How to inherit from multiple base classes in Java? [duplicate]

This question already has answers here: Closed 12 years ago.

Possible Duplicates:

Cheat single inheritance in Java !!

Why is Multiple Inheritance not allowed in Java or C#?

Multiple Inheritance in java.

I know that we can use interfaces to inherit from multiple classes but is it possible to inherit the state as w开发者_运维百科ell?

How can I inherit methods with definitions from 2 classes and have them in a third class in Java?

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Multiple inheritance is not allowed in Java. Use delegates and interfaces instead

public interface AInterface {
        public void a();
}
public interface BInterface {
    public void b();
}

public class A implements AInterface {
    public void a() {}
}
public class B implements BInterface {
    public void b() {}
}

public class C implements AInterface, BInterface {
    private A a;
    private B b;

    public void a() {
        a.a();
    }
    public void b() {
        b.b();
    }
}

Since Java 8 it's possible to use Default Methods in Interfaces.

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Short answer: You can't. Java only has multiple inheritance of interfaces.

Slightly longer answer: If you make sure the methods you care about are in interfaces, then you can have a class that implements the interfaces, and then delegates to instances of the "super classes":

interface Noisy {
  void makeNoise();
}


interface Vehicle {
  void go(int distance);
}

class Truck implements Vehicle {
  ...
}

class Siren implements Noisy {
  ...
}

class Ambulance extends Truck implements Noisy {
  private Siren siren = new Siren();

  public makeNoise() {
    siren.makeNoise();
  }

  ...
}

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You can not, Java doesn't support multiple inheritance. What you could do is composition.

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Java explicitly disallows multiple inheritance of implementation. You're left with using interfaces and composition to achieve similar results.