{"id":128,"date":"2020-11-23T17:01:58","date_gmt":"2020-11-23T09:01:58","guid":{"rendered":"https:\/\/refusea.com\/?p=128"},"modified":"2020-12-20T20:36:33","modified_gmt":"2020-12-20T12:36:33","slug":"java-%e6%b3%9b%e5%9e%8b%e5%8f%82%e6%95%b0%e4%b8%ad%e9%80%9a%e9%85%8d%e7%ac%a6-%e5%92%8c-object-%e7%9a%84%e5%b7%ae%e5%bc%82","status":"publish","type":"post","link":"https:\/\/refusea.com\/?p=128","title":{"rendered":"Java \u6cdb\u578b\u53c2\u6570\u4e2d\u901a\u914d\u7b26 ? \u548c Object \u7684\u5dee\u5f02"},"content":{"rendered":"<h2>\u6982\u8ff0<\/h2>\n<p>\u9762\u5411\u5bf9\u8c61\u7684\u8bbe\u8ba1\u6709\u4e2a\u57fa\u672c\u539f\u5219\uff1a\u91cc\u6c0f\u4ee3\u6362\u539f\u5219\uff0c\u7b80\u5355\u7406\u89e3\u4e3a\u51e1\u662f\u63a5\u53d7\u7236\u7c7b\u7684\u573a\u5408\uff0c\u90fd\u53ef\u4ee5\u63a5\u53d7\u5176\u5b50\u7c7b\u3002<\/p>\n<p>Java \u662f\u4e00\u79cd\u9762\u5411\u5bf9\u8c61\u7684\u8bed\u8a00\uff0c\u4e5f\u8bb8\u5f88\u591a\u540c\u5b66\u5e76\u6ca1\u6709\u542c\u8bf4\u8fc7\u6240\u8c13\u7684\u91cc\u6c0f\u4ee3\u6362\u539f\u5219\uff0c\u4f46\u4e0d\u59a8\u788d\u5927\u5bb6\u5e94\u7528\u8fd9\u6837\u7684\u601d\u7ef4\u53bb\u8fdb\u884c\u5f00\u53d1\uff0c\u5e76\u5f62\u6210\u4e86\u67d0\u79cd\u56fa\u6709\u7684\u8ba4\u77e5\u2014\u2014\u51e1\u662f\u9700\u8981\u7236\u7c7b\u7684\u573a\u5408\uff0c\u6211\u90fd\u53ef\u4ee5\u4f20\u5165\u5b50\u7c7b\u3002<\/p>\n<p>\u6b63\u662f\u8fd9\u79cd\u601d\u7ef4\u5b9a\u5f0f\uff0c\u5bfc\u81f4\u6211\u4eec\u5728\u7406\u89e3\u6cdb\u578b\u53c2\u6570\u65f6\u9047\u5230\u56f0\u96be<\/p>\n<h2>\u6cdb\u578b\u53c2\u6570\u4e0d\u9002\u7528\u91cc\u6c0f\u4ee3\u6362\u539f\u5219<\/h2>\n<p>\u5982\u679c\u4f60\u8981\u4f20\u5165\u7684\u53c2\u6570\u672c\u8eab\u662f\u4e2a\u6cdb\u578b\u53c2\u6570\uff0c\u4f8b\u5982 <code>List&lt;Object&gt;<\/code>\uff0c<code>Map&lt;String, String&gt;<\/code> \u8fd9\u7c7b\uff0c\u90a3\u4e48\u76ee\u6807\u6cdb\u578b\u8981\u6c42\u4ec0\u4e48\u53c2\u6570\u7c7b\u578b\uff0c\u4f60\u5c31\u8981\u58f0\u660e\u4ec0\u4e48\u7c7b\u578b\u4f20\u7ed9\u4ed6\uff0c\u58f0\u660e\u6210\u5b50\u7c7b\u540e\u518d\u4f20\u5165\u662f\u4e0d\u884c\u7684\uff0c\u6700\u5178\u578b\u7684\u5c31\u662f\u6cdb\u578b\u53c2\u6570\u4e3a <code>Object<\/code> \u7684\u65f6\u5019<\/p>\n<p>\u770b\u4e2a\u4f8b\u5b50<\/p>\n<pre><code class=\"language-java\">public static final void print(List&lt;Object&gt; list) {\n    System.out.println(list);\n}\n\npublic void test() {\n    List&lt;Integer&gt; intList = Arrays.asList(1,2,3,4);\n    \/\/ \u7c7b\u578b List&lt;Integer&gt; \u548c\u6cdb\u578b\u53c2\u6570 List&lt;Object&gt; \u4e0d\u4e00\u81f4, \u7f16\u8bd1\u4e0d\u901a\u8fc7\n    print(intList);\n\n    List&lt;Object&gt; objList = Arrays.asList(1,2,3,4);\n    \/\/ \u7f16\u8bd1\u901a\u8fc7\n    print(objList);\n}<\/code><\/pre>\n<p>\u7531\u4e8e\u91cc\u6c0f\u4ee3\u6362\u539f\u5219\u7684\u601d\u7ef4\u5b9a\u5f0f\u5b58\u5728\uff0c\u6709\u4e9b\u540c\u5b66\u60f3\u5f53\u7136\u7684\u8ba4\u4e3a <code>List&lt;Integer&gt;<\/code> \u4e5f\u662f <code>List&lt;Object&gt;<\/code>\uff0c\u5b9e\u9645\u4e0a\u8fd9\u79cd\u573a\u666f\u4e0d\u9002\u5408\u91cc\u6c0f\u4ee3\u6362\u539f\u5219\uff0c\u6cdb\u578b\u8981\u7684\u662f <code>List&lt;Object&gt;<\/code>\uff0c\u5c31\u53ea\u80fd\u4f20 <code>List&lt;Object&gt;<\/code><\/p>\n<h2>\u6cdb\u578b\u53c2\u6570 ? \u4e0d\u8868\u793a\u4efb\u4f55\u7c7b\u578b<\/h2>\n<p>\u5728\u4f7f\u7528 <code>?