multiplt inheritence in java

[j srinivas]

i have "A" class in which i define two methods add()and substract().
I have another class "B" in which i declared another two methods multiply()and divide().

Now i have a class "C",in which i want to use all the four methods.

Whether it is possible or not.

[Campbell Ritchie]

"Favour composition over inheritance."

public class A extends B
{
 . . .
private C myC;
 
public void multiply()
{
   myC.multiply();
}

That's one possible way to do it.

[Nisha Puri]

Originally posted by j srinivas:
i have "A" class in which i define two methods add()and substract().
I have another class "B" in which i declared another two methods multiply()and divide().

Now i have a class "C",in which i want to use all the four methods.

Whether it is possible or not.

In java you can not inherit more than one class.
To achieve multiple inheritance, you should use interfaces(in which you can declare methods(definition is not allowed))
class A is fine. Change your class B to interface B, syntax:-
interface B { ....}
and then use following code:-

class C extends A implements B
{
...
...
}
[ May 20, 2008: Message edited by: Nisha Puri ]

[fred rosenberger]

In java you can not inherit more than one class.

Because this comes up occasionally, let me clarify a little. You cannot DIRECTLY extend from more than one class.

[Bill Shirley]

Multiple Inheritance is not possible in Java.

What you are trying to do is possible (in a sense).

public interface Colorable {
 void setColor(String colorname);
 void changeHue();
 String getColor();
}
 
public interface Sizable {
 void setSize(int size);
 void makeBigger();
}
 

public class Car
 implements Colorable, Sizable {
 //...
}
 
public class Paint
 implements Colorable {
 //...
}

(typing off the cuff, any syntax errors are left as an exercise for the reader)

[j srinivas]

thanks all....


but is it really impossible...

[Darryl Burke]

Why don't you try it and see what the compiler tells you?

[joseph prabhu]

Originally posted by j srinivas:
thanks all....


but is it really impossible...

joe here
class A
{ void add(int a,int b){}void subract(int a,int b){}
}
class B extends A
{ void multiply(int a,int b){}void divide(int a,int b){}
}
class c extends b
{ B obj=new B();
obj.add(); obj.subract(); obj.multiply(); obj.divide();

}

[Campbell Ritchie]

That's not called multiple inheritance. You only have each class declaring it extends one class. C extends B and B extends A is called single inheritance.

[Paul Yule]

Originally posted by j srinivas:
but is it really impossible...

Yes, it is impossible. That doesn't mean that the only solution is multiple inheritance... which is the point.
[ May 22, 2008: Message edited by: paul yule ]

[arulk pillai]

Java only supports multiple interface inheritance and does not support multiple inheritance. Favor composition as recommended in the Gang Of Four design patterns.

[Darryl Burke]

Originally posted by arulk pillai:
Java only supports multiple interface inheritance and does not support multiple inheritance. Favor composition as recommended in the Gang Of Four design patterns.

Java supports implementing multiple interfaces. Implementation and inheritance are not the same.