JOptionPane: showMessageDialog

This tutorial describes how to create and display a simple dialog box that displays a message with the JOptionPane.showMessageDialog() method. The simplest message that can be created is achievable by using the class javax.swing.JOptionPane.

showMessageDialog displays a window with a single "OK" button, you can specify the message, the title and the icon with the static method:

showMessageDialog(Component parent, Object message, String title, int typeMessage, Icon icon), or:

parent: is the parent Component (window or panels);
message: is the string message that will be displayed in the JOptionPane;
title: is the title of type string.
typeMessage: this is the type of message of type entire: INFORMATION_MESSAGE, WARNING_MESSAGE, ERROR_MESSAGE and PLAIN_MESSAGE;
icon: is the icon that replaces the default icon;

Here is a practical example to test the showMessageDialog:

import javax.swing.JOptionPane; 

public class MessageDialog {

 public static void main(String[] args) {
 JOptionPane.showMessageDialog(null, 
 "Database has been updated", 
 "Update complete", 
 JOptionPane.INFORMATION_MESSAGE,  
 null); 
 }

}

Result after execution:

Unlike other JOptionPane methods that are functions and return a String or int type, showMessageDialog is a procedure that returns nothing.

We put null in the "parent" argument because the dialog doesn't have a parent. If you don't want to insert an icon, put null in the icon argument box. The compiler displays the default icon based on the message type.

References
Java Doc: showMessageDialog method
java2s: Using JOptionPane to Display a Message: JOptionPane Dialog