{"id":22015,"date":"2024-03-15T22:55:15","date_gmt":"2024-03-15T22:55:15","guid":{"rendered":"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/"},"modified":"2024-03-21T21:51:55","modified_gmt":"2024-03-21T21:51:55","slug":"how-to-get-the-generic-type-of-a-list-in-java","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/","title":{"rendered":"How to get the generic type of a list in Java?"},"content":{"rendered":"<p>In Java, it is not possible to directly obtain the generic type of a List because generics are erased during compilation, making it impossible to access the specific generic type information at runtime.<\/p>\n<p>However, it is possible to obtain information about the List generic type using some indirect methods. One common approach is to retrieve it through reflection.<\/p>\n<p>Here is an example code that demonstrates how to use reflection to get the generic type of a List.<\/p>\n<pre class=\"post-pre\"><code><span class=\"hljs-keyword\">import<\/span> java.lang.reflect.ParameterizedType;\r\n<span class=\"hljs-keyword\">import<\/span> java.lang.reflect.Type;\r\n<span class=\"hljs-keyword\">import<\/span> java.util.ArrayList;\r\n<span class=\"hljs-keyword\">import<\/span> java.util.List;\r\n\r\n<span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title class_\">Main<\/span> {\r\n    <span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">static<\/span> <span class=\"hljs-keyword\">void<\/span> <span class=\"hljs-title function_\">main<\/span><span class=\"hljs-params\">(String[] args)<\/span> {\r\n        List&lt;String&gt; list = <span class=\"hljs-keyword\">new<\/span> <span class=\"hljs-title class_\">ArrayList<\/span>&lt;&gt;();\r\n        <span class=\"hljs-type\">Type<\/span> <span class=\"hljs-variable\">genericType<\/span> <span class=\"hljs-operator\">=<\/span> list.getClass().getGenericSuperclass();\r\n\r\n        <span class=\"hljs-keyword\">if<\/span> (genericType <span class=\"hljs-keyword\">instanceof<\/span> ParameterizedType) {\r\n            Type[] actualTypeArguments = ((ParameterizedType) genericType).getActualTypeArguments();\r\n\r\n            <span class=\"hljs-keyword\">if<\/span> (actualTypeArguments.length &gt; <span class=\"hljs-number\">0<\/span>) {\r\n                Class&lt;?&gt; genericClass = (Class&lt;?&gt;) actualTypeArguments[<span class=\"hljs-number\">0<\/span>];\r\n                System.out.println(<span class=\"hljs-string\">\"List\u6cdb\u578b\u7c7b\u578b\u4e3a: \"<\/span> + genericClass.getName());\r\n            }\r\n        }\r\n    }\r\n}\r\n<\/code><\/pre>\n<p>In the code above, first we obtain the Class object of List, then we retrieve the generic type information of its superclass. If the generic type is of type ParameterizedType, which means it has actual type parameters, we can use the getActualTypeArguments() method to retrieve an array of actual type parameters. The first element in the array represents the generic type of the List.<\/p>\n<p>It is important to note that the above code assumes that List directly inherits from ArrayList. If List directly implements an interface or inherits from another class, the getGenericSuperclass() method may need to be adjusted. Additionally, if List does not specify a generic type, the length of the array returned by the getActualTypeArguments() method will be 0.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>In Java, it is not possible to directly obtain the generic type of a List because generics are erased during compilation, making it impossible to access the specific generic type information at runtime. However, it is possible to obtain information about the List generic type using some indirect methods. One common approach is to retrieve [&hellip;]<\/p>\n","protected":false},"author":6,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"_import_markdown_pro_load_document_selector":0,"_import_markdown_pro_submit_text_textarea":"","footnotes":""},"categories":[1],"tags":[],"class_list":["post-22015","post","type-post","status-publish","format-standard","hentry","category-uncategorized"],"yoast_head":"<!-- This site is optimized with the Yoast SEO Premium plugin v21.5 (Yoast SEO v21.5) - https:\/\/yoast.com\/wordpress\/plugins\/seo\/ -->\n<title>How to get the generic type of a list in Java? - Blog - Silicon Cloud<\/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:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"How to get the generic type of a list in Java?