{"id":32932,"date":"2023-02-03T04:00:33","date_gmt":"2023-02-02T22:30:33","guid":{"rendered":"https:\/\/jassweb.com\/solved\/solved-static-class-instance-inside-class\/"},"modified":"2023-02-03T04:00:33","modified_gmt":"2023-02-02T22:30:33","slug":"solved-static-class-instance-inside-class","status":"publish","type":"post","link":"https:\/\/jassweb.com\/solved\/solved-static-class-instance-inside-class\/","title":{"rendered":"[Solved] Static class instance inside class"},"content":{"rendered":"

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What you have there is a static method getLibrary()<\/code> that returns the same instance for all callers. That’s called a Singleton<\/strong> – although there’s better ways to code them. <\/p>\n

Then again your supposed Singleton (TestLibrary) exhibits methods that when called change internal state<\/strong> – most important, the ErrorHandler<\/code>.<\/p>\n

This will cause strange behaviour, especially in multithreaded systems. <\/p>\n

Code like this:<\/p>\n

TestLibrary.getLibrary().run(\"\".split(\"\"));\nErrorHandler eh = TestLibrary.getErrorHandler();\nassertEquals(eh, TestLibrary.getErrorHandler());\n<\/code><\/pre>\n
might fail. Because someone<\/em> (meaning: some other thread) might have just happend to call init() between lines 2 and 3, causing ErrorHandler to be set to just another value. <\/p>\n
If you need<\/strong> to initialize your TestLibrary before use, you should do it once, and once only<\/em> – so you’re better of putting this into the constructor of TestLibrary.<\/p>\n
If you need TestLibraries that are intialized different<\/strong> throughout your code, you should remove the Singleton pattern and stick to plain <\/p>\n
  TestLibrary tl = new TestLibrary();\n  tl.run(\"\".split(\"\"));\n<\/code><\/pre>\n
Read more about Singleton in What is an efficient way to implement a singleton pattern in Java?<\/p>\n<\/p><\/div>\n
<\/div>\n<\/div>\n
            1<\/span> <\/p><\/div>\n<\/div>\n
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solved Static class instance inside class <\/p>\n","protected":false},"excerpt":{"rendered":"
[ad_1] What you have there is a static method getLibrary() that returns the same instance for all callers. That’s called a Singleton – although there’s better ways to code them. Then again your supposed Singleton (TestLibrary) exhibits methods that when called change internal state – most important, the ErrorHandler. This will cause strange behaviour, especially … Read more<\/a><\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[320],"tags":[323,903],"class_list":["post-32932","post","type-post","status-publish","format-standard","hentry","category-solved","tag-java","tag-static"],"yoast_head":"\n[Solved] Static class instance inside class - JassWeb<\/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:\/\/jassweb.com\/solved\/solved-static-class-instance-inside-class\/\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"[Solved] Static class instance inside class - JassWeb\" \/>\n<meta property=\"og:description\" content=\"[ad_1] What you have there is a static method getLibrary() that returns the same instance for all callers. That’s called a Singleton – although there’s better ways to code them. Then again your supposed Singleton (TestLibrary) exhibits methods that when called change internal state – most important, the ErrorHandler. This will cause strange behaviour, especially ... 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