AlertDialog Example in Android.

MainActitvity.java

package com.mahi.alertdialog;

import android.os.Bundle;
import android.app.Activity;
import android.app.AlertDialog;
import android.content.DialogInterface;
import android.view.Menu;

public class MainActivity extends Activity {

@Override
protected void onCreate(Bundle savedInstanceState) {
super.onCreate(savedInstanceState);
setContentView(R.layout.activity_main);

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

builder.setMessage("Do you want to close this application ?")
        .setCancelable(false)
        .setPositiveButton("Yes", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int id) {
            finish();
            }
        })
        .setNegativeButton("No", new DialogInterface.OnClickListener() {
            public void onClick(DialogInterface dialog, int id) {
            //  Action for 'NO' Button
            dialog.cancel();
         }
        });

//Creating dialog box
        AlertDialog alert = builder.create();
        //Setting the title manually
        alert.setTitle("AlertDialogExample");
        alert.show();
        setContentView(R.layout.activity_main);
}

@Override
public boolean onCreateOptionsMenu(Menu menu) {
// Inflate the menu; this adds items to the action bar if it is present.
getMenuInflater().inflate(R.menu.main, menu);
return true;
}

}

Output: