Android AlertDialog Example

Android AlertDialog can be used to display the dialog message with OK and Cancel buttons. It can be used to interrupt and ask the user about his/her choice to continue or discontinue.

Android AlertDialog is composed of three regions: title, content area and action buttons.

Android AlertDialog is the subclass of Dialog class.

Android AlertDialog Example

Let's see a simple example of android alert dialog.

activity_main.xml

You can have multiple components, here we are having only a textview.

File: activity_main.xml

<RelativeLayout xmlns:androclass="http://schemas.android.com/apk/res/android"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    tools:context=".MainActivity" >

    <TextView
        android:layout_width="wrap_content"
        android:layout_height="wrap_content"
        android:layout_centerHorizontal="true"
        android:layout_centerVertical="true"
        android:text="@string/hello_world" />

</RelativeLayout>

strings.xml

Optionally, you can store the dialog message and title in the strings.xml file.

File: strings.xml

<?xml version="1.0" encoding="utf-8"?>
<resources>

    <string name="app_name">alertdialog</string>
    <string name="hello_world">Hello world!</string>
    <string name="menu_settings">Settings</string>
    <string name="dialog_message">Welcome to Alert Dialog</string>
 
   <string name="dialog_title">Javatpoint Alert Dialog</string>
</resources>

Activity class

Let's write the code to create and show the AlertDialog.

File: MainActivity.java

package com.example.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);
		
		AlertDialog.Builder builder = new AlertDialog.Builder(this);
		//Uncomment the below code to Set the message and title from the strings.xml file
		//builder.setMessage(R.string.dialog_message) .setTitle(R.string.dialog_title);
		
		//Setting message manually and performing action on button click
		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.activity_main, menu);
		return true;
	}

}

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