<\/code> \u4f5c\u4e3a\u6cdb\u578b\u53c2\u6570\u65f6\uff0c\u53ef\u4ee5\u7406\u89e3\u4e3a <code>?<\/code> \u662f\u4e2a\u901a\u914d\u7b26\uff0c\u4efb\u4f55\u7c7b\u578b\u90fd ok\uff0c\u4f46\u672c\u8eab\u4e0d\u8868\u793a\u7279\u5b9a\u7c7b\u578b\uff0c\u8fd9\u662f\u5b83\u548c <code>Object<\/code> \u7684\u6700\u5927\u533a\u522b\uff0c\u5982\u679c\u7528\u91cc\u6c0f\u4ee3\u6362\u539f\u5219\u6765\u5957\u8fd9\u79cd\u573a\u666f\uff0c\u4f1a\u89c9\u5f97 <code>?<\/code> \u66f4\u50cf\u662f\u6240\u6709\u7c7b\u7684\u7236\u7c7b\uff0c\u90a3\u4e0d\u5c31\u8868\u793a <code>Object<\/code> \u7c7b\u4e86\u5417\uff1f\u4e0d\u80fd\u8fd9\u6837\u60f3\uff0c\u4f7f\u7528\u6cdb\u578b\u65f6\uff0c\u629b\u5f00\u91cc\u6c0f\u4ee3\u6362\u7684\u601d\u7ef4\u5b9a\u5f0f\u3002<\/p>\n<p>\u770b\u4e2a\u4f8b\u5b50<\/p>\n<pre><code class=\"language-java\">public static final void print(List&lt;?&gt; list) {\n    System.out.println(list);\n}\n\npublic void test() {\n    List&lt;Integer&gt; intList = Arrays.asList(1,2,3,4);\n    \/\/ \u7f16\u8bd1\u901a\u8fc7\n    print(intList);\n\n    List&lt;Object&gt; objList = Arrays.asList(1,2,3,4);\n    \/\/ \u7f16\u8bd1\u901a\u8fc7\n    print(objList);\n\n    List&lt;String&gt; strList = Arrays.asList(&quot;tom&quot;,&quot;jerry&quot;,&quot;mike&quot;);\n    \/\/ \u7f16\u8bd1\u901a\u8fc7\n    print(strList);\n}<\/code><\/pre>\n<p>\u53ef\u4ee5\u53d1\u73b0\uff0c<code>?<\/code> \u662f\u6765\u8005\u4e0d\u62d2\u7684<\/p>\n<h2>? \u53c2\u6570\u8fdb\u9636<\/h2>\n<p>\u5bf9\u4e8e\u58f0\u660e\u4e3a <code>?<\/code> \u7684\u6cdb\u578b\uff0c\u8981\u6ce8\u610f\uff1a\u4f60\u6ca1\u6709\u529e\u6cd5\u5b9a\u4e49\u4e00\u4e2a\u7c7b\u578b\u4e3a <code>?<\/code> \u7684\u5bf9\u8c61\uff0c\u4ece\u800c\u5bfc\u81f4\u4f60\u65e0\u6cd5\u8c03\u7528\u90a3\u4e9b\u9700\u8981\u4f20\u5165\u6cdb\u578b\u53c2\u6570\u7684\u65b9\u6cd5\uff0c\u6bd4\u5982 <code>List<\/code> \u7684 <code>add(E e)<\/code>\uff0c<code>Map<\/code> \u7684 <code>put(K key, V value)<\/code> \u8fd9\u7c7b\u7684\u65b9\u6cd5<\/p>\n<pre><code class=\"language-java\">public void test() {\n    List&lt;Integer&gt; list = new ArrayList&lt;&gt;();\n    list.add(1);\n    list.add(2);\n    list.add(3);\n\n    List&lt;?&gt; intList = list;\n    \/\/ \u7f16\u8bd1\u4e0d\u901a\u8fc7\uff0c\u53c2\u6570 4 \u7684 \u7c7b\u578b\u4e0d\u662f ?