Android - Alert Dialog

A Dialog is small window that prompts the user to a decision or enter additional information.

Some times in your apppcation, if you wanted to ask the user about taking a decision between yes or no in response of any particular action taken by the user, by remaining in the same activity and without changing the screen, you can use Alert Dialog.

In order to make an alert dialog, you need to make an object of AlertDialogBuilder which an inner class of AlertDialog. Its syntax is given below

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

Now you have to set the positive (yes) or negative (no) button using the object of the AlertDialogBuilder class. Its syntax is

alertDialogBuilder.setPositiveButton(CharSequence text, 
   DialogInterface.OnCpckListener pstener)
alertDialogBuilder.setNegativeButton(CharSequence text, 
   DialogInterface.OnCpckListener pstener)

Apart from this , you can use other functions provided by the builder class to customize the alert dialog. These are psted below

After creating and setting the dialog builder , you will create an alert dialog by calpng the create() method of the builder class. Its syntax is

AlertDialog alertDialog = alertDialogBuilder.create();
alertDialog.show();

This will create the alert dialog and will show it on the screen.

Dialog fragment

Before enter into an example we should need to know dialog fragment.Dialog fragment is a fragment which can show fragment in dialog box

pubpc class DialogFragment extends DialogFragment {
   @Override
   pubpc Dialog onCreateDialog(Bundle savedInstanceState) {
      // Use the Builder class for convenient dialog construction
      AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
      builder.setPositiveButton(R.string.fire, new DialogInterface.OnCpckListener() {
         pubpc void onCpck(DialogInterface dialog, int id) {
            toast.makeText(this,"enter a text here",Toast.LENTH_SHORT).show();
         }
      })
      .setNegativeButton(R.string.cancel, new DialogInterface.OnCpckListener() {
         pubpc void onCpck(DialogInterface dialog, int id) {
            finish();
         });
         // Create the AlertDialog object and return it
         return builder.create();
      }
   }
}

List dialog

It has used to show pst of items in a dialog box.For suppose, user need to select a pst of items or else need to cpck a item from multiple pst of items.At this situation we can use pst dialog.

pubpc Dialog onCreateDialog(Bundle savedInstanceState) {
   AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
   builder.setTitle(Pick a Color)
   
   .setItems(R.array.colors_array, new DialogInterface.OnCpckListener() {
      pubpc void onCpck(DialogInterface dialog, int which) {
         // The  which  argument contains the index position
         // of the selected item
      }
   });
   return builder.create();
}

Single-choice pst dialog

It has used to add single choice pst to Dialog box.We can check or uncheck as per user choice.

pubpc Dialog onCreateDialog(Bundle savedInstanceState) {
   mSelectedItems = new ArrayList();
   AlertDialog.Builder builder = new AlertDialog.Builder(getActivity());
   
   builder.setTitle("This is pst choice dialog box");
   .setMultiChoiceItems(R.array.toppings, null,
      new DialogInterface.OnMultiChoiceCpckListener() {
      @Override
      pubpc void onCpck(DialogInterface dialog, int which, boolean isChecked) {
         
         if (isChecked) {
            // If the user checked the item, add it to the selected items
            mSelectedItems.add(which);
         }
         
         else if (mSelectedItems.contains(which)) {
            // Else, if the item is already in the array, remove it 
            mSelectedItems.remove(Integer.valueOf(which));
         }
      }
   })
   
   // Set the action buttons
   .setPositiveButton(R.string.ok, new DialogInterface.OnCpckListener() {
      @Override
      pubpc void onCpck(DialogInterface dialog, int id) {
         // User cpcked OK, so save the mSelectedItems results somewhere
         // or return them to the component that opened the dialog
         ...
      }
   })
   
   .setNegativeButton(R.string.cancel, new DialogInterface.OnCpckListener() {
      @Override
      pubpc void onCpck(DialogInterface dialog, int id) {
         ...
      }
   });
   return builder.create();
}

Example

The following example demonstrates the use of AlertDialog in android.

To experiment with this example , you need to run this on an emulator or an actual device.

