防止子类覆盖接口

Question

Is there a way to prevent a subclass from overriding the implementation of interface that super class implement.

I want to create a custom view contains a listView in android and implement onScroll listener but when the subclass set onScroll listener on the list. the listener at the super class is never invoked.

Answer 1

Yes, there is.

The final word on that is: final

By declaring a method final you state that subclasses are not allowed to @Override this method (even without annotation that is).

Consider this interface:

interface MyInter  {
   public void foo();

   public String bar();
}

And your class

public class MyClass implements MyInter {

  @Override 
  public final void foo() {
    //Cant touch this
  }

  @Override
  public String bar() {
    return "foo";
  }

}

Now your third class is allowed to extend MyClass - but limited to overriding bar() because foo() is protected by final keyword:

public class Thirs extends MyClass {
   @Override
   public String bar() {
     return "bar";
   }
}

Answer 2

You can add final keyword to do so.

Eg:

public final void foo() {
    ....
}