\n    intList.add(4);\n    \/\/ \u53c2\u6570 0 \u4e0d\u9700\u8981\u6cdb\u578b\u5316\uff0c\u8be5\u65b9\u6cd5\u6b63\u5e38\u6267\u884c\n    intList.remove(0);\n}<\/code><\/pre>\n<h2>\u7ed3\u8bed<\/h2>\n<p>\u5176\u5b9e\u4e5f\u5f88\u7b80\u5355\uff0c\u6211\u4eec\u5728\u9762\u5bf9\u6cdb\u578b\u65f6\uff0c\u4ece\u91cc\u6c0f\u4ee3\u6362\u7684\u601d\u7ef4\u5b9a\u5f0f\u91cc\u8131\u8eab\u51fa\u6765\uff0c\u6cdb\u578b\u91cc\u7684\u4e00\u4e9b\u96be\u4ee5\u7406\u89e3\u4e4b\u5904\u5c31\u5f88\u7b80\u5355\u4e86<\/p>\n<p>\u65e0\u8d23\u4efb\u8054\u60f3\u4e00\u4e0b\uff0c\u4e5f\u8bb8\u4e00\u4e2a\u521a\u63a5\u89e6 Java \u8bed\u8a00\u7684\u5c0f\u767d\uff0c\u66f4\u5bb9\u6613\u638c\u63e1\u6cdb\u578b\u5462<\/p>\n","protected":false},"excerpt":{"rendered":"<p>\u6982\u8ff0 \u9762\u5411\u5bf9\u8c61\u7684\u8bbe\u8ba1\u6709\u4e2a\u57fa\u672c\u539f\u5219\uff1a\u91cc\u6c0f\u4ee3\u6362\u539f\u5219\uff0c\u7b80\u5355\u7406\u89e3\u4e3a\u51e1\u662f\u63a5\u53d7\u7236\u7c7b\u7684\u573a\u5408\uff0c\u90fd\u53ef\u4ee5\u63a5\u53d7\u5176\u5b50\u7c7b\u3002 Java \u662f [&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":[10],"class_list":["post-128","post","type-post","status-publish","format-standard","hentry","category-java","tag-10"],"yoast_head":"<!-- This site is optimized with the Yoast SEO plugin v22.3 - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>Java \u6cdb\u578b\u53c2\u6570\u4e2d\u901a\u914d\u7b26 ? \u548c Object \u7684\u5dee\u5f02 - \u62d2\u6d77\u7a7a\u95f4<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/refusea.com\/?p=128\" \/>\n<meta name=\"twitter:label1\" content=\"\u4f5c\u8005\" \/>\n\t<meta name=\"twitter:data1\" content=\"refusea.com\" \/>\n\t<meta name=\"twitter:label2\" content=\"\u9884\u8ba1\u9605\u8bfb\u65f6\u95f4\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 \u5206\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"TechArticle\",\"@id\":\"https:\/\/refusea.com\/?p=128#article\",\"isPartOf\":{\"@id\":\"https:\/\/refusea.com\/?p=128\"},\"author\":{\"name\":\"refusea.com\",\"@id\":\"https:\/\/refusea.com\/#\/schema\/person\/b5393cc8b15717000d19424552aae0df\"},\"headline\":\"Java \u6cdb\u578b\u53c2\u6570\u4e2d\u901a\u914d\u7b26 ? \u548c Object \u7684\u5dee\u5f02\",\"datePublished\":\"2020-11-23T09:01:58+00:00\",\"dateModified\":\"2020-12-20T12:36:33+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/refusea.com\/?p=128\"},\"wordCount\":5,\"commentCount\":0,\"publisher\":{\"@id\":\"https:\/\/refusea.com\/#\/schema\/person\/b5393cc8b15717000d19424552aae0df\"},\"keywords\":[\"\u6cdb\u578b\"],\"articleSection\":[\"Java\"],\"inLanguage\":\"zh-Hans\",\"potentialAction\":[{\"@type\":\"CommentAction\",\"name\":\"Comment\",\"target\":[\"https:\/\/refusea.com\/?p=128#respond\"]}]},{\"@type\":[\"WebPage\",\"ProfilePage\"],\"@id\":\"https:\/\/refusea.com\/?p=128\",\"url\":\"https:\/\/refusea.com\/?p=128\",\"name\":\"Java \u6cdb\u578b\u53c2\u6570\u4e2d\u901a\u914d\u7b26 ? \u548c Object \u7684\u5dee\u5f02 - \u62d2\u6d77\u7a7a\u95f4\",\"isPartOf\":{\"@id\":\"https:\/\/refusea.com\/#website\"},\"datePublished\":\"2020-11-23T09:01:58+00:00\",\"dateModified\":\"2020-12-20T12:36:33+00:00\",\"breadcrumb\":{\"@id\":\"https:\/\/refusea.com\/?p=128#breadcrumb\"},\"inLanguage\":\"zh-Hans\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/refusea.com\/?p=128\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/refusea.com\/?p=128#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"\u9996\u9875\",\"item\":\"https:\/\/refusea.com\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"Java \u6cdb\u578b\u53c2\u6570\u4e2d\u901a\u914d\u7b26 ? \u548c Object \u7684\u5dee\u5f02\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/refusea.com\/#website\",\"url\":\"https:\/\/refusea.com\/\",\"name\":\"\u62d2\u6d77\u7a7a\u95f4\",\"description\":\"\u62d2\u6d77\u7684\u4e2a\u4eba\u535a\u5ba2\",\"publisher\":{\"@id\":\"https:\/\/refusea.com\/#\/schema\/person\/b5393cc8b15717000d19424552aae0df\"},\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\/\/refusea.com\/?s={search_term_string}\"},\"query-input\":\"required name=search_term_string\"}],\"inLanguage\":\"zh-Hans\"},{\"@type\":[\"Person\",\"Organization\"],\"@id\":\"https:\/\/refusea.com\/#\/schema\/person\/b5393cc8b15717000d19424552aae0df\",\"name\":\"refusea.com\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"zh-Hans\",\"@id\":\"https:\/\/refusea.com\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/7f7489b4afdbd952db64e7a6704d1258?s=96&d=mm&r=g\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/7f7489b4afdbd952db64e7a6704d1258?s=96&d=mm&r=g\",\"caption\":\"refusea.com\"},\"logo\":{\"@id\":\"https:\/\/refusea.com\/#\/schema\/person\/image\/\"},\"mainEntityOfPage\":{\"@id\":\"https:\/\/refusea.com\/?p=128\"},\"sameAs\":[\"https:\/\/refusea.com\"]}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"Java \u6cdb\u578b\u53c2\u6570\u4e2d\u901a\u914d\u7b26 ? \u548c Object \u7684\u5dee\u5f02 - \u62d2\u6d77\u7a7a\u95f4","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/refusea.com\/?p=128","twitter_misc":{"\u4f5c\u8005":"refusea.com","\u9884\u8ba1\u9605\u8bfb\u65f6\u95f4":"1 \u5206"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"TechArticle","@id":"https:\/\/refusea.com\/?p=128#article","isPartOf":{"@id":"https:\/\/refusea.com\/?p=128"},"author":{"name":"refusea.com","@id":"https:\/\/refusea.com\/#\/schema\/person\/b5393cc8b15717000d19424552aae0df"},"headline":"Java \u6cdb\u578b\u53c2\u6570\u4e2d\u901a\u914d\u7b26 ? \u548c Object \u7684\u5dee\u5f02","datePublished":"2020-11-23T09:01:58+00:00","dateModified":"2020-12-20T12:36:33+00:00","mainEntityOfPage":{"@id":"https:\/\/refusea.com\/?p=128"},"wordCount":5,"commentCount":0,"publisher":{"@id":"https:\/\/refusea.com\/#\/schema\/person\/b5393cc8b15717000d19424552aae0df"},"keywords":["\u6cdb\u578b"],"articleSection":["Java"],"inLanguage":"zh-Hans","potentialAction":[{"@type":"CommentAction","name":"Comment","target":["https:\/\/refusea.com\/?p=128#respond"]}]},{"@type":["WebPage","ProfilePage"],"@id":"https:\/\/refusea.com\/?p=128","url":"https:\/\/refusea.com\/?p=128","name":"Java \u6cdb\u578b\u53c2\u6570\u4e2d\u901a\u914d\u7b26 ? \u548c Object \u7684\u5dee\u5f02 - \u62d2\u6d77\u7a7a\u95f4","isPartOf":{"@id":"https:\/\/refusea.com\/#website"},"datePublished":"2020-11-23T09:01:58+00:00","dateModified":"2020-12-20T12:36:33+00:00","breadcrumb":{"@id":"https:\/\/refusea.com\/?p=128#breadcrumb"},"inLanguage":"zh-Hans","potentialAction":[{"@type":"ReadAction","target":["https:\/\/refusea.com\/?p=128"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/refusea.com\/?p=128#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"\u9996\u9875","item":"https:\/\/refusea.com\/"},{"@type":"ListItem","position":2,"name":"Java \u6cdb\u578b\u53c2\u6570\u4e2d\u901a\u914d\u7b26 ? \u548c Object \u7684\u5dee\u5f02"}]},{"@type":"WebSite","@id":"https:\/\/refusea.com\/#website","url":"https:\/\/refusea.com\/","name":"\u62d2\u6d77\u7a7a\u95f4","description":"\u62d2\u6d77\u7684\u4e2a\u4eba\u535a\u5ba2","publisher":{"@id":"https:\/\/refusea.com\/#\/schema\/person\/b5393cc8b15717000d19424552aae0df"},"potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/refusea.com\/?s={search_term_string}"},"query-input":"required name=search_term_string"}],"inLanguage":"zh-Hans"},{"@type":["Person","Organization"],"@id":"https:\/\/refusea.com\/#\/schema\/person\/b5393cc8b15717000d19424552aae0df","name":"refusea.com","image":{"@type":"ImageObject","inLanguage":"zh-Hans","@id":"https:\/\/refusea.com\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/7f7489b4afdbd952db64e7a6704d1258?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/7f7489b4afdbd952db64e7a6704d1258?s=96&d=mm&r=g","caption":"refusea.com"},"logo":{"@id":"https:\/\/refusea.com\/#\/schema\/person\/image\/"},"mainEntityOfPage":{"@id":"https:\/\/refusea.com\/?p=128"},"sameAs":["https:\/\/refusea.com"]}]}},"_links":{"self":[{"href":"https:\/\/refusea.com\/index.php?rest_route=\/wp\/v2\/posts\/128"}],"collection":[{"href":"https:\/\/refusea.com\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/refusea.com\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/refusea.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/refusea.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=128"}],"version-history":[{"count":4,"href":"https:\/\/refusea.com\/index.php?rest_route=\/wp\/v2\/posts\/128\/revisions"}],"predecessor-version":[{"id":146,"href":"https:\/\/refusea.com\/index.php?rest_route=\/wp\/v2\/posts\/128\/revisions\/146"}],"wp:attachment":[{"href":"https:\/\/refusea.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=128"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/refusea.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=128"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/refusea.com\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=128"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}