Sample generic AsyncTask class

sampleactivity.java

package com.yourdomain.yourapp;

public class YourActivity extends Activity {
	
	public void makeServiceCall() {
		OnPostExecuteListener listener = new OnPostExecuteListener() {
			
			public void onPostExecute(String result) {
				// do something with the result
			}
		};
		String url = "http://www.yourapi.com/your_endpoint";
		new ServiceTask(listener).execute(url);
	}

}

sampleasynctask.java

package com.yourdomain.yourapp;

import android.os.AsyncTask;

public class ServiceTask extends AsyncTask<String, Void, String> {
	
	OnPostExecuteListener listener = null;
	
	public ServiceTask(OnPostExecuteListener listener) {
		this.listener = listener;
	}

	@Override
	protected String doInBackground(String... params) {
		String url = params[0];
		String data = ServiceHelper.get(url);
		return data;
	}
	
	@Override
	protected void onPostExecute(String result) {
		if(listener != null)
			listener.onPostExecute(result);
	}
	
	public interface OnPostExecuteListener {
		public void onPostExecute(String result);
	}

}