How do you implement multiple inheritance in JAVA?

How do you implement multiple inheritance in JAVA?

A1- First of all, Java doesn't allow you to have one class extending 2 or more classes. According to the problem you are dealing with, you can have your class to extend another class and implement many interfaces.

But let's say that you have 2 classes A and B already implemented from a library and you want  the class C to "extend from both". What can you do?

The solution A1 doesn't apply to this problem. So let's see other options:

A2- You can extend one class (e.g. C extends A) and write on your class C all non-private members from class B, redirecting them to class B members. E.g:

public class A{

  //...

}

public class B{

    public int bMehtod(int param) {  return (param + 123);   }

}

public class C extends A{

  private B b;

  public C() { this( new B() ); }

  public C(B b) {

       if ( b==null ){

           this.b = new B();

       } else {

            this.b = b;

       }

  }

  

//B members section

    public int bMehtod(int param) {  

return this.b.bMehtod(param);   //just forward the call to B

    }

}