Why is the disable back button code not working in Android?

I want to disable the back button for my android app. All I want to do is, when the user presses the back button, nothing should happen. Basically like return false in JavaScript. The following is the code that I have in my MainActivity that I am using currently:

package com.ws.gostock;

import android.os.Bundle;
import org.apache.cordova.*;

public class MainActivity extends CordovaActivity
{
   @Override
   public void onCreate(Bundle savedInstanceState)
   {
      super.onCreate(savedInstanceState);
      // Set by <content src="index.html" /> in config.xml
      loadUrl(Config.getStartUrl());
   }

   @Override
   public void onBackPressed()
   {
      System.out.println("back pressed");
   }
}

Tried to run in debug mode, What happens is, when I press the back button the app closes, and then the code starts to debug. I don't know why.

I fixed the problem.. here is the code that I used:

public void onCreate(Bundle savedInstanceState)
{
    super.onCreate(savedInstanceState);
    // Set by <content src="index.html" /> in config.xml
   loadUrl(Config.getStartUrl());
   
   appView.setOnKeyListener(new View.OnKeyListener() 
   { 
       public boolean onKey(View v, int keyCode, KeyEvent event) 
       {
           if (event.getAction() == KeyEvent.ACTION_UP) 
           {
               if(keyCode == KeyEvent.KEYCODE_BACK) 
               {
                   if(t == null)
                   {
                       t = new Timer();
                       t.schedule(new reInitializeTimer(), 0, 1*1000);
                       Toast.makeText(getApplicationContext(), " Press Back again to Exit ", Toast.LENGTH_SHORT).show();
                   }
                   else if(backpress >= 1)
                   {
                       finish();
                   }
                   
                   return true;
               }
               return onKeyUp(keyCode, event);
           }
           return onKeyDown(keyCode, event); 
       } 
  });
}

class reInitializeTimer extends TimerTask
{
    public void run()
    {
        backpress++;
        if(backpress > 3)
        {
            backpress = 0;
            t.cancel();
            t = null;
        }
    }
}