This week's book giveaway is in the OCAJP 8 forum. We're giving away four copies of OCA Java SE 8 Programmer I Study Guide and have Edward Finegan & Robert Liguori on-line! See this thread for details.
Originally posted by SenthilNathan CAlagan: Why java doesn't support multiple inheritance? I know indirectly it can be achieved through Interface. Thanks, senthil
I'm hardly the one to answer this as I am truly a newbie but I just heard comments on this very subject while listening to Bruce Eckel's Thinking in Java CD. It's chapter 8 slide 4 in case you have it. It's not allowed because of the problem you run into while upcasting in C++. If you have an object x and object A and B both inherit from x, both A and B have a "sub-object" of x. If you upcast from A to x your asking for the address of the sub-object in A. Now if you have an object C that inherits from A(with its sub object x) and B (with it's sub object x) you now have two sub objects in C both with their own separate references to x. Here's where the problem comes in, if you then try to upcast to X from C... which sub object do you use? That will cause ambiguity errors. That's what happens in C++. Java takes the "interface/implements" approach to avoid such problems. What I don't understand is the use for even Java's version of multiple inheritance. I'm still struggling with that chapter of the TIJ book.