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Android : AlertDialog

Tutorial by:      Date: 2016-05-10 05:01:29

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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
 
  1. <RelativeLayout xmlns:androclass="http://schemas.android.com/apk/res/android"  
  2.     xmlns:tools="http://schemas.android.com/tools"  
  3.     android:layout_width="match_parent"  
  4.     android:layout_height="match_parent"  
  5.     tools:context=".MainActivity" >  
  6.   
  7.     <TextView  
  8.         android:layout_width="wrap_content"  
  9.         android:layout_height="wrap_content"  
  10.         android:layout_centerHorizontal="true"  
  11.         android:layout_centerVertical="true"  
  12.         android:text="@string/hello_world" />  
  13.   
  14. </RelativeLayout>  

strings.xml

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

File: strings.xml
 
  1. <?xml version="1.0" encoding="utf-8"?>  
  2. <resources>  
  3.   
  4.     <string name="app_name">alertdialog</string>  
  5.     <string name="hello_world">Hello world!</string>  
  6.     <string name="menu_settings">Settings</string>  
  7.     <string name="dialog_message">Welcome to Alert Dialog</string>  
  8.    
  9.    <string name="dialog_title">Javatpoint Alert Dialog</string>  
  10. </resources>  

Activity class

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

File: MainActivity.java
 
  1. package com.example.alertdialog;  
  2.   
  3. import android.os.Bundle;  
  4. import android.app.Activity;  
  5. import android.app.AlertDialog;  
  6. import android.content.DialogInterface;  
  7. import android.view.Menu;  
  8.   
  9. public class MainActivity extends Activity {  
  10.   
  11.     @Override  
  12.     protected void onCreate(Bundle savedInstanceState) {  
  13.         super.onCreate(savedInstanceState);  
  14.           
  15.         AlertDialog.Builder builder = new AlertDialog.Builder(this);  
  16.         //Uncomment the below code to Set the message and title from the strings.xml file  
  17.         //builder.setMessage(R.string.dialog_message) .setTitle(R.string.dialog_title);  
  18.           
  19.         //Setting message manually and performing action on button click  
  20.         builder.setMessage("Do you want to close this application ?")  
  21.             .setCancelable(false)  
  22.             .setPositiveButton("Yes"new DialogInterface.OnClickListener() {  
  23.                 public void onClick(DialogInterface dialog, int id) {  
  24.                 finish();  
  25.                 }  
  26.             })  
  27.             .setNegativeButton("No"new DialogInterface.OnClickListener() {  
  28.                 public void onClick(DialogInterface dialog, int id) {  
  29.                 //  Action for 'NO' Button  
  30.                 dialog.cancel();  
  31.              }  
  32.             });  
  33.   
  34.         //Creating dialog box  
  35.         AlertDialog alert = builder.create();  
  36.         //Setting the title manually  
  37.         alert.setTitle("AlertDialogExample");  
  38.         alert.show();  
  39.         setContentView(R.layout.activity_main);  
  40.     }  
  41.   
  42.     @Override  
  43.     public boolean onCreateOptionsMenu(Menu menu) {  
  44.         // Inflate the menu; this adds items to the action bar if it is present.  
  45.         getMenuInflater().inflate(R.menu.activity_main, menu);  
  46.         return true;  
  47.     }  
  48.   

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