\u66f4\u52a0\u4f18\u96c5\u7684\u89e3\u51b3\u8fd9\u4e2a\u7f16\u8bd1\u9519\u8bef\uff0c\u5982\u4e0b<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">private var a: String? = null\nfun aLetDemo() {\n    if (a != null) {\n        a?.let {\n            test(it)\n        }\n    }\n}<\/code><\/pre>\n\n\n\n<h1 class=\"wp-block-heading\">2.\u5c11\u5199\u70b9Util\u7c7b\u548c\u7ee7\u627f<\/h1>\n\n\n\n<p>\u5f88\u591a\u65f6\u5019\u6846\u67b6\u63d0\u4f9b\u7ed9\u6211\u7684\u65b9\u6cd5\u662f\u6bd4\u8f83\u539f\u5b50\uff0c\u6216\u8005\u67d0\u4e9b\u5e38\u7528\u7684\u65b9\u6cd5\u6846\u67b6\u5e76\u6ca1\u6709\u63d0\u4f9b\uff0cJava\u4e00\u822c\u662f\u5199\u4e00\u4e2a\u5de5\u5177\u7c7b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">public final class StringUtil {\n    \/**\n     * \u5220\u9664\u6240\u6709\u7684\u6807\u70b9\u7b26\u53f7\n     *\n     * @param str \u5904\u7406\u7684\u5b57\u7b26\u4e32\n     *\/\n    public  static String trimPunct(String str) {\n        if(isEmpty(str)){\n            return \"\";\n        }\n        return str.replaceAll(\"[\\\\pP\\\\p{Punct}]\", \"\");\n    }\n}<\/code><\/pre>\n\n\n\n<p>Kotlin\u53ef\u4ee5\u901a\u8fc7\u6269\u5c55\u51fd\u6570\u7684\u5f62\u5f0f\u5b9e\u73b0\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">\/**\n * \u5220\u9664\u6240\u6709\u7684\u6807\u70b9\u7b26\u53f7\n *\n * @param str \u5904\u7406\u7684\u5b57\u7b26\u4e32\n *\/\nfun String.trimPunct(): String {\n    return if (this.isEmpty()) {\n        \"\"\n    } else this.replace(\"[\\\\pP\\\\p{Punct}]\".toRegex(), \"\")\n}<\/code><\/pre>\n\n\n\n<p>\u8c03\u7528\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">fun main(args: Array&lt;String&gt;) {\n    val a = \"\u628a\u6211\u7684\u6807\u70b9\u7b26\u53f7\u53bb\u6389\u5427\uff0c\u5168\u79d1\u3002\"\n    print(a.trimPunct())\n}<\/code><\/pre>\n\n\n\n<p>\u6253\u5370\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code class=\"\">\u628a\u6211\u7684\u6807\u70b9\u7b26\u53f7\u53bb\u6389\u5427\u5168\u79d1\nProcess finished with exit code 0<\/code><\/pre>\n\n\n\n<h1 class=\"wp-block-heading\">3.\u522b\u518d\u7528+\u53f7\u62fc\u63a5\u5b57\u7b26\u4e32<\/h1>\n\n\n\n<p>\u65e0\u8bba\u662fJava\u8fd8\u662fAndroid\u5f00\u53d1\uff0c\u6211\u4eec\u90fd\u4f1a\u7528\u5230\u5b57\u7b26\u4e32\u62fc\u63a5\uff0c\u6bd4\u5982\u8fdb\u884c\u65e5\u5fd7\u8f93\u51fa\u7b49\u7b49\u3002\u5728Kotlin\u4e2d\uff0c\u652f\u6301\u5b57\u7b26\u4e32\u6a21\u677f\uff0c\u6211\u4eec\u53ef\u4ee5\u5f88\u8f7b\u677e\u7684\u5b8c\u6210\u4e00\u4e2a\u5b57\u7b26\u4e32\u6570\u7684\u62fc\u63a5\uff0c\u5f53\u7136\u4f60\u53ef\u80fd\u4f1a\u8bf4\u4f7f\u7528StringBuilder\u6027\u80fd\u66f4\u597d\uff0c\u6bd4\u5982\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">val site = \"http:\/\/woquanke.com\"\nval sb: StringBuilder = StringBuilder()\nsb.append(\"\u6211\u7684\u535a\u5ba2\u540d\u5b57\u53eb\u300a\u6211\u5168\u79d1\u300b\uff0c\u6211\u7684\u535a\u5ba2\u5730\u5740\u662f\uff1a\")\nsb.append(site)\nprintln(sb.toString())<\/code><\/pre>\n\n\n\n<p>\u4f46kotlin\u7684\u5b57\u7b26\u4e32\u6a21\u7248\u53ef\u4ee5\u4f18\u96c5\u7684\u505a\u8fd9\u4e2a\u4e8b\u60c5\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">val site = \"http:\/\/woquanke.com\"\nprintln(\"\u6211\u7684\u535a\u5ba2\u540d\u5b57\u53eb\u300a\u6211\u5168\u79d1\u300b\uff0c\u6211\u7684\u535a\u5ba2\u5730\u5740\u662f\uff1a$site\")<\/code><\/pre>\n\n\n\n<h1 class=\"wp-block-heading\">4.\u4e5f\u8bb8\u53ef\u4ee5\u5fd8\u8bb0getters\/setters\u4e86<\/h1>\n\n\n\n<p>\u6211\u4eec\u7ecf\u5e38\u521b\u5efa\u4e00\u4e9b\u53ea\u4fdd\u5b58\u6570\u636e\u7684\u7c7b\u3002\u5728\u8fd9\u4e9b\u7c7b\u4e2d\uff0c\u4e00\u4e9b\u6807\u51c6\u51fd\u6570\u5f80\u5f80\u662f\u64cd\u4f5c\u4e00\u4e0bide\u751f\u6210\u7684\u3002\u5728 Kotlin \u4e2d\uff0c\u8fd9\u53eb\u505a \u6570\u636e\u7c7b \u5e76\u6807\u8bb0\u4e3a data\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">data class User(val name: String, val age: Int)<\/code><\/pre>\n\n\n\n<p>data class \u81ea\u52a8\u751f\u6210getter\uff0csetting\uff0chashcode\u548cequals\u7b49\u65b9\u6cd5<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">5.\u8bf7\u5fd8\u8bb0\u4e09\u5143\u8fd0\u7b97\u7b26<\/h1>\n\n\n\n<p>\u5728 Kotlin \u4e2d\uff0cif\u662f\u4e00\u4e2a\u8868\u8fbe\u5f0f\uff0c\u5373\u5b83\u4f1a\u8fd4\u56de\u4e00\u4e2a\u503c\u3002\u56e0\u6b64\u5c31\u4e0d\u9700\u8981\u4e09\u5143\u8fd0\u7b97\u7b26\uff08\u6761\u4ef6 ? \u7136\u540e : \u5426\u5219\uff09\uff0c\u56e0\u4e3a\u666e\u901a\u7684 if \u5c31\u80fd\u80dc\u4efb\u8fd9\u4e2a\u89d2\u8272\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">\/\/ \u4f5c\u4e3a\u8868\u8fbe\u5f0f\nval max = if (a &gt; b) a else b<\/code><\/pre>\n\n\n\n<h1 class=\"wp-block-heading\">6.\u54ea\u91cc\u8fd8\u6709switch<\/h1>\n\n\n\n<p>when \u53d6\u4ee3\u4e86\u7c7bjava \u8bed\u8a00\u7684 switch \u64cd\u4f5c\u7b26\u3002\u5176\u6700\u7b80\u5355\u7684\u5f62\u5f0f\u5982\u4e0b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">when (x) {\n    1 -&gt; print(\"x == 1\")\n    2 -&gt; print(\"x == 2\")\n    else -&gt; { \/\/ \u6ce8\u610f\u8fd9\u4e2a\u5757\n        print(\"x is neither 1 nor 2\")\n    }\n}<\/code><\/pre>\n\n\n\n<p>\u5982\u679c\u5f88\u591a\u5206\u652f\u9700\u8981\u7528\u76f8\u540c\u7684\u65b9\u5f0f\u5904\u7406\uff0c\u5219\u53ef\u4ee5\u628a\u591a\u4e2a\u5206\u652f\u6761\u4ef6\u653e\u5728\u4e00\u8d77\uff0c\u7528\u9017\u53f7\u5206\u9694\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">when (x) {\n    0, 1 -&gt; print(\"x == 0 or x == 1\")\n    else -&gt; print(\"otherwise\")\n}<\/code><\/pre>\n\n\n\n<p>\u53ef\u4ee5\u7528\u4efb\u610f\u8868\u8fbe\u5f0f\uff08\u800c\u4e0d\u53ea\u662f\u5e38\u91cf\uff09\u4f5c\u4e3a\u5206\u652f\u6761\u4ef6<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">when (x) {\n    parseInt(s) -&gt; print(\"s encodes x\")\n    else -&gt; print(\"s does not encode