{"id":17625,"date":"2024-03-15T15:24:08","date_gmt":"2024-03-15T15:24:08","guid":{"rendered":"https:\/\/www.silicloud.com\/blog\/what-is-the-implementation-method-of-the-java-singleton-pattern-2\/"},"modified":"2024-03-21T11:21:08","modified_gmt":"2024-03-21T11:21:08","slug":"what-is-the-implementation-method-of-the-java-singleton-pattern-2","status":"publish","type":"post","link":"https:\/\/www.silicloud.com\/blog\/what-is-the-implementation-method-of-the-java-singleton-pattern-2\/","title":{"rendered":"What is the implementation method of the Java singleton pattern?"},"content":{"rendered":"<p>There are several ways to implement the singleton pattern in Java.<\/p>\n<ol>\n<li>Eager initialization: a singleton object is created when the class is loaded, and it is returned through a static method. This approach is safe in a multi-threaded environment.<\/li>\n<\/ol>\n<pre class=\"post-pre\"><code><span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title class_\">Singleton<\/span> {\r\n    <span class=\"hljs-keyword\">private<\/span> <span class=\"hljs-keyword\">static<\/span> <span class=\"hljs-keyword\">final<\/span> <span class=\"hljs-type\">Singleton<\/span> <span class=\"hljs-variable\">instance<\/span> <span class=\"hljs-operator\">=<\/span> <span class=\"hljs-keyword\">new<\/span> <span class=\"hljs-title class_\">Singleton<\/span>();\r\n    \r\n    <span class=\"hljs-keyword\">private<\/span> <span class=\"hljs-title function_\">Singleton<\/span><span class=\"hljs-params\">()<\/span> {}\r\n    \r\n    <span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">static<\/span> Singleton <span class=\"hljs-title function_\">getInstance<\/span><span class=\"hljs-params\">()<\/span> {\r\n        <span class=\"hljs-keyword\">return<\/span> instance;\r\n    }\r\n}\r\n<\/code><\/pre>\n<ol>\n<li>Lazy Initialization: The singleton object is created only when the method to obtain it is called. This method requires thread synchronization in a multi-threaded environment.<\/li>\n<\/ol>\n<pre class=\"post-pre\"><code><span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title class_\">Singleton<\/span> {\r\n    <span class=\"hljs-keyword\">private<\/span> <span class=\"hljs-keyword\">static<\/span> Singleton instance;\r\n\r\n    <span class=\"hljs-keyword\">private<\/span> <span class=\"hljs-title function_\">Singleton<\/span><span class=\"hljs-params\">()<\/span> {}\r\n\r\n    <span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">static<\/span> <span class=\"hljs-keyword\">synchronized<\/span> Singleton <span class=\"hljs-title function_\">getInstance<\/span><span class=\"hljs-params\">()<\/span> {\r\n        <span class=\"hljs-keyword\">if<\/span> (instance == <span class=\"hljs-literal\">null<\/span>) {\r\n            instance = <span class=\"hljs-keyword\">new<\/span> <span class=\"hljs-title class_\">Singleton<\/span>();\r\n        }\r\n        <span class=\"hljs-keyword\">return<\/span> instance;\r\n    }\r\n}\r\n<\/code><\/pre>\n<ol>\n<li>Double-Checked Locking: An improvement on the lazy initialization method, adding an extra null check when creating an instance to reduce unnecessary synchronization overhead.<\/li>\n<\/ol>\n<pre class=\"post-pre\"><code><span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title class_\">Singleton<\/span> {\r\n    <span class=\"hljs-keyword\">private<\/span> <span class=\"hljs-keyword\">volatile<\/span> <span class=\"hljs-keyword\">static<\/span> Singleton instance;\r\n\r\n    <span class=\"hljs-keyword\">private<\/span> <span class=\"hljs-title function_\">Singleton<\/span><span class=\"hljs-params\">()<\/span> {}\r\n\r\n    <span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">static<\/span> Singleton <span class=\"hljs-title function_\">getInstance<\/span><span class=\"hljs-params\">()<\/span> {\r\n        <span class=\"hljs-keyword\">if<\/span> (instance == <span class=\"hljs-literal\">null<\/span>) {\r\n            <span class=\"hljs-keyword\">synchronized<\/span> (Singleton.class) {\r\n                <span class=\"hljs-keyword\">if<\/span> (instance == <span class=\"hljs-literal\">null<\/span>) {\r\n                    instance = <span class=\"hljs-keyword\">new<\/span> <span class=\"hljs-title class_\">Singleton<\/span>();\r\n                }\r\n            }\r\n        }\r\n        <span class=\"hljs-keyword\">return<\/span> instance;\r\n    }\r\n}\r\n<\/code><\/pre>\n<ol>\n<li>Static Inner Class: Utilize the characteristics of a static inner class to achieve lazy loading and ensure thread safety.