protected Dialog onCreateDialog (int id)

package com.skpack.mybackpressed2finish;

import android.app.Activity;
import android.app.AlertDialog;
import android.app.Dialog;
import android.content.DialogInterface;
import android.os.Bundle;
import android.view.View;
import android.view.View.OnClickListener;
import android.widget.Button;
import android.widget.LinearLayout;
import android.widget.Toast;

public class MyBackpressed2finishActivity extends Activity {
    /** Called when the activity is first created. */
    static final int DIALOG_PAUSED_ID = 0;
    @Override 
    protected Dialog onCreateDialog (int id)
    {
       AlertDialog.Builder builder = new AlertDialog.Builder(this);
       builder.setMessage("Are you sure you want to exit?")
              .setCancelable(false)
              .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
                  public void onClick(DialogInterface dialog, int id) {
                   MyBackpressed2finishActivity.this.finish();
                  }
              })
              .setNegativeButton("No", new DialogInterface.OnClickListener() {
                  public void onClick(DialogInterface dialog, int id) {
                       dialog.cancel();
                  }
              });
       AlertDialog alert = builder.create();
       return alert;
    }

    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        LinearLayout layout = new LinearLayout(this);
        Button button = new Button(this);
        button.setText("I'm So great Button");
        button.setOnClickListener(new OnClickListener(){
           @Override
           public void onClick(View v) {
              showDialog(DIALOG_PAUSED_ID);
           }
        });
        layout.addView(button);
        setContentView(layout);
    }
 /*
 
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.main);
    }
    
    @Override
    public void onBackPressed()  
    //ÎÞÒâÖа´·µ»Ø¼üʱҪÊÍ·ÅÄÚ´æ  
    {  
        // TODO Auto-generated method stub  
     Toast.makeText(this,"bye bye", Toast.LENGTH_LONG).show();
        super.onBackPressed();
        
        this.finish();  
        System.exit(0);  
    }
    */
}