x\")\n}<\/code><\/pre>\n\n\n\n<p>\u4e5f\u53ef\u4ee5\u68c0\u6d4b\u4e00\u4e2a\u503c\u5728\uff08in\uff09\u6216\u8005\u4e0d\u5728\uff08!in\uff09\u4e00\u4e2a\u533a\u95f4\u6216\u8005\u96c6\u5408\u4e2d\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">when (x) {\n    in 1..10 -&gt; print(\"x is in the range\")\n    in validNumbers -&gt; print(\"x is valid\")\n    !in 10..20 -&gt; print(\"x is outside the range\")\n    else -&gt; print(\"none of the above\")\n}<\/code><\/pre>\n\n\n\n<p>\u53e6\u4e00\u79cd\u53ef\u80fd\u6027\u662f\u68c0\u6d4b\u4e00\u4e2a\u503c\u662f\uff08is\uff09\u6216\u8005\u4e0d\u662f\uff08!is\uff09\u4e00\u4e2a\u7279\u5b9a\u7c7b\u578b\u7684\u503c\u3002\u6ce8\u610f\uff1a \u7531\u4e8e\u667a\u80fd\u8f6c\u6362\uff0c\u4f60\u53ef\u4ee5\u8bbf\u95ee\u8be5\u7c7b\u578b\u7684\u65b9\u6cd5\u548c\u5c5e\u6027\u800c\u65e0\u9700\u4efb\u4f55\u989d\u5916\u7684\u68c0\u6d4b\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">fun hasPrefix(x: Any) = when(x) {\n    is String -&gt; x.startsWith(\"prefix\")\n    else -&gt; false\n}<\/code><\/pre>\n\n\n\n<p>when \u4e5f\u53ef\u4ee5\u7528\u6765\u53d6\u4ee3 if-else if\u94fe\u3002 \u5982\u679c\u4e0d\u63d0\u4f9b\u53c2\u6570\uff0c\u6240\u6709\u7684\u5206\u652f\u6761\u4ef6\u90fd\u662f\u7b80\u5355\u7684\u5e03\u5c14\u8868\u8fbe\u5f0f\uff0c\u800c\u5f53\u4e00\u4e2a\u5206\u652f\u7684\u6761\u4ef6\u4e3a\u771f\u65f6\u5219\u6267\u884c\u8be5\u5206\u652f\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">when {\n    x.isOdd() -&gt; print(\"x is odd\")\n    x.isEven() -&gt; print(\"x is even\")\n    else -&gt; print(\"x is funny\")\n}<\/code><\/pre>\n\n\n\n<h1 class=\"wp-block-heading\">7.\u53bb\u4f60\u7684ClassCastException<\/h1>\n\n\n\n<h2 class=\"wp-block-heading\">Kotlin\u667a\u80fd\u8f6c\u6362(Smart Casts)<\/h2>\n\n\n\n<p>\u5bf9\u4e8e\u4e0d\u53ef\u53d8\u7684\u503c,Kotlin\u4e00\u822c\u4e0d\u9700\u8981\u663e\u5f0f\u8f6c\u6362\u5bf9\u8c61\u7c7b\u578b,\u7f16\u8bd1\u5668\u80fd\u8ddf\u8e2ais\u68c0\u67e5\u7c7b\u578b,\u5728\u9700\u8981\u65f6\u4f1a\u81ea\u52a8\u63d2\u5165\u7c7b\u578b\u8f6c\u6362\u4ee3\u7801(\u5b89\u5168):<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">fun classCast(a: Any) {\n    if (a is String) {\n        print(a.length) \/\/\u7f16\u8bd1\u5668\u81ea\u52a8\u628aa\u8f6c\u6362\u4e3aString\u7c7b\u578b\n    }\n}<\/code><\/pre>\n\n\n\n<p>Kotlin\u7f16\u8bd1\u5668\u5f88\u806a\u660e,\u80fd\u8bc6\u522b\u53cd\u5411\u68c0\u67e5\u7c7b\u578b!is\u64cd\u4f5c\u7b26,\u4f1a\u81ea\u52a8\u63d2\u5165\u7c7b\u578b\u8f6c\u6362\u4ee3\u7801\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">if (a !is String) return\nprint(a.length) \/\/\u7f16\u8bd1\u5668\u81ea\u52a8\u628ax\u8f6c\u6362\u4e3aString\u7c7b\u578b\uff1a\n\/\/ ||\u53f3\u4fa7, a\u81ea\u52a8\u8f6c\u6362\u4e3aString\u7c7b\u578b\nif (a !is String || a.length == 0) return\n\/\/ &amp;&amp;\u53f3\u4fa7, a\u81ea\u52a8\u8f6c\u6362\u4e3aString\u7c7b\u578b\nif (a is String &amp;&amp; a.length > 0) {\n    print(a.length) \/\/ a \u81ea\u52a8\u8f6c\u6362\u4e3a\u5b57\u7b26\u4e32\n}\n\/\/\u667a\u80fd\u8f6c\u6362(smart