This section provides a tutorial example on how to use the static method, showMessageDialog(), to create and display message dialog boxes for 4 different type of messages: information, warning, error, and plain.
The simplest dialog box you can create and display with the javax.swing.JOptionPane class is the message dialog box.
This can be done with the static method: showMessageDialog(frame, message, title, type), where:
"frame" is a frame object to be used as the parent frame.
"message" is the message string to be display on the dialog box.
"title" is the title string to be used as the dialog box title.
"type" is an integer code representing a specific message dialog box type. Valid type codes are predefined
as constants in the JOptionPane class: INFORMATION_MESSAGE, WARNING_MESSAGE, ERROR_MESSAGE and PLAIN_MESSAGE.
Here is an example program I wrote to test the showMessageDialog() method:
/**
* JOptionPaneShowMessageDialog.java
* Copyright (c) 2009 by Dr. Herong Yang, http://www.herongyang.com/
*/
import java.awt.event.*;
import javax.swing.*;
import javax.swing.event.*;
public class JOptionPaneShowMessageDialog implements ActionListener {
JFrame myFrame = null;
public static void main(String[] a) {
(new JOptionPaneShowMessageDialog()).test();
}
private void test() {
myFrame = new JFrame("showMessageDialog Test");
myFrame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
myFrame.setBounds(50,50,250,150);
myFrame.setContentPane(new JDesktopPane());
JMenuBar myMenuBar = new JMenuBar();
JMenu myMenu = getDialogMenu();
myMenuBar.add(myMenu);
myFrame.setJMenuBar(myMenuBar);
myFrame.setVisible(true);
}
private JMenu getDialogMenu() {
JMenu myMenu = new JMenu("Dialogs");
JMenuItem myItem = new JMenuItem("Information");
myItem.addActionListener(this);
myMenu.add(myItem);
myItem = new JMenuItem("Warning");
myItem.addActionListener(this);
myMenu.add(myItem);
myItem = new JMenuItem("Error");
myItem.addActionListener(this);
myMenu.add(myItem);
myItem = new JMenuItem("Plain");
myItem.addActionListener(this);
myMenu.add(myItem);
return myMenu;
}
public void actionPerformed(ActionEvent e) {
String menuText = ((JMenuItem) e.getSource()).getText();
int messageType = JOptionPane.INFORMATION_MESSAGE;
if (menuText.equals("Information")) {
messageType = JOptionPane.INFORMATION_MESSAGE;
} else if (menuText.equals("Warning")) {
messageType = JOptionPane.WARNING_MESSAGE;
} else if (menuText.equals("Error")) {
messageType = JOptionPane.ERROR_MESSAGE;
} else if (menuText.equals("Plain")) {
messageType = JOptionPane.PLAIN_MESSAGE;
}
System.out.println("Before displaying the dialog: "+menuText);
JOptionPane.showMessageDialog(myFrame,
"This is message dialog box of type: "+menuText,
menuText+" Message", messageType);
System.out.println("After displaying the dialog: "+menuText);
}
}
If you run this example, open the "Dialogs" menu,
and click "Information", "Warning" or "Error" menu item,
you will see a message dialog box showing up like this:
Sample programs listed in this section have been tested with JDK 1.6.0.
