Android Popup Custom Layout and Returning (EditText/Textbox) from Dialog

package com.myapp;

import android.os.Bundle;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.view.LayoutInflater;
import android.view.Menu;
import android.view.View;
import android.view.ViewGroup;
import android.widget.Button;
import android.widget.EditText;
import android.widget.TextView;

public class MainActivity extends Activity {
	 
    @Override
    public void onCreate(Bundle savedInstanceState) {
        super.onCreate(savedInstanceState);
        setContentView(R.layout.activity_main);
        
        final AlertDialog.Builder popDialog = new AlertDialog.Builder(this);
        final LayoutInflater inflater = (LayoutInflater) this.getSystemService(LAYOUT_INFLATER_SERVICE);
		
        
        // btnShow
        Button btnShow = (Button) findViewById(R.id.btnShow);
        btnShow.setOnClickListener(new View.OnClickListener() {
            public void onClick(View v) {
            	
                final View Viewlayout = inflater.inflate(R.layout.activity_dialog,
                        (ViewGroup) findViewById(R.id.layout_dialog));                
				
                popDialog.setIcon(android.R.drawable.btn_star_big_on);	
        		popDialog.setTitle("Input User and Password ");
                popDialog.setView(Viewlayout);
                
                // Button OK
                popDialog.setPositiveButton(android.R.string.ok, new DialogInterface.OnClickListener(){

                    public void onClick(DialogInterface dialog, int which) {
                        dialog.dismiss();
                        
                        // txtUsername and Password (Dialog)
                        EditText user = (EditText) Viewlayout.findViewById(R.id.txtUsername);
                        EditText pass = (EditText) Viewlayout.findViewById(R.id.txtPassword);
                        
                        // txtResult (Main Screen)
                        TextView result = (TextView) findViewById(R.id.txtResult);
                        result.setText(" Username : " + user.getText().toString() + " \n" +
                        		" Password : " + pass.getText().toString() + " ");
                        
                    }
                    
                    

                })
                
                // Button Cancel
                .setNegativeButton("Cancel",
  					  new DialogInterface.OnClickListener() {
  					    public void onClick(DialogInterface dialog,int id) {
  						dialog.cancel();
  					    }
  					  });

                popDialog.create();
                popDialog.show(); 
            	
            }	
        });
    }
    
    @Override
    public boolean onCreateOptionsMenu(Menu menu) {
        getMenuInflater().inflate(R.menu.activity_main, menu);
        return true;
    }
   
}