侦听器出错（尝试从具有接口的asynctask返回值）

Question

I want to return a value from an asynctask to main ui (not a message).

The best and simple solution that I found it was https://github.com/levinotik/ReusableAsyncTask/tree/master/src/com/example from another post.

However the asynctask.setOnResultsListener(this) asFtp in my code call give me an error in Eclipse:

The method setOnResultsListener(ResultsListener) in the type MainActivity.asFTP is not applicable for the arguments ( new View.OnClickListener(){} )

I think suppose/imagine the problem, but how solves it in the simplest way?

Button btn_copiar = (Button) findViewById(R.id.btn_copiar);
btn_copiar.setOnClickListener(new OnClickListener(){
public void onClick (View v) {
    try {
        asFtp = new asFTP();
        if (comprobar_preferencias()){
        Log.d(TAG, prefServidor + " " + String.valueOf(prefPuerto) + " " + prefUsuario + " " + prefPass);
        asFtp.setOnResultsListener(this); // here I get the eclipse error
        asFtp.execute();

Thanks.

Answer 1

First, when you reference this inside the creation of a new object, this refers to that object.

You are saying that the onClickListener is the ResultListener. I am going to guess that the class in which you create the onClickListener is the class that implements the onResultListener interface.

So for example if you have

public class MyClass {
    private int test;

    public void example() {
         // this refers to MyClass here (the current scope)
         this.test = 0;
         OnClickListener listener = new View.OnClickListener() {
              // Now we are in the intalization of a new Object.
              // "this" refers to the OnClickListener that you are creating
         }
    }
}

So for example, in this case, if you wanted to refer to MyClass in the creation block of the OnClickListener, you simply need to reference the name of the class. So for example:

public class MainActivity extends Activity implements OnReultsListener {
    private int test;

    public void example() {
         this.test = 0;
         OnClickListener listener = new View.OnClickListener() {
               asFtp = new asFTP();
               asFtp.setOnClickListener(MainActivity.this)'
               ... whatever else you need ...
         }
    }
}

In your case, you would have something like

Button btn_copiar = (Button) findViewById(R.id.btn_copiar);
btn_copiar.setOnClickListener(new OnClickListener(){
public void onClick (View v) {
   try {
       asFtp = new asFTP();
       if (comprobar_preferencias()){
          Log.d(TAG, prefServidor + " " + String.valueOf(prefPuerto) + " " + prefUsuario + " " + prefPass);
    asFtp.setOnResultsListener(MainActivity.this); // here I get the eclipse error
    asFtp.execute();

EDIT: I know this example is crude, I just wanted to get the point across. Let me know if you have any questions.