Passing “this” from Java Interface to another Class

Question

Giving the following class of my android Project :

Preview extends SurfaceView implements SurfaceHolder.Callback

and

A extends Doc

I don't really know how to ask and I know that this is not really good but I want that from Preview, I call an abstract method of Doc. In this Doc's method, I have to call a method of the previous Object of Preview.

This is an example :

From Preview.java :

   Doc _doc = new A();
   private void myMethod() {
       this._doc.process(this)
   }

From A.java :

@Override
public void process(Preview p) {
    p.processA();
}

The problem is that I got an error :

The method process(Preview) in the type Doc is not applicable for the arguments (new Camera.PreviewCallback(){})

However, I can't change this judging by the fact that I want to call the method from Preview. I tried many thing such as cast etc. None of them works.

Thanks for your help !

PS : I am on Eclipse under Windows.

Answer 1

假设您正在从匿名内部类（我认为是Camera.PreviewCallback类型，因此是错误消息）中调用A.process(this) ，则必须编写A.process(Preview.this) ，因为独立的this引用了内部类而不是Preview实例。

Answer 2

The method process(Preview) in the type Doc is not applicable for the arguments (new Camera.PreviewCallback(){})

It simply means you are passing the object of Camera.PreviewCallback but in your method public void process(Preview p) You want an object of Preview .

If you have written this code in side an anonymous class , then this won't point to the Preview class. It will point to the object of inner anonymous class.

Thus you need to write A.process(Preview.this)