<\/li>\n<\/ol>\n<pre class=\"post-pre\"><code><span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title class_\">Singleton<\/span> {\r\n    <span class=\"hljs-keyword\">private<\/span> <span class=\"hljs-title function_\">Singleton<\/span><span class=\"hljs-params\">()<\/span> {}\r\n\r\n    <span class=\"hljs-keyword\">private<\/span> <span class=\"hljs-keyword\">static<\/span> <span class=\"hljs-keyword\">class<\/span> <span class=\"hljs-title class_\">SingletonHolder<\/span> {\r\n        <span class=\"hljs-keyword\">private<\/span> <span class=\"hljs-keyword\">static<\/span> <span class=\"hljs-keyword\">final<\/span> <span class=\"hljs-type\">Singleton<\/span> <span class=\"hljs-variable\">instance<\/span> <span class=\"hljs-operator\">=<\/span> <span class=\"hljs-keyword\">new<\/span> <span class=\"hljs-title class_\">Singleton<\/span>();\r\n    }\r\n\r\n    <span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">static<\/span> Singleton <span class=\"hljs-title function_\">getInstance<\/span><span class=\"hljs-params\">()<\/span> {\r\n        <span class=\"hljs-keyword\">return<\/span> SingletonHolder.instance;\r\n    }\r\n}\r\n<\/code><\/pre>\n<ol>\n<li>Enumeration (Enum): Using the properties of enumeration to implement the singleton pattern. Enumerations are thread-safe and will only be instantiated once.<\/li>\n<\/ol>\n<pre class=\"post-pre\"><code><span class=\"hljs-keyword\">public<\/span> <span class=\"hljs-keyword\">enum<\/span> <span class=\"hljs-title class_\">Singleton<\/span> {\r\n    INSTANCE;\r\n\r\n    <span class=\"hljs-comment\">\/\/ \u9700\u8981\u6dfb\u52a0\u7684\u5355\u4f8b\u5bf9\u8c61\u7684\u5176\u4ed6\u65b9\u6cd5<\/span>\r\n}\r\n<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>There are several ways to implement the singleton pattern in Java. Eager initialization: a singleton object is created when the class is loaded, and it is returned through a static method. This approach is safe in a multi-threaded environment. public class Singleton { private static final Singleton instance = new Singleton(); private Singleton() {} public [&hellip;]<\/p>\n","protected":false},"author":7,"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-17625","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>What is the implementation method of the Java singleton pattern? - 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\/what-is-the-implementation-method-of-the-java-singleton-pattern-2\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"What is the implementation method of the Java singleton pattern?\" \/>\n<meta property=\"og:description\" content=\"There are several ways to implement the singleton pattern in Java. Eager initialization: a singleton object is created when the class is loaded, and it is returned through a static method. This approach is safe in a multi-threaded environment. public class Singleton { private static final Singleton instance = new Singleton(); private Singleton() {} public [&hellip;]\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.silicloud.com\/blog\/what-is-the-implementation-method-of-the-java-singleton-pattern-2\/\" \/>\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=\"2024-03-15T15:24:08+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2024-03-21T11:21:08+00:00\" \/>\n<meta name=\"author\" content=\"Sophia Anderson\" \/>\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=\"Sophia Anderson\" \/>\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\/what-is-the-implementation-method-of-the-java-singleton-pattern-2\/#article\",\"isPartOf\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/what-is-the-implementation-method-of-the-java-singleton-pattern-2\/\"},\"author\":{\"name\":\"Sophia Anderson\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/#\/schema\/person\/19a24313de9c988db3d69226b4a40a30\"},\"headline\":\"What is the implementation method of the Java singleton pattern?\",\"datePublished\":\"2024-03-15T15:24:08+00:00\",\"dateModified\":\"2024-03-21T11:21:08+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/what-is-the-implementation-method-of-the-java-singleton-pattern-2\/\"},\"wordCount\":137,\"commentCount\":0,\"publisher\":{\"@id\":\"https:\/\/www.silicloud.com\/blog\/#organization\"},\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\/\/www.silicloud.com\/blog\/what-is-the-implementation-method-of-the-java-singleton-pattern-2\/\",\"url\":\"https:\/\/www.silicloud.com\/blog\/what-is-the-implementation-method-of-the-java-singleton-pattern-2\/\",\"name\":\"What is the implementation method of the Java singleton pattern? 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