{"id":3994,"date":"2018-06-16T17:14:07","date_gmt":"2018-06-16T09:14:07","guid":{"rendered":"https:\/\/ixyzero.com\/blog\/?p=3994"},"modified":"2018-06-16T17:14:07","modified_gmt":"2018-06-16T09:14:07","slug":"java%e4%b8%ad%e7%9a%84%e4%b8%80%e4%ba%9b%e5%9f%ba%e7%a1%80%e4%bb%a3%e7%a0%81%e7%89%87%e6%ae%b5_4","status":"publish","type":"post","link":"https:\/\/ixyzero.com\/blog\/archives\/3994.html","title":{"rendered":"Java\u4e2d\u7684\u4e00\u4e9b\u57fa\u7840\u4ee3\u7801\u7247\u6bb5_4"},"content":{"rendered":"<p>=Start=<\/p>\n<h4 id=\"id-\u6a21\u677f-\u7f18\u7531\uff1a\">\u7f18\u7531\uff1a<\/h4>\n<p>\u5728\u5b66\u4e60Java\u7684\u8fc7\u7a0b\u4e2d\u4e0d\u65ad\u7528\u6587\u7ae0\u8fdb\u884c\u6574\u7406\u603b\u7ed3\uff08\u5e38\u7528\u529f\u80fd\u7684Java\u5b9e\u73b0\uff09\uff0c\u4e89\u53d6\u65e9\u65e5\u80fd\u8f83\u4e3a\u719f\u7ec3\u7684\u4f7f\u7528Java\u8fdb\u884c\u5f00\u53d1\u3002<\/p>\n<p>\u8fd9\u4e00\u7bc7\u4e3b\u8981\u662f\u5bf9Java\u6742\u9879\u77e5\u8bc6\u7684\u4e00\u4e2a\u6574\u7406\u548c\u603b\u7ed3\u3002<\/p>\n<h4 id=\"id-\u6a21\u677f-\u6b63\u6587\uff1a\">\u6b63\u6587\uff1a<\/h4>\n<h5 id=\"id-\u6a21\u677f-\u53c2\u8003\u89e3\u7b54\uff1a\">\u53c2\u8003\u89e3\u7b54\uff1a<\/h5>\n<h6><span style=\"color: #ff0000;\"><strong>1. \u4e09\u5143\u64cd\u4f5c\u7b26\uff1b<\/strong><\/span><\/h6>\n<pre class=\"lang:default decode:true\">package com.ixyzero.learn.misc;\r\n\r\n\/**\r\n * (\u6761\u4ef6\u8868\u8fbe\u5f0f) ? \u8868\u8fbe\u5f0f1 : \u8868\u8fbe\u5f0f2;\r\n * \u5f53 (\u6761\u4ef6\u8868\u8fbe\u5f0f) \u4e3a True \u65f6, \u6267\u884c \u8868\u8fbe\u5f0f1 ; \u4e3a False \u65f6,\u6267\u884c \u8868\u8fbe\u5f0f2 \u3002\r\n *\/\r\npublic class TestTernaryOperator {\r\n    public static void main(String[] args) {\r\n        int a = 1;\r\n        int b = 5;\r\n        System.out.println(\"a = \" + a + \"\\nb = \" + b);\r\n        int c;\r\n        c = (\"\" == null || true != false) ? a : b;\r\n        System.out.println(\"\\nc = \" + c);\r\n\r\n        System.out.println();\r\n        System.out.println(\"'\\\"\\\" == null' is \" + (\"\" == null));\r\n        System.out.println(\"'true != false' is \" + (true != false));\r\n    }\r\n}<\/pre>\n<h6><span style=\"color: #ff0000;\"><strong>2. static \u8bed\u53e5\u5757\u7684\u521d\u59cb\u5316\u987a\u5e8f\uff1b<\/strong><\/span><\/h6>\n<pre class=\"lang:default decode:true\">package com.ixyzero.learn.misc;\r\n\r\n\/**\r\n * Java\u91cc\u9762\u4e00\u4e2aclass\u5b83\u7684\u521d\u59cb\u5316\u987a\u5e8f\u662f\uff1f\r\n    \u5148 static \u518d init \u5462\uff1f\u8fd8\u662f\u76f4\u63a5 init \u5462\uff1f\r\n    \u7ed3\u8bba\uff1a\r\n    \u5148 static \u518d main\/init \u3002\r\n *\r\nprint in class static code block\r\nprint in main method\r\nprint in class init method\r\nhello\r\n *\r\n *\/\r\npublic class TestStatic {\r\n\r\n    static {\r\n        System.out.println(\"print in class static code block\");\r\n    }\r\n\r\n    private TestStatic() {\r\n        System.out.println(\"print in class init method\");\r\n    }\r\n    private void hello() {\r\n        System.out.println(\"hello\");\r\n    }\r\n\r\n    public static void main(String[] args) {\r\n        System.out.println(\"print in main