Cycling 74 » Topic: multiple class inheritance

multiple class inheritance

Olivier Pasquet — Fri, 04 Jul 2008 19:57:28 +0000

Hello there !

I’m trying to make :
public class antsimulation extends MaxObject extends SimState {

In Java, I can only do :
public class antsimulation extends MaxObject {

“extends SimState” is not allowed… I have tryed something like
“implements SimState” but it does not work.

O..///

Re: multiple class inheritance

Emmanuel Jourdan — Fri, 04 Jul 2008 20:16:50 +0000

On 4 juil. 08, at 21:57, olivier pasquet wrote:

> Hello there !
>
> I’m trying to make :
> public class antsimulation extends MaxObject extends SimState {
>
> In Java, I can only do :
> public class antsimulation extends MaxObject {
>
> “extends SimState” is not allowed… I have tryed something like
> “implements SimState” but it does not work.

As far as I remember a class can only herite from one class. You
probably want to use an interface.

Re: multiple class inheritance

Olivier Pasquet — Fri, 04 Jul 2008 20:26:22 +0000

> As far as I remember a class can only herite from one class. You
probably want to use an interface.
< yes, indeed. cheers.

I’m trying to make :
public class antsimulation extends MaxObject extends SimState {

In Java, I can only do :
public class antsimulation extends MaxObject {

Instead, you should use :
public class antsimulation extends MaxObject {
public interface SimState{

That’s all.

Re: multiple class inheritance

Adam Murray — Fri, 04 Jul 2008 20:56:18 +0000

Yup, no multiple inheritance in Java. Interfaces are the standard alternative, but you could end up implementing the same interface the same way in multiple places. Redundant code is very bad…

So keep in mind inheritance is not the only way to share code between classes. By composing objects (just stick one object inside another as a member variable), you can get many of the same benefits of multiple inheritance. Google for “composition vs inheritance” if the idea isn’t clear.