Re: Inheritance question???Object class

From:

Eric Sosman <esosman@acm-dot-org.invalid>

Newsgroups:

comp.lang.java.help

Date:

Sat, 12 May 2007 17:06:31 -0400

Message-ID:

<pdKdnfGoJZIxsdvbnZ2dnUVZ_qupnZ2d@comcast.com>

vaibhav wrote:

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
     ...

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