Android Alert Dialog Box Tutorial

Introduction of Alert Dialog Box Control

Situation : Everyone uses javascript confirm() function. This function display a message with user choice to yes or no. Same functionality in android achieved by alert dialog.

Android provides confirm functionality using alert dialog box. For using this feature we need to createAlertDialog.Builder object. In this we pass Current context.

AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(context);

Using this object we set following properties of this dialog.

1. setTitle() : This function is used to set title of alert dialog box.
   
   

   Syntex :
   
   alertDialogBuilder.setTitle("Your Title");
   

2. setCancelable () : This functionis used for cancellation of alert dialog box. We can set true or falsevalues.
   
   

   Syntex :
   
   alertDialogBuilder.setCancelable(false);
   

3. setPositiveButton() : This function create a button with desired text. In our syntex("Yes"). If user click this button alert event which is attached to it triggered.
   
   

   Syntex :
   

   alertDialogBuilder.setPositiveButton("Yes",new DialogInterface.OnClickListener() {
   					

   public void onClick(DialogInterface dialog,int id) {
               //  Task to perform
               
               
   					}
   				});
   
   

4. setNegativeButton() : This function create a button with desired text. In our syntex("No"). If user click this button alert event which is attached to it triggered or cancel the alert dialog box.
   
   

   Syntex :
   
   alertDialogBuilder.setNegativeButton("No",new DialogInterface.OnClickListener() {
   					

   public void onClick(DialogInterface dialog,int id) {
   						

   // if this button is clicked, just close
   						

   // the dialog box and do nothing
   						

   dialog.cancel();
   					}
   				});
   

After setting above properties we use create() method to create alert dialog.

Syntex :

AlertDialog alertDialog = alertDialogBuilder.create();

At last step we show this alert dialog box. using show() method.

Syntex :

alertDialog.show();

Example

1. Make layout file which contains a button. If we click on button it show alert dialog.
   
   

   <?xml version="1.0" encoding="utf-8"?>
   
   <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
   
       android:layout_width="fill_parent"
   
       android:layout_height="fill_parent"
   
       android:orientation="vertical" >
   
      
   
   
       <Button
   
           android:id="@+id/buttonToast"
   
           android:layout_width="wrap_content"
   
           android:layout_height="wrap_content"
   
           android:text="Show Alert Box" />
   
   </LinearLayout>
   

2. Then apply onclick event in mainactivity.class
   
   

   public class MainActivity extends Activity {
    
   	final Context context = this;
   	private Button button;
    
   	public void onCreate(Bundle savedInstanceState) {
    
   		super.onCreate(savedInstanceState);
   		setContentView(R.layout.main);
    
   		button = (Button) findViewById(R.id.buttonAlert);
    
   		// add button listener
   		button.setOnClickListener(new OnClickListener() {
    
   		@Override
   		public void onClick(View arg0) {
    
   			

   AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(

   				context);
    
   			

   // set title
   

     alertDialogBuilder.setTitle("Your Title");
    
   			

   // set dialog message
   			

      alertDialogBuilder.setMessage("Click yes to exit!")
   		     .setCancelable(false)
   		     

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

   public void onClick(DialogInterface dialog,int id) {
   						

   // if this button is clicked, close
   						

   // current activity
   						

   MainActivity.this.finish();
   					}
   				  })
   				

   .setNegativeButton("No",new DialogInterface.OnClickListener() {
   					

   public void onClick(DialogInterface dialog,int id) {
   						

   // if this button is clicked, just close
   						

   // the dialog box and do nothing
   						

   dialog.cancel();
   					}
   				});
     
   				// create alert dialog
   				

   AlertDialog alertDialog = alertDialogBuilder.create();
    
   				

   // show it
   				

   alertDialog.show();
   			}
   		});
   	}
   }
   
   

3. Output :