BaseAsyncTask.java

package com.example.yatatsu.simpletodo.task;

import android.os.AsyncTask;

/**
 * simple abstract wrapper for AsyncTask
 * @author yatatsu
 */
public abstract class BaseAsyncTask<T1, T2, T3> extends AsyncTask<T1, T2, T3> {

    public interface Listener<T3> {
        void onSuccess(T3 result);
        void onError(String error);
        void onCancelled();
    }

    private Listener<T3> listener;

    public BaseAsyncTask(Listener<T3> listener) {
        super();
        this.listener = listener;
    }

    protected String getError() {
        return null;
    }

    protected boolean isSuccess() {
        return true;
    }

    public void setListener(Listener<T3> listener) {
        this.listener = listener;
    }

    public Listener<T3> getListener() {
        return listener;
    }

    public void kill() {
        cancel(true);
        setListener(null);
    }

    @Override
    protected void onPostExecute(T3 result) {
        if (listener == null || isCancelled()) {
            return;
        }
        if (isSuccess()) {
            listener.onSuccess(result);
        } else {
            listener.onError(getError());
        }
    }

    @Override
    protected void onCancelled() {
        if (listener != null) {
            listener.onCancelled();
        }
    }
}

exampleActivity.java

public class MainActivity extends AppCompatActivity {
    @Override
    protected void onResume() {
        super.onResume();

        new BaseAsyncTask<String, Void, String>(this) {
            @Override
            protected String doInBackground(String... params) {
                StringBuilder sb = new StringBuilder();
                for (int i = 0, count = params.length; i < count; i++) {
                    sb.append(params[i]);
                    if (i < count - 1) {
                        sb.append(" ");
                    }
                }
                SystemClock.sleep(1000);
                return sb.toString();
            }
        }.execute("A", "B", "C");
    }
    
     @Override
    public void onSuccess(String result) {
        Log.d("RESULT", result); // "A B C";
    }

    @Override
    public void onError(String error) {

    }

    @Override
    public void onCancelled() {

    }
}

How to implement abstract method of this AsyncTask Class ? can you please give me correct and right thing,.? I am trying to implement BaseASyncTask in my project for optimization. And I want to implement abstract method in doInBackground() method of asynctask. I m bit confused in all this.

Sorry for late reply.
I fixed code, and added a usage.
This example is sample, is not suitable for production. (It should be careful of memory leak.)

1. Should not use inner class. (use not inner class or static inner class)
2. kill the task when activity died.(onDestroy() is good)
3. AsyncTask is not for long async operation. (It is for short time and related with UI one)