casts)\u4e5f\u7528\u4e8ewhen\u8868\u8fbe\u5f0f\u548cwhile\u5faa\u73af\nwhen (a) {\n    is Int -> print(a + 1)\n    is String -> print(a.length + 1)\n    is IntArray -> print(a.sum())\n}<\/code><\/pre>\n\n\n\n<p>\u5982\u679c\u4e0d\u80fd\u4fdd\u8bc1\u53d8\u91cf\u5728\u7c7b\u578b\u68c0\u67e5<code>is<\/code>\/<code>!is<\/code>\u64cd\u4f5c\u7b26\u548c\u53d8\u91cf\u4f7f\u7528\u4e4b\u95f4\u4e0d\u53ef\u6539\u53d8\u65f6,\u667a\u80fd\u8f6c\u6362\u4e0d\u80fd\u7528\u3002\u667a\u80fd\u8f6c\u6362\u7684\u9002\u7528\u6761\u4ef6\u6216\u89c4\u5219:<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>val\u5c40\u90e8\u53d8\u91cf-\u603b\u662f\u9002\u7528!<\/li><li>val\u5c5e\u6027-\u9002\u7528\u4e8eprivate\u6216internal,\u6216\u8005\u7c7b\u578b\u68c0\u67e5is\/!is\u5728\u58f0\u660e\u5c5e\u6027\u7684\u540c\u4e00\u6a21\u5757\u4e2d\u6267\u884c;<\/li><li>\u4e0d\u9002\u7528\u4e8eopen\u7684\u5c5e\u6027,\u6216\u8005\u5177\u6709\u81ea\u5b9a\u4e49getter\u7684\u5c5e\u6027!<\/li><li>var\u5c40\u90e8\u53d8\u91cf\u2014\u9002\u7528\u4e8e\u53d8\u91cf\u5728\u7c7b\u578b\u68c0\u67e5\u548c\u4f7f\u7528\u4e4b\u95f4\u6ca1\u6709\u4fee\u6539,\u4e14\u4e0d\u5728\u4fee\u6539\u5b83\u7684lambda\u4e2d\u6355\u83b7!<\/li><li>var\u5c5e\u6027-\u4e0d\u9002\u7528(\u56e0\u4e3a\u8be5\u53d8\u91cf\u53ef\u968f\u65f6\u88ab\u4fee\u6539)<\/li><\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">\u5b89\u5168(\u53ef\u7a7a)\u8f6c\u6362-\u64cd\u4f5c\u7b26as?<\/h2>\n\n\n\n<p>\u4e3a\u907f\u514d\u629b\u51fa\u5f02\u5e38,\u53ef\u7528\u5b89\u5168\u8f6c\u6362\u64cd\u4f5c\u7b26<code>as?<\/code>,\u5728\u5931\u8d25\u65f6\u8fd4\u56denull<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">val a: String? = b as? String<\/code><\/pre>\n\n\n\n<p>\u5c3d\u7ba1<code>as?<\/code>\u53f3\u8fb9\u662f\u4e00\u4e2a\u975e\u7a7a\u7c7b\u578bString,\u4f46\u662f<code>as?<\/code>\u8f6c\u6362\u5931\u8d25\u65f6\u8fd4\u56de\u53ef\u7a7a(null)\uff0c\u6362\u53e5\u8bdd\u8bf4\u5c31\u662f,<code>as?<\/code>\u51fd\u6570\u53c2\u6570String\u4e0d\u80fd\u4e3anull,\u4f46\u662fas?\u51fd\u6570\u7684\u8fd4\u56de\u503c\u53ef\u4ee5\u662fnull<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">8.\u771f\u7684\u8981\u4e60\u60efKoltin\u7684for\u5faa\u73af\uff0c\u592a\u5f3a\u5927\u4e86<\/h1>\n\n\n\n<p>Kotlin\u6ca1\u6709Java\u4e2d\u7684for(\u521d\u59cb\u503c;\u6761\u4ef6\uff1b\u589e\u51cf\u6b65\u957f)\u8fd9\u4e2a\u89c4\u5219\u3002\u4f46\u662fKotlin\u4e2d\u5bf9\u4e8efor\u5faa\u73af\u8bed\u53e5\u65b0\u589e\u4e86\u5176\u4ed6\u7684\u89c4\u5219\uff0c\u6765\u6ee1\u8db3\u521a\u63d0\u5230\u7684\u89c4\u5219\u3002<\/p>\n\n\n\n<ul class=\"wp-block-list\"><li>for\u5faa\u73af\u63d0\u4f9b\u8fed\u4ee3\u5668\u7528\u6765\u904d\u5386\u4efb\u4f55\u4e1c\u897f<\/li><li>for\u5faa\u73af\u6570\u7ec4\u88ab\u7f16\u8bd1\u4e3a\u4e00\u4e2a\u57fa\u4e8e\u7d22\u5f15\u7684\u5faa\u73af\uff0c\u5b83\u4e0d\u4f1a\u521b\u5efa\u4e00\u4e2a\u8fed\u4ee3\u5668\u5bf9\u8c61<\/li><\/ul>\n\n\n\n<h2 