CODEWITHSUNDEEP
javainterface
aps
aps

Reputation: 2472

Enforcing interface implementation in order to use another class

SITUATION: Say there is a class A and an interface B.

REQUIREMENT: If any class, say C, wants to create objects of A and use them, then that class will also have to implement interface B.Is there any way to enforce this condition?

WHY: Now a question may arise as to why I want to do such a thing. The reason is that when a class C creates objects of A and uses them, then those objects call certain methods of C. I want to declare those methods in interface B, so that C will invariably implement those methods.

Upvotes: 0

Views: 1064

Answers (2)

Alex Gitelman
Alex Gitelman

Reputation: 24732

Since you say that objects of class A will call methods on C, they will have to keep reference to C somehow. Make this reference of type B and you are done.

That is

public class A {
  public A(B arg) {
     ....
  }
}

Then in C:

A a = new A(this);

That will force class C to implement interface B.

Upvotes: 0

Prince John Wesley
Prince John Wesley

Reputation: 63708

Try this snippet:

public interface B {
// methods
}

public class A {
   private final B b;
   public A(B b) {
      this.b = b;
   }  
  ...
}

public class C implements B{
   // implement B's methods
   public static void main(String[] arg) {
        C c = new C();
        A a = new A(c);
   }

}

Upvotes: 1

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