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Message Box in Windows Store App

Posted by Mahesh Chand Articles | Windows Store Apps January 04, 2013
How to show a message box in a Windows Store app using the MessageDialog class.
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Message Dialogs in Window Store apps are the equivalent of Message Boxes in classic Windows. In this article, we will learn how to display a message box in a Windows Store app using the MessageDialog class. 

The MessageDialog class is used to create and display a message dialog. This class is defined in the namespace "Windows.UI.Popups". You must import the Windows.UI.Popups namespace before using the MessageDialog class, as in:

using Windows.UI.Popups; 

Creating a MessageDialog

The MessageDialog class has two constructors. The first constructor takes a single string type parameter, the message to be displayed and the second constructor takes two parameters, the message and the title of the dialog.

The following code snippet creates two message dialogs.

var messageDialog = new MessageDialog("Hello Windows Store App.");
var messageDialog2 = new MessageDialog("Hello Windows Store App.", "Hello Windows");

The first line of code creates a MessageDialog with a message. The second line of the code creates a MessageDialog with a message and title.

Content and Title

The Content property represents the text message to be displayed. The following code snippet sets and gets the content of a message dialog:

messageDialog.Content = "Hello Windows Store App.";
string message = messageDialog.Content; 

The Title property represents the title of the dialog that appears in the title bar. The following code snippet sets and gets the title of a message dialog:

messageDialog.Title = "Hello Windows";
string title = messageDialog.Title;

Commands

Buttons are a very important part of a message dialog if your application expects an input from a user. OK, Cancel, Yes, and No buttons are typical message dialog buttons. The MessageDialog class has a command bar that can support up to three commands. The Commands property is used to add and read commands.

The following code snippet adds two commands to the command bar of a MessageDialog:

// Add commands and set their callbacks. You can create a single callback 
// Or create a separate callback for different commands

messageDialog.Commands.Add(new UICommand("OK", new UICommandInvokedHandler(this.CommandInvokedHandler)));
messageDialog.Commands.Add(new UICommand("Close", new UICommandInvokedHandler(this.CommandInvokedHandler)));

Command Index

The MessageDialog class has the DefaultCommandIndex and CancelCommandIndex properties that are used to set the default button and cancel button sequence, as in:

// Set CommandIndex. 0 means default.
messageDialog.DefaultCommandIndex = 0;
messageDialog.CancelCommandIndex = 1; 

Show MessageDialog

The ShowAsync method is used to display a message dialog. The ShowAsync method is an asynchronous method and must have an await keyword when calling it. The caller method must be an async method. For example:

// Show MessageDialog

await messageDialog.ShowAsync();

Complete Sample Code

The code listed in Listing 1 is a button click event handler that displays a message dialog with two buttons, OK and Close with a command event handler.

private async void OpenFileButtonClick(object sender, RoutedEventArgs e)
{

    // Create a MessageDialog
    var messageDialog = new MessageDialog("Hello Windows Store App.");
    // Or create a separate callback for different commands

    messageDialog.Commands.Add(new UICommand(
        "OK", new UICommandInvokedHandler(this.CommandInvokedHandler)));
    messageDialog.Commands.Add(new UICommand(
        "Close", new UICommandInvokedHandler(this.CommandInvokedHandler))); 

    // Set CommandIndex. 0 means default.
    messageDialog.DefaultCommandIndex = 0;
    messageDialog.CancelCommandIndex = 1; 

    // Show MessageDialog
    await messageDialog.ShowAsync();

} 

private void CommandInvokedHandler(IUICommand command)
{
    // Do something here on the command handler
}

Listing 1

The code listed in Listing 1 generates a message dialog that looks as in Figure 1.

 Windows-Store-Message-Dialog.png

Figure 1

Summary

In this article, I demonstrated how to display a message box in a Windows Store app using the MessageDialog class. 

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