class=\"wp-block-heading\">\u65b0\u589e\u7684\u89c4\u5219\uff0c\u53bb\u6ee1\u8db3for(\u521d\u59cb\u503c;\u6761\u4ef6;\u589e\u51cf\u6b65\u957f)\u8fd9\u4e2a\u89c4\u5219<\/h2>\n\n\n\n<h3 class=\"wp-block-heading\">\u9012\u589e<\/h3>\n\n\n\n<p>\u5173\u952e\u5b57\uff1auntil<br>\u8303\u56f4\uff1auntil[n,m) =&gt; \u5373\u5927\u4e8e\u7b49\u4e8en,\u5c0f\u4e8em<\/p>\n\n\n\n<p>\u4f8b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">\/\/ \u5faa\u73af5\u6b21\uff0c\u4e14\u6b65\u957f\u4e3a1\u7684\u9012\u589e\nfor (i in 0 until 5){\n  print(\"i =&gt; $i \\t\")\n}<\/code><\/pre>\n\n\n\n<p>\u8f93\u51fa\u7ed3\u679c\u4e3a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">i =&gt; 0  i =&gt; 1  i =&gt; 2  i =&gt; 3  i =&gt; 4<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u9012\u51cf<\/h3>\n\n\n\n<p>\u5173\u952e\u5b57\uff1adownTo<br>\u8303\u56f4\uff1adownTo[n,m] =&gt; \u5373\u5c0f\u4e8e\u7b49\u4e8en,\u5927\u4e8e\u7b49\u4e8em ,n &gt; m<br>\u4f8b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">\/\/ \u5faa\u73af5\u6b21\uff0c\u4e14\u6b65\u957f\u4e3a1\u7684\u9012\u51cf\nfor (i in 15 downTo 11){\n    print(\"i =&gt; $i \\t\")\n}<\/code><\/pre>\n\n\n\n<p>\u8f93\u51fa\u7ed3\u679c\u4e3a\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code class=\"\">i =&gt; 15     i =&gt; 14     i =&gt; 13     i =&gt; 12     i =&gt; 11<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u7b26\u53f7\uff08\u2019 .. \u2018\uff09 \u8868\u793a\u9012\u589e\u7684\u5faa\u73af\u7684\u53e6\u5916\u4e00\u79cd\u64cd\u4f5c<\/h3>\n\n\n\n<p>\u4f7f\u7528\u7b26\u53f7( \u2018..\u2019).<br>\u8303\u56f4\uff1a..[n,m]=&gt; \u5373\u5927\u4e8e\u7b49\u4e8en\uff0c\u5c0f\u4e8e\u7b49\u4e8em<br>\u548cuntil\u7684\u533a\u522b\uff0c\u4e00\u662f\u7b80\u4fbf\u6027\u3002\u4e8c\u662f\u8303\u56f4\u7684\u4e0d\u540c\u3002<br>\u4f8b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">print(\"\u4f7f\u7528 \u7b26\u53f7`..`\u7684\u6253\u5370\u7ed3\u679c\\n\")\nfor (i in 20 .. 25){\n    print(\"i =&gt; $i \\t\")\n}\nprintln()\nprint(\"\u4f7f\u7528until\u7684\u6253\u5370\u7ed3\u679c\\n\")\nfor (i in 20 until 25){\n    print(\"i =&gt; $i \\t\")\n}<\/code><\/pre>\n\n\n\n<p>\u8f93\u51fa\u7ed3\u679c\u4e3a\uff1a<\/p>\n\n\n\n<p>\u4f7f\u7528 \u7b26\u53f7<code>..<\/code>\u7684\u6253\u5370\u7ed3\u679c<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code class=\"\">i =&gt; 20     i =&gt; 21     i =&gt; 22     i =&gt; 23     i =&gt; 24     i =&gt; 25<\/code><\/pre>\n\n\n\n<p>\u4f7f\u7528until\u7684\u6253\u5370\u7ed3\u679c<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code class=\"\">i =&gt; 20     i =&gt; 21     i =&gt; 22     i =&gt; 23     i =&gt; 24<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u8bbe\u7f6e\u6b65\u957f<\/h3>\n\n\n\n<p>\u5173\u952e\u5b57\uff1astep<\/p>\n\n\n\n<p>\u4f8b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">for (i in 10 until 16 step 2){\n    print(\"i =&gt; $i \\t\")\n}<\/code><\/pre>\n\n\n\n<p>\u8f93\u51fa\u7ed3\u679c\u4e3a\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code