对AsyncTask使用委托

Question

I'm having trouble implementing a delegate in my android app.

In my GetData class I have nested asynctask, and I need to notify my main activity when all the work has actually finished.

I came up with this answer from Mohd Mufiz What is the best way for AsyncTask to notify parent Activity about completion?

But I always get stuck at the same point: in my GetData class I call a constructor with the delegate as only argument:

public class GetData {

    private TaskDelegate delegate;

    public GetData(TaskDelegate delegate) {
        this.delegate = delegate;
    }
...
}

In my main activity I don't know what I have to pass to get it working:

 GetData getData = new GetData(**???**);

Answer 1

Going from the question you linked to, that defined TaskDelegate as :

public interface TaskDelegate {
    public void taskCompletionResult(String result);
}

You can pass GetData any instance of a class that implements TaskDelegate - but typically, that would be the object that creates it - ie. your main activity (and so, therefore, it would also implement "void taskCompletionResult(String result);"). That then means you can pass "this" to GetData's constructor, so :

public class MyMainActivity implements TaskDelegate {

    public void someMethod() {
        GetData getData = new GetData(this);
    }

    public void taskCompletionResult(String result) {
        // do stuff
    }
 }