AppletTalk.com Java discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  static member question          AppletTalk.com Forum Index -> Java Help View previous topic :: View next topic   Author Message cdx Guest Posted: Thu May 26, 2005 12:55 am    Post subject: static member question I'm not sure if java has this capability, but can someone let me know? Suppose I have Class A, with subclasses A1 and A2 I want a static variable with the same name for each of the subclasses. For instance, I would like to have this heirarchy have a static var called "factory" such that each subclass will have it's own single instance of it. I know that I can define this static var at each of the subclass levels (Class A1 and A2), but is there a way to define it in Class A such that A1 and A2 will have their own? I thought I remember a special type like this in C#, but could not find anything like this in java. Thanks cdx Back to top Sebastian Scheid Guest Posted: Thu May 26, 2005 11:38 am    Post subject: Re: static member question "cdx" <jm1 (AT) dicehome (DOT) com> schrieb im Newsbeitrag news:ccKdnTpPhPmKgwjfRVn-pQ (AT) comcast (DOT) com... Quote: I'm not sure if java has this capability, but can someone let me know? Suppose I have Class A, with subclasses A1 and A2 I want a static variable with the same name for each of the subclasses. For instance, I would like to have this heirarchy have a static var called "factory" such that each subclass will have it's own single instance of it. I know that I can define this static var at each of the subclass levels (Class A1 and A2), but is there a way to define it in Class A such that A1 and A2 will have their own? I thought I remember a special type like this in C#, but could not find anything like this in java. No, you cannot do that. You have to declare a static variable in each of the classes if you want each of them to have its own. In Java you cannot have a baseclass with static elements (like a static factory method or a static getInstance() method of a singleton) which is extended by a concrete subclass (e.g. a concrete Singleton) which then has these static elements of the baseclass for its own. If you just want to implement the abstract factory design pattern, only your abstract baseclass (A) needs the factory field (an instance of the concrete subclass A1 or A2). Your clients will always use A.getFactory() to get the right implementation and do not know anything about A1 or A2. Regards Sebastian Back to top Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First         AppletTalk.com Forum Index -> Java Help All times are GMT Page 1 of 1   Jump to: Select a forum Java Newsgroups----------------Java DiscussionsWeb-based java games comp.lang.java 3D Graphics API's for Java Java: Support and criticism Java System Announcements comp.lang.java.api JavaBeans Java and CORBA Java and Databases comp.lang.java.developer Java GUI Toolkits Java Help comp.lang.java.javascript JVM, native methods and hardware comp.lang.java.misc Java Language Programming Security and Java comp.lang.java.setup Java Software Tools comp.lang.java.tech ibm.software.java.linux  Non-English Java Newsgroups----------------Java Language (German)Language Java (Français)Java (Italian)  You cannot post new topics in this forum You cannot reply to topics in this forum You cannot edit your posts in this forum You cannot delete your posts in this forum You cannot vote in polls in this forum Powered by phpBB © 2001, 2006 phpBB Group SEO toolkit © 2004-2006 webmedic.