method\");\r\n\r\n        TestStatic testStatic = new TestStatic();\r\n        testStatic.hello();\r\n    }\r\n}<\/pre>\n<h6><strong>3. \u5feb\u901f\u6253\u5370\u5f53\u524d\u65e5\u671f\u65f6\u95f4\u7684\u65b9\u5f0f\uff1b<\/strong><\/h6>\n<pre class=\"lang:default decode:true \">package com.ixyzero.learn.misc;\r\n\r\nimport java.text.SimpleDateFormat;\r\n\r\npublic class TestSubstring {\r\n    public static void main(String[] args) {\r\n        SimpleDateFormat df = new SimpleDateFormat(\"yyyy-MM-dd HH:mm:ss\");\r\n        String currentDateTime = df.format(System.currentTimeMillis());\r\n\r\n        System.out.println(df.toString()); \/\/ java.text.SimpleDateFormat@4f76f1a0\r\n        System.out.println(currentDateTime); \/\/ 2018-06-16 16:56:32\r\n    }\r\n}<\/pre>\n<h6><strong>4. \u7c7b\u578b\u8f6c\u6362\u7684\u4e00\u4e9b\u60c5\u5f62\u603b\u7ed3\uff1b<\/strong><\/h6>\n<pre class=\"lang:default decode:true\">package com.ixyzero.learn.misc;\r\n\r\npublic class TestConvert {\r\n    private static Object returnType() {\r\n        return true;\r\n        \/\/ return \"haha\"; \/\/ java.lang.ClassCastException: java.lang.String cannot be cast to java.lang.Boolean\r\n    }\r\n\r\n    private static Object returnType2() {\r\n        \/\/ return true; \/\/ java.lang.ClassCastException: java.lang.Boolean cannot be cast to java.lang.String\r\n        return \"\";\r\n    }\r\n\r\n    public static void main(String[] args) {\r\n        boolean tag = (Boolean) returnType();\r\n        if (tag) {\r\n            System.out.println(\"tag is '\" + tag + \"'\");\r\n        } else {\r\n            System.out.println(\"tag is '\" + tag + \"'\");\r\n        }\r\n\r\n        String tagStr = (String) returnType2();\r\n        if (tagStr  != null &amp;&amp; !tagStr.isEmpty()) {\r\n            System.out.println(\"tagStr is '\" + tagStr + \"'\");\r\n        } else {\r\n            System.out.println(\"tagStr is '\" + tagStr + \"'\");\r\n        }\r\n    }\r\n}<\/pre>\n<h6><strong>5. \u83b7\u53d6\u4e3b\u673a\u540d\u7684\u65b9\u6cd5\uff1b<\/strong><\/h6>\n<pre class=\"lang:default decode:true \">package com.ixyzero.learn.misc;\r\n\r\nimport java.io.IOException;\r\nimport java.net.InetAddress;\r\nimport java.net.UnknownHostException;\r\nimport java.util.Scanner;\r\n\r\npublic class TestgetHostName {\r\n    public static void main(String[] args) {\r\n        String hostname = null;\r\n        try {\r\n            hostname = InetAddress.getLocalHost().getHostName();\r\n        } catch (UnknownHostException e) {\r\n            e.printStackTrace();\r\n        }\r\n        System.out.println(\"InetAddress.getLocalHost().getHostName() = \" + hostname);\r\n\r\n        String os = System.getProperty(\"os.name\").toLowerCase();\r\n        System.out.println(\"String os = System.getProperty(\\\"os.name\\\").toLowerCase() = \" + os);\r\n        if (os.contains(\"win\")) {\r\n            try {\r\n                System.out.println(\"Windows computer name through env:\\\"\" + System.getenv(\"COMPUTERNAME\") + \"\\\"\");\r\n                System.out.println(\"Windows computer name through exec:\\\"\" + execReadToString(\"hostname\") + \"\\\"\");\r\n            } catch (IOException e) {\r\n                e.printStackTrace();\r\n            }\r\n        } else if (os.contains(\"nix\") || os.contains(\"nux\") || os.contains(\"mac os x\")) {\r\n            try {\r\n                System.out.println(\"Unix-like computer name through env:\\\"\" + System.getenv(\"HOSTNAME\") + \"\\\"\");\r\n                System.out.println(\"Unix-like computer name through exec:\\\"\" + execReadToString(\"hostname\") + \"\\\"\");\r\n                System.out.println(\"Unix-like computer name through \/etc\/hostname:\\\"\" + execReadToString(\"cat \/etc\/hostname\") + \"\\\"\");\r\n            } catch (IOException e) {\r\n                e.printStackTrace();\r\n            }\r\n        }\r\n    }\r\n\r\n    public static String execReadToString(String execCommand) throws IOException {\r\n        try (Scanner s = new Scanner(Runtime.getRuntime().exec(execCommand).getInputStream()).useDelimiter(\"\\\\A\")) {\r\n            return s.hasNext() ? s.next() : \"\";\r\n        }\r\n    }\r\n\r\n}\r\n<\/pre>\n<p>&nbsp;<\/p>\n<h5 id=\"id-\u6a21\u677f-\u53c2\u8003\u94fe\u63a5\uff1a\">\u53c2\u8003\u94fe\u63a5\uff1a<\/h5>\n<ul>\n<li><a href=\"https:\/\/blog.csdn.net\/wlj323\/article\/details\/50760550\">\u3010Java\u3011(\u4e09)\u8fd0\u7b97\u7b26\u5c0f\u7ed3(\u6bd4\u8f83\u3001\u903b\u8f91\u3001\u4e09\u5143\u8fd0\u7b97\u7b26)<\/a><\/li>\n<li><a href=\"https:\/\/www.cnblogs.com\/twlqx\/p\/4430135.html\">java \u9759\u6001\u4ee3\u7801\u5757\u6267\u884c\u987a\u5e8f<\/a><\/li>\n<li><a href=\"https:\/\/www.cnblogs.com\/panjun-Donet\/archive\/2010\/08\/10\/1796209.html\">java\u4e2d\u9759\u6001\u4ee3\u7801\u5757\u7684\u7528\u6cd5 static\u7528\u6cd5\u8be6\u89e3<\/a><\/li>\n<li><a href=\"https:\/\/stackoverflow.com\/questions\/7348711\/recommended-way-to-get-hostname-in-java\">Recommended way to get hostname in Java<\/a><\/li>\n<\/ul>\n<p>=END=<\/p>\n","protected":false},"excerpt":{"rendered":"<p>=Start= \u7f18\u7531\uff1a \u5728\u5b66\u4e60Java\u7684\u8fc7\u7a0b\u4e2d\u4e0d\u65ad\u7528\u6587\u7ae0\u8fdb\u884c\u6574\u7406\u603b\u7ed3\uff08\u5e38\u7528\u529f\u80fd\u7684Java\u5b9e\u73b0\uff09\uff0c\u4e89\u53d6\u65e9\u65e5\u80fd\u8f83\u4e3a [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[23,7],"tags":[942,61,1161],"class_list":["post-3994","post","type-post","status-publish","format-standard","hentry","category-knowledgebase-2","category-programing","tag-static","tag-java","tag-1161"],"views":6354,"_links":{"self":[{"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/posts\/3994","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/comments?post=3994"}],"version-history":[{"count":1,"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/posts\/3994\/revisions"}],"predecessor-version":[{"id":3995,"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/posts\/3994\/revisions\/3995"}],"wp:attachment":[{"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/media?parent=3994"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/categories?post=3994"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/ixyzero.com\/blog\/wp-json\/wp\/v2\/tags?post=3994"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}