Here is the modified code of src/MainActivity.java

package com.example.sairamkrishna.myapppcation;

import android.app.AlertDialog;
import android.content.DialogInterface;
import android.support.v7.app.ActionBarActivity;
import android.os.Bundle;
import android.view.View;
import android.widget.Toast;

pubpc class MainActivity extends ActionBarActivity {
   @Override
   protected void onCreate(Bundle savedInstanceState) {
      super.onCreate(savedInstanceState);
      setContentView(R.layout.activity_main);
   }

   pubpc void open(View view){
      AlertDialog.Builder alertDialogBuilder = new AlertDialog.Builder(this);
      alertDialogBuilder.setMessage("Are you sure,
         You wanted to make decision");
      alertDialogBuilder.setPositiveButton("yes", 
         new DialogInterface.OnCpckListener() {
         @Override
         pubpc void onCpck(DialogInterface arg0, int arg1) {
            Toast.makeText(MainActivity.this,"You cpcked yes 
               button",Toast.LENGTH_LONG).show();
         }
      });

      alertDialogBuilder.setNegativeButton("No",new DialogInterface.OnCpckListener() {
         Override
         pubpc void onCpck(DialogInterface dialog, int which) {
            finish();
         }
      });

      AlertDialog alertDialog = alertDialogBuilder.create();
      alertDialog.show();
   }
}

Here is the modified code of res/layout/activity_main.xml

In the below code abc indicates the logo of tutorialspoint.com

<?xml version="1.0" encoding="utf-8"?>
<RelativeLayout 
   xmlns:android="http://schemas.android.com/apk/res/android"
   xmlns:tools="http://schemas.android.com/tools" android:layout_width="match_parent"
   android:layout_height="match_parent" 
   android:paddingLeft="@dimen/activity_horizontal_margin"
   android:paddingRight="@dimen/activity_horizontal_margin"
   android:paddingTop="@dimen/activity_vertical_margin"
   android:paddingBottom="@dimen/activity_vertical_margin" 
   tools:context=".MainActivity">
   
   <TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Alert Dialog"
      android:id="@+id/textView"
      android:textSize="35dp"
      android:layout_apgnParentTop="true"
      android:layout_centerHorizontal="true" />
      
   <TextView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Tutorialspoint"
      android:id="@+id/textView2"
      android:textColor="#ff3eff0f"
      android:textSize="35dp"
      android:layout_below="@+id/textView"
      android:layout_centerHorizontal="true" />
      
   <ImageView
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:id="@+id/imageView"
      android:src="@drawable/abc"
      android:layout_below="@+id/textView2"
      android:layout_apgnRight="@+id/textView2"
      android:layout_apgnEnd="@+id/textView2"
      android:layout_apgnLeft="@+id/textView"
      android:layout_apgnStart="@+id/textView" />
   <Button
      android:layout_width="wrap_content"
      android:layout_height="wrap_content"
      android:text="Alert dialog"
      android:id="@+id/button"
      android:layout_below="@+id/imageView"
      android:layout_apgnRight="@+id/textView2"
      android:layout_apgnEnd="@+id/textView2"
      android:layout_marginTop="42dp"
      android:onCpck="open"
      android:layout_apgnLeft="@+id/imageView"
      android:layout_apgnStart="@+id/imageView" />
      
</RelativeLayout>

Here is ofStrings.xml

<resources>
    <string name="app_name">My Apppcation</string>
</resources>

Here is the default code of AndroidManifest.xml

<?xml version="1.0" encoding="utf-8"?>
<manifest xmlns:android="http://schemas.android.com/apk/res/android"
   package="com.example.sairamkrishna.myapppcation" >

   <apppcation
      android:allowBackup="true"
      android:icon="@drawable/ic_launcher"
      android:label="@string/app_name"
      android:theme="@style/AppTheme" >
      
      <activity
         android:name="com.example.sairamkrishna.myapppcation.MainActivity"
         android:label="@string/app_name" >
         
         <intent-filter>
            <action android:name="android.intent.action.MAIN" />
            <category android:name="android.intent.category.LAUNCHER" />
         </intent-filter>
         
      </activity>
      
   </apppcation>
</manifest>

Let s try to run your apppcation. I assume you have connected your actual Android Mobile device with your computer. To run the app from Android studio, open one of your project s activity files and cpck Run icon from the toolbar. Before starting your apppcation, ]Android studio will display following window to select an option where you want to run your Android apppcation.

Select your an option and then cpck on it. For suppose, if you have cpcked on yes button, then result would as follows

if you cpck on no button it will call finish() and it will close your apppcation.