\" \/>\n<meta property=\"og:description\" content=\"In Java, it is not possible to directly obtain the generic type of a List because generics are erased during compilation, making it impossible to access the specific generic type information at runtime. However, it is possible to obtain information about the List generic type using some indirect methods. One common approach is to retrieve [&hellip;]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/\" \/>\n<meta property=\"og:site_name\" content=\"Blog - Silicon Cloud\" \/>\n<meta property=\"article:publisher\" content=\"https:\/\/www.facebook.com\/SiliCloudGlobal\/\" \/>\n<meta property=\"article:published_time\" content=\"2024-03-15T22:55:15+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2024-03-21T21:51:55+00:00\" \/>\n<meta name=\"author\" content=\"Benjamin Taylor\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:creator\" content=\"@SiliCloudGlobal\" \/>\n<meta name=\"twitter:site\" content=\"@SiliCloudGlobal\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Benjamin Taylor\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"1 minute\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\/\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/\"},\"author\":{\"name\":\"Benjamin Taylor\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/#\/schema\/person\/ac801fe9549a25960ce48aa2e0a691c9\"},\"headline\":\"How to get the generic type of a list in Java?\",\"datePublished\":\"2024-03-15T22:55:15+00:00\",\"dateModified\":\"2024-03-21T21:51:55+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/\"},\"wordCount\":208,\"commentCount\":0,\"publisher\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/#organization\"},\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/\",\"url\":\"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/\",\"name\":\"How to get the generic type of a list in Java? - Blog - Silicon Cloud\",\"isPartOf\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/#website\"},\"datePublished\":\"2024-03-15T22:55:15+00:00\",\"dateModified\":\"2024-03-21T21:51:55+00:00\",\"breadcrumb\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/\"]}]},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\/\/www.silicloud.com\/blog\/\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"How to get the generic type of a list in Java?\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/#website\",\"url\":\"https:\/\/www.silicloud.com\/blog\/\",\"name\":\"Silicon Cloud Blog\",\"description\":\"\",\"publisher\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/#organization\"},\"inLanguage\":\"en-US\"},{\"@type\":\"Organization\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/#organization\",\"name\":\"Silicon Cloud Blog\",\"url\":\"https:\/\/www.silicloud.com\/blog\/\",\"logo\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/#\/schema\/logo\/image\/\",\"url\":\"https:\/\/www.silicloud.com\/blog\/wp-content\/uploads\/2023\/11\/EN-SILICON-Full.png\",\"contentUrl\":\"https:\/\/www.silicloud.com\/blog\/wp-content\/uploads\/2023\/11\/EN-SILICON-Full.png\",\"width\":1024,\"height\":1024,\"caption\":\"Silicon Cloud Blog\"},\"image\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/#\/schema\/logo\/image\/\"},\"sameAs\":[\"https:\/\/www.facebook.com\/SiliCloudGlobal\/\",\"https:\/\/twitter.com\/SiliCloudGlobal\"]},{\"@type\":\"Person\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/#\/schema\/person\/ac801fe9549a25960ce48aa2e0a691c9\",\"name\":\"Benjamin Taylor\",\"image\":{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/#\/schema\/person\/image\/\",\"url\":\"https:\/\/secure.gravatar.com\/avatar\/ec2e3d3e2d525fd148047c4520ae7c1cdccd1f4b48a1a488422b31f04f345c14?s=96&d=mm&r=g\",\"contentUrl\":\"https:\/\/secure.gravatar.com\/avatar\/ec2e3d3e2d525fd148047c4520ae7c1cdccd1f4b48a1a488422b31f04f345c14?s=96&d=mm&r=g\",\"caption\":\"Benjamin Taylor\"},\"url\":\"https:\/\/www.silicloud.com\/blog\/author\/benjamintaylor\/\"}]}<\/script>\n<!