class=\" line-numbers\">i =&gt; 10     i =&gt; 12     i =&gt; 14<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u8fed\u4ee3<\/h3>\n\n\n\n<p>for\u5faa\u73af\u63d0\u4f9b\u4e00\u4e2a\u8fed\u4ee3\u5668\u7528\u6765\u904d\u5386\u4efb\u4f55\u4e1c\u897f\u3002<br>for\u5faa\u73af\u6570\u7ec4\u88ab\u7f16\u8bd1\u4e3a\u4e00\u4e2a\u57fa\u4e8e\u7d22\u5f15\u7684\u5faa\u73af\uff0c\u5b83\u4e0d\u4f1a\u521b\u5efa\u4e00\u4e2a\u8fed\u4ee3\u5668\u5bf9\u8c61<\/p>\n\n\n\n<h3 class=\"wp-block-heading\">\u904d\u5386\u5b57\u7b26\u4e32<\/h3>\n\n\n\n<p>\u6b64\u7528\u6cd5\u5728\u6570\u636e\u7c7b\u578b\u7ae0\u8282\u4e2d\u7684\u5b57\u7b26\u4e32\u7c7b\u578b\u4e2d\u7528\u5230\u8fc7\u3002\u8fd8\u4e0d\u751a\u6e05\u695a\u7684\u53ef\u4ee5\u67e5\u770b Kotlin\u2014\u2014\u6700\u8be6\u7ec6\u7684\u6570\u636e\u7c7b\u578b\u4ecb\u7ecd\u3002<\/p>\n\n\n\n<p>\u4f8b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">for (i in \"abcdefg\"){\n    print(\"i =&gt; $i \\t\")\n}<\/code><\/pre>\n\n\n\n<p>\u8f93\u51fa\u7ed3\u679c\u4e3a\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"\" class=\" line-numbers\">i =&gt; a  i =&gt; b  i =&gt; c  i =&gt; d  i =&gt; e  i =&gt; f  i =&gt; g<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u904d\u5386\u6570\u7ec4<\/h3>\n\n\n\n<p>\u6b64\u7528\u6cd5\u5728\u6570\u636e\u7c7b\u578b\u7ae0\u8282\u4e2d\u7684\u6570\u7ec4\u7c7b\u578b\u4e2d\u7528\u5230\u8fc7\u3002\u8fd8\u4e0d\u751a\u6e05\u695a\u7684\u53ef\u4ee5\u67e5\u770b Kotlin\u2014\u2014\u6700\u8be6\u7ec6\u7684\u6570\u636e\u7c7b\u578b\u4ecb\u7ecd\u3002<\/p>\n\n\n\n<p>\u4f8b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">var arrayListOne = arrayOf(10,20,30,40,50)\nfor (i in arrayListOne){\n    print(\"i =&gt; $i \\t\")\n}<\/code><\/pre>\n\n\n\n<p>\u8f93\u51fa\u7ed3\u679c\u4e3a\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code class=\" line-numbers\">i =&gt; 10     i =&gt; 20     i =&gt; 30     i =&gt; 40     i =&gt; 50<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u4f7f\u7528\u6570\u7ec4\u7684indices\u5c5e\u6027\u904d\u5386<\/h3>\n\n\n\n<p>\u4f8b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">var arrayListTwo = arrayOf(1,3,5,7,9)\nfor (i in arrayListTwo.indices){\n    println(\"arrayListTwo[$i] =&gt; \" + arrayListTwo[i])\n}<\/code><\/pre>\n\n\n\n<p>\u8f93\u51fa\u7ed3\u679c\u4e3a\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code class=\" line-numbers\">arrayListTwo[0] =&gt; 1\narrayListTwo[1] =&gt; 3\narrayListTwo[2] =&gt; 5\narrayListTwo[3] =&gt; 7\narrayListTwo[4] =&gt; 9<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u4f7f\u7528\u6570\u7ec4\u7684withIndex()\u65b9\u6cd5\u904d\u5386<\/h3>\n\n\n\n<p>\u4f8b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">var arrayListTwo = arrayOf(1,3,5,7,9)\nfor ((index,value) in arrayListTwo.withIndex()){\n    println(\"index =&gt; $index \\t value =&gt; $value\")\n}<\/code><\/pre>\n\n\n\n<p>\u8f93\u51fa\u7ed3\u679c\u4e3a\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code