AppletTalk.com Java discussions newsgroups   Archives   FAQ   Search   Memberlist   Usergroups   Register   Profile   Log in to check your private messages   Log in  Inheritance question???Object class          AppletTalk.com Forum Index -> Java Help View previous topic :: View next topic   Author Message vaibhav Guest Posted: Sun May 13, 2007 1:34 am    Post subject: Inheritance question???Object class hi all, im basically a newbie to java java doesnt support multiple inheritance ie you can atmost extend only from one class and implement other interfaces to simulate mulitple inheritance as far as i have read by default every class extends the Object class <- ie class abc == class abc extends Object now since every class has already extended from it how can it extend from other classes from my point of view if java has only single inheritance this should not be possible and since it is possible there should be a way out if not then how is this achieved??? regards vaibhav.y.netkar Back to top Eric Sosman Guest Posted: Sun May 13, 2007 2:06 am    Post subject: Re: Inheritance question???Object class vaibhav wrote: Quote: hi all, im basically a newbie to java java doesnt support multiple inheritance ie you can atmost extend only from one class and implement other interfaces to simulate mulitple inheritance as far as i have read by default every class extends the Object class - ie class abc == class abc extends Object now since every class has already extended from it how can it extend from other classes from my point of view if java has only single inheritance this should not be possible class ABC extends Object class DEF extends ABC class GHI extends DEF class JKL extends GHI ... Quote: and since it is possible there should be a way out if not then how is this achieved??? You have only one mother, and she has only one mother, and she in turn has only one mother; that's single inheritance. Even though you are directly descended from only one of them, you are "transitively descended" from them all. To put it less fancifully: Consider drawing a graph of all Java classes in a JVM, with arrows from each class to the class it extends. From any class, there is an oriented path leading (eventually) to Object. Single inheritance means that the path is unique, that the graph is a tree with Object as its root. -- Eric Sosman esosman@acm-dot-org.invalid Back to top Richard Reynolds Guest Posted: Sun May 13, 2007 2:07 am    Post subject: Re: Inheritance question???Object class "vaibhav" <vaibhav.netkar (AT) gmail (DOT) com> wrote in message news:1179002056.961054.54030 (AT) e51g2000hsg (DOT) googlegroups.com... Quote: hi all, im basically a newbie to java java doesnt support multiple inheritance ie you can atmost extend only from one class and implement other interfaces to simulate mulitple inheritance as far as i have read by default every class extends the Object class - ie class abc == class abc extends Object now since every class has already extended from it how can it extend from other classes from my point of view if java has only single inheritance this should not be possible and since it is possible there should be a way out if not then how is this achieved??? regards vaibhav.y.netkar but that isn't multiple inheritance, since every class implicitly extends Object, Object is the "root" of your single inheritance tree e.g. you write a class with no "extends" clause: Object->YourClass you now write a class that extends YourClass: Object->YourClass->YourNewClass that's still single inheritance. Back to top Lew Guest Posted: Sun May 13, 2007 9:40 pm    Post subject: Re: Inheritance question???Object class "vaibhav" <vaibhav.netkar (AT) gmail (DOT) com> wrote Quote: as far as i have read by default every class extends the Object class The key words are "by default". That does not mean "always". It completely negates the "every". It is only by default that a class extends Object. It certainly does not have to. The actual rule is, "Every class extends exactly one other class, except Object, which extends no other class." The English first-person singular pronoun "I" is always capitalized (or capitalised, depending on which dialect of English you write). -- Lew 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.