Advanced Android AsyncTask Callback example

AsyncTaskActivity.java

package com.cesarferreira.asynctaskcallback;

import android.app.Activity;
import android.os.Bundle;
import android.widget.Toast;


public class MainActivity extends Activity {

    @Override
    protected void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);

        SomeTask someTask = new SomeTask(getApplicationContext(), new OnEventListener<String>() {
            @Override
            public void onSuccess(String result) {
                Toast.makeText(getApplicationContext(), "SUCCESS: "+result, Toast.LENGTH_LONG).show();
            }

            @Override
            public void onFailure(Exception e) {
                Toast.makeText(getApplicationContext(), "ERROR: " + e.getMessage(), Toast.LENGTH_LONG).show();
            }
        });
        someTask.execute();
    }

}

OnEventListener.java

package com.cesarferreira.asynctaskcallback;

/**
 * Created by cesarferreira on 30/05/14.
 */
public interface OnEventListener<T> {
    public void onSuccess(T object);
    public void onFailure(Exception e);
}

SomeTask.java

package com.cesarferreira.asynctaskcallback;

import android.content.Context;
import android.os.AsyncTask;

/**
 * Created by cesarferreira on 22/05/14.
 */
public class SomeTask extends AsyncTask<Void, Void, String> {

    private OnEventListener<String> mCallBack;
    private Context mContext;
    public Exception mException;


    public SomeTask(Context context, OnEventListener callback) {
        mCallBack = callback;
        mContext = context;
    }

    @Override
    protected String doInBackground(Void... params) {

        try {
            // todo try to do something dangerous
            return "HELLO";

        } catch (Exception e) {
            mException = e;
        }

        return null;
    }

    @Override
    protected void onPostExecute(String result) {
        if (mCallBack != null) {
            if (mException == null) {
                mCallBack.onSuccess(result);
            } else {
                mCallBack.onFailure(mException);
            }
        }
    }
}

like!

Thanks a lot!

Very Decent Approach.

how to unit test?

This SomeTask leaks context because there's no cancellation.

Clean