Source code cara membuat Alert dialog di Android

/*Code java :

package com.example.tampilanalertdialog;

import android.support.v7.app.ActionBarActivity;

import android.os.Bundle;

import android.view.Menu;

import android.view.MenuItem;

import android.app.AlertDialog;

import android.content.DialogInterface;

import android.widget.Button;

import android.widget.Toast;

import android.view.View;

public class AlertActivity extends ActionBarActivity implements View.OnClickListener {

      Button pesanToast;

      Button keluar;

      @Override

      protected void onCreate(Bundle savedInstanceState) {

            super.onCreate(savedInstanceState);

            setContentView(R.layout.activity_alert);

           

            pesanToast=(Button)findViewById(R.id.toast);

            pesanToast.setOnClickListener(this);

           

            keluar=(Button)findViewById(R.id.exit);

            keluar.setOnClickListener(this);

           

      }

      public void onClick(View view){

            if(view==pesanToast){

                  Toast.makeText(this, "Anda Memilih Tampilan Toast", Toast.LENGTH_SHORT).show();

                  }

                  else if(view==keluar){

                  AlertDialog.Builder builder = new AlertDialog.Builder(this);

                  builder.setMessage("Apakah Anda Yakin..?”!“ ingin keluar?")

                  .setCancelable(false)

                  .setPositiveButton("Ya",new DialogInterface.OnClickListener() {

                  public void onClick(DialogInterface dialog,int id) {

                        AlertActivity.this.finish();}

                        })

                        .setNegativeButton("Tidak",new DialogInterface.OnClickListener() {

                                    public void onClick(DialogInterface dialog, int id) {

                                    dialog.cancel();}}).show();

                        }

      }

      @Override

      public boolean onCreateOptionsMenu(Menu menu) {

            // Inflate the menu; this adds items to the action bar if it is present.

            getMenuInflater().inflate(R.menu.alert, menu);

            return true;

      }

      @Override

      public boolean onOptionsItemSelected(MenuItem item) {

            // Handle action bar item clicks here. The action bar will

            // automatically handle clicks on the Home/Up button, so long

            // as you specify a parent activity in AndroidManifest.xml.

            int id = item.getItemId();

            if (id == R.id.action_settings) {

                  return true;

            }

            return super.onOptionsItemSelected(item);

      }

}

 /*code Xml */
<?xml version="1.0" encoding="utf-8"?>

<LinearLayout

    xmlns:android="http://schemas.android.com/apk/res/android"

    android:orientation="vertical"

    android:layout_width="fill_parent"

    android:layout_height="fill_parent" >

<Button android:layout_width="fill_parent"

    android:text="~Tampilkan Toast"

    android:id="@+id/toast"

    android:layout_height="wrap_content">

    </Button>

  <Button

      android:layout_width="fill_parent"

      android:layout_height="wrap_content"

      android:text="~Keluar Sekarang"

      android:id="@+id/exit"></Button>

 </LinearLayout>