class=\" line-numbers\">index =&gt; 0   value =&gt; 1\nindex =&gt; 1   value =&gt; 3\nindex =&gt; 2   value =&gt; 5\nindex =&gt; 3   value =&gt; 7\nindex =&gt; 4   value =&gt; 9<\/code><\/pre>\n\n\n\n<h3 class=\"wp-block-heading\">\u4f7f\u7528\u5217\u8868\u6216\u6570\u7ec4\u7684\u6269\u5c55\u51fd\u6570\u904d\u5386<\/h3>\n\n\n\n<p>\u6570\u7ec4\u6216\u5217\u8868\u6709\u4e00\u4e2a\u6210\u5458\u6216\u6269\u5c55\u51fd\u6570iterator()\u5b9e\u73b0\u4e86Iterator\u63a5\u53e3\uff0c\u4e14\u8be5\u63a5\u53e3\u63d0\u4f9b\u4e86next()\u4e0ehasNext()\u4e24\u4e2a\u6210\u5458\u6216\u6269\u5c55\u51fd\u6570<br>\u5176\u4e00\u822c\u548cwhile\u5faa\u73af\u4e00\u8d77\u4f7f\u7528<br>\u53ef\u4ee5\u67e5\u770bArray.kt\u8fd9\u4e2a\u7c7b\u3002\u53ef\u4ee5\u770b\u89c1\u5176\u4e2d\u7684iterator()\u51fd\u6570\uff0c\u800c\u8fd9\u4e2a\u51fd\u6570\u5b9e\u73b0\u4e86Iterator\u63a5\u53e3\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">\/**\n  *   Creates an iterator for iterating over the elements of the array.\n  *\/\npublic operator fun iterator(): Iterator&lt;T&gt;<\/code><\/pre>\n\n\n\n<p>\u67e5\u770bIterator.kt\u8fd9\u4e2a\u63a5\u53e3\u7c7b\uff0c\u8fd9\u4e2a\u63a5\u53e3\u63d0\u4f9b\u4e86hasNext()\u51fd\u6570\u548cnext()\u51fd\u6570\u3002<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">public interface Iterator&lt;out T&gt; {\n\/**\n  * Returns the next element in the iteration.\n  *\/\npublic operator fun next(): T\n\/**\n  * Returns `true` if the iteration has more elements.\n  *\/\npublic operator fun hasNext(): Boolean\n}<\/code><\/pre>\n\n\n\n<p>\u4f8b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">var arrayListThree = arrayOf(2,'a',3,false,9)\nvar iterator: Iterator&lt;Any&gt; = arrayListThree.iterator()\nwhile (iterator.hasNext()){\n    println(iterator.next())\n}<\/code><\/pre>\n\n\n\n<p>\u8f93\u51fa\u7ed3\u679c\u4e3a\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code class=\" line-numbers\">2\na\n3\nfalse\n9<\/code><\/pre>\n\n\n\n<p>\u5173\u4e8efor\u5faa\u73af\u7684\u5185\u5bb9\u6765\u81ea<a href=\"http:\/\/codebay.cn\/post\/8088.html\" target=\"_blank\" rel=\"noreferrer noopener\">\u300aKotlin\u2014\u2014\u6700\u8be6\u7ec6\u7684\u63a7\u5236\u8bed\u53e5\u8be6\u89e3\u300b<\/a><\/p>\n\n\n\n<h1 class=\"wp-block-heading\">9.kotlin stream \u771f\u5fc3\u53ef\u4ee5<\/h1>\n\n\n\n<p>\u6d41\u5f0f\u5904\u7406\u7ed9\u6211\u4eec\u7684\u96c6\u5408\u64cd\u4f5c\u5e26\u6765\u4e86\u5f88\u5927\u7684\u65b9\u4fbf\uff0c\u5176\u5b9eJava 8 \u4e00\u6837\u652f\u6301\u6d41\u5f0f\u5904\u7406\uff0c\u6211\u53ea\u662f\u60f3\u5728\u8fd9\u91cc\u63a8\u5e7f\u4e00\u4e0b stream\u3002<\/p>\n\n\n\n<p>\u4e0b\u9762\u4e3e\u4f8b\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">val names = arrayOf(\"Amy\", \"Alex\", \"Bob\", \"Cindy\", \"Jeff\", \"Jack\", \"Sunny\", \"Sara\", \"Steven\")  \n  \n\/\/\u7b5b\u9009S\u5f00\u5934\u7684\u4eba\u540d  \nval sName = names.filter { it.startsWith(\"S\") }.toList()  \n  \n\/\/\u6309\u9996\u5b57\u6bcd\u5206\u7ec4\u5e76\u6392\u5e8f  \nval nameGroup = names.groupBy { it[0] }  \n        .toSortedMap( Comparator { key1, key2 -&gt; key1.compareTo(key2) })<\/code><\/pre>\n\n\n\n<p>\u5173\u4e8e\u66f4\u591a\u6d41\u5f0f\u5904\u7406\uff0c\u8bf7\u81ea\u884c\u641c\u7d22Java stream<\/p>\n\n\n\n<h1 class=\"wp-block-heading\">10.