-- \/ Yoast SEO Premium plugin. -->","yoast_head_json":{"title":"How to get the generic type of a list in Java? - Blog - Silicon Cloud","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:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/","og_locale":"en_US","og_type":"article","og_title":"How to get the generic type of a list in Java?","og_description":"In Java, it is not possible to directly obtain the generic type of a List because generics are erased during compilation, making it impossible to access the specific generic type information at runtime. However, it is possible to obtain information about the List generic type using some indirect methods. One common approach is to retrieve [&hellip;]","og_url":"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/","og_site_name":"Blog - Silicon Cloud","article_publisher":"https:\/\/www.facebook.com\/SiliCloudGlobal\/","article_published_time":"2024-03-15T22:55:15+00:00","article_modified_time":"2024-03-21T21:51:55+00:00","author":"Benjamin Taylor","twitter_card":"summary_large_image","twitter_creator":"@SiliCloudGlobal","twitter_site":"@SiliCloudGlobal","twitter_misc":{"Written by":"Benjamin Taylor","Est. reading time":"1 minute"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/#article","isPartOf":{"@id":"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/"},"author":{"name":"Benjamin Taylor","@id":"https:\/\/www.silicloud.com\/blog\/#\/schema\/person\/ac801fe9549a25960ce48aa2e0a691c9"},"headline":"How to get the generic type of a list in Java?","datePublished":"2024-03-15T22:55:15+00:00","dateModified":"2024-03-21T21:51:55+00:00","mainEntityOfPage":{"@id":"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/"},"wordCount":208,"commentCount":0,"publisher":{"@id":"https:\/\/www.silicloud.com\/blog\/#organization"},"inLanguage":"en-US"},{"@type":"WebPage","@id":"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/","url":"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/","name":"How to get the generic type of a list in Java? - Blog - Silicon Cloud","isPartOf":{"@id":"https:\/\/www.silicloud.com\/blog\/#website"},"datePublished":"2024-03-15T22:55:15+00:00","dateModified":"2024-03-21T21:51:55+00:00","breadcrumb":{"@id":"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/"]}]},{"@type":"BreadcrumbList","@id":"https:\/\/www.silicloud.com\/blog\/how-to-get-the-generic-type-of-a-list-in-java\/#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.silicloud.com\/blog\/"},{"@type":"ListItem","position":2,"name":"How to get the generic type of a list in Java?"}]},{"@type":"WebSite","@id":"https:\/\/www.silicloud.com\/blog\/#website","url":"https:\/\/www.silicloud.com\/blog\/","name":"Silicon Cloud Blog","description":"","publisher":{"@id":"https:\/\/www.silicloud.com\/blog\/#organization"},"inLanguage":"en-US"},{"@type":"Organization","@id":"https:\/\/www.silicloud.com\/blog\/#organization","name":"Silicon Cloud Blog","url":"https:\/\/www.silicloud.com\/blog\/","logo":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.silicloud.com\/blog\/#\/schema\/logo\/image\/","url":"https:\/\/www.silicloud.com\/blog\/wp-content\/uploads\/2023\/11\/EN-SILICON-Full.png","contentUrl":"https:\/\/www.silicloud.com\/blog\/wp-content\/uploads\/2023\/11\/EN-SILICON-Full.png","width":1024,"height":1024,"caption":"Silicon Cloud Blog"},"image":{"@id":"https:\/\/www.silicloud.com\/blog\/#\/schema\/logo\/image\/"},"sameAs":["https:\/\/www.facebook.com\/SiliCloudGlobal\/","https:\/\/twitter.com\/SiliCloudGlobal"]},{"@type":"Person","@id":"https:\/\/www.silicloud.com\/blog\/#\/schema\/person\/ac801fe9549a25960ce48aa2e0a691c9","name":"Benjamin Taylor","image":{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.silicloud.com\/blog\/#\/schema\/person\/image\/","url":"https:\/\/secure.gravatar.com\/avatar\/ec2e3d3e2d525fd148047c4520ae7c1cdccd1f4b48a1a488422b31f04f345c14?s=96&d=mm&r=g","contentUrl":"https:\/\/secure.gravatar.com\/avatar\/ec2e3d3e2d525fd148047c4520ae7c1cdccd1f4b48a1a488422b31f04f345c14?s=96&d=mm&r=g","caption":"Benjamin Taylor"},"url":"https:\/\/www.silicloud.com\/blog\/author\/benjamintaylor\/"}]}},"_links":{"self":[{"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/posts\/22015","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/users\/6"}],"replies":[{"embeddable":true,"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/comments?post=22015"}],"version-history":[{"count":1,"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/posts\/22015\/revisions"}],"predecessor-version":[{"id":55911,"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/posts\/22015\/revisions\/55911"}],"wp:attachment":[{"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/media?parent=22015"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/categories?post=22015"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.silicloud.com\/blog\/wp-json\/wp\/v2\/tags?post=22015"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}