\u5c11\u5199\u70b9\u65b9\u6cd5\u91cd\u8f7d<\/h1>\n\n\n\n<p>\u56e0\u4e3akotlin\u652f\u6301\u9ed8\u8ba4\u53c2\u6570\uff0c\u6240\u4ee5\u5728\u5c01\u88c5\u65b9\u6cd5\u65f6\u4f1a\u5c11\u5f88\u591a\u7684\u65b9\u6cd5\u91cd\u8f7d\u7684\u3002<\/p>\n\n\n\n<p>\u5982\u679c\u6ca1\u6709\u9ed8\u8ba4\u53c2\u6570\u7684\u9700\u8981\u5b9e\u73b0\u4e0b\u9762\u7684\u65e5\u5fd7\u6253\u5370\uff0c\u9700\u8981\u5199\u591a\u4e2a\u65b9\u6cd5\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">fun log(tag: String, content: String) {\n    println(\"tag:$tag--&gt;$content\")\n}\nfun log( content: String) {\n    log(\"quanke\",\"\")\n}<\/code><\/pre>\n\n\n\n<p>\u4f7f\u7528\u9ed8\u8ba4\u53c2\u6570\u53ea\u9700\u8981\u4e00\u4e2a\u65b9\u6cd5\uff1a<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code lang=\"kotlin\" class=\"language-kotlin line-numbers\">fun log(tag: String=\"quanke\", content: String) {\n    println(\"tag:$tag--&gt;$content\")\n}<\/code><\/pre>\n\n\n\n<p>\u6700\u540e\u6211\u8fd8\u662f\u60f3\u8bf4\uff1a\u62b1\u6b49\uff01\u4e0d\u8981\u7528Java\u7684\u8bed\u6cd5\u601d\u7ef4\u6765\u5199Kotlin\uff01<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u4f5c\u8005\uff1alnbnuaa \u4f86\u6e90\uff1ahttps:\/\/www.open-open.com\/lib\/view\/open15 &hellip; <\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[2],"tags":[32,33],"class_list":["post-1089","post","type-post","status-publish","format-standard","hentry","category-2","tag-32","tag-33"],"_links":{"self":[{"href":"https:\/\/blog.ray650128.com\/index.php?rest_route=\/wp\/v2\/posts\/1089","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/blog.ray650128.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/blog.ray650128.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/blog.ray650128.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/blog.ray650128.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1089"}],"version-history":[{"count":2,"href":"https:\/\/blog.ray650128.com\/index.php?rest_route=\/wp\/v2\/posts\/1089\/revisions"}],"predecessor-version":[{"id":1092,"href":"https:\/\/blog.ray650128.com\/index.php?rest_route=\/wp\/v2\/posts\/1089\/revisions\/1092"}],"wp:attachment":[{"href":"https:\/\/blog.ray650128.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1089"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/blog.ray650128.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=1089"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/blog.ray650128.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=1089"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}