As you read through the enhancements to the latest release of the J2SE platform, you'll notice immediately that Sun has finally listened to our suggestions. I don't mean to imply that they didn't listen at all in the past, but they seemed to be more focused on adding large-scale APIs than on fixing the ones that have been around for ages. Take for example the AWT Frame class. While Sun added the ability to programmatically iconify the frame in version 1.2, you still couldn't hide the title bar or maximize a frame. While you could use a Window to avoid the title bar, some tasks require a top-level frame, not a window. You were basically out of luck.

Now, with the 1.4 release, you can programmatically hide the platform-specific window decorations, like the title bar, and maximize a frame. Both of these features were first requested back in 1997. The undecorated frame support is a result of an entry in Sun's bug database, bug ID 4038769 from March 1997, and frame zooming support was requested in August 1997 with bug ID 4071554. I'll show you how to use both of these features in this article.

Undecorated frames

The simplest of the two features to use is support for undecorated frames. To hide the title bar on the frame, you need to set the undecorated property of the specific frame to true. By default, the value is false, and you can't change the setting once the frame has been displayed (an IllegalComponentStateException will be thrown if you try).

  Frame frame = new Frame();
  frame.setUndecorated(true);

Because the title bar and other window decorations are now hidden, you can't rely on the underlying window management system to provide support for dragging the frame. You must add this in yourself with a pair of mouse listeners:

  // Avoid creating a point with each mousePressed() call
  Point origin = new Point();
  frame.addMouseListener(new MouseAdapter() {
    public void mousePressed(MouseEvent e) {
      origin.x = e.getX();
      origin.y = e.getY();
    }
  });
  frame.addMouseMotionListener(new MouseMotionAdapter() {
    public void mouseDragged(MouseEvent e) {
      Point p = frame.getLocation();
      frame.setLocation(
        p.x + e.getX() - origin.x, 
        p.y + e.getY() - origin.y);
    }
  });

Back to top

Maximizing frames

Programmatic iconification was added to version 1.2 with the setState() method. Now, with the 1.4 version, there's a setExtendedState() method. This method takes a bitmask flag of the acceptable states, of which there are four. A fifth flag, MAXIMIZED_BOTH, is a combination of two others. The acceptable states are:

• NORMAL -- The normal frame sizing state
• ICONIFIED -- An iconified state
• MAXIMIZED_BOTH -- The maximized frame state (maximized both horizontally and vertically)
• MAXIMIZED_HORIZ -- A horizontal maximized state (may not be supported by windowing environment)
• MAXIMIZED_VERT -- A vertical maximized state (may not be supported by windowing environment)

More often than not, you'll only use the first three states. If you find you need to combine states, like if you want to iconify a frame but preserve its current maximized state, you would use a vertical bar (|) to combine multiple states. Then, once you have the right state, you would use the new setExtendedState() method to change the frame's state.

  // Preserve maximized
  frame.setExtendedState(Frame.ICONIFIED 
    | frame.getExtendedState());

Back to top

A complete example

Here's a complete example that hides the frame's decorations and then adds the window buttons for maximizing, normalizing, iconifying (minimizing), and closing the frame as plain AWT button components. There's also an area available where you can drag the frame around.

import java.awt.*;
import java.awt.event.*;
public class FrameTest {
  static Point origin = new Point();
  public static void main (String args[]) {
    final Frame frame = new Frame();
    frame.setUndecorated(true);
    frame.addMouseListener(new MouseAdapter() {
      public void mousePressed(MouseEvent e) {
        origin.x = e.getX();
        origin.y = e.getY();
      }
    });
    frame.addMouseMotionListener(new MouseMotionAdapter() {
      public void mouseDragged(MouseEvent e) {
        Point p = frame.getLocation();
        frame.setLocation(
          p.x + e.getX() - origin.x, 
          p.y + e.getY() - origin.y);
      }
    });
    frame.setSize(300, 300);
    Button b1 = new Button("Maximize");
    b1.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        frame.setExtendedState(Frame.MAXIMIZED_BOTH);
      }
    });
    Button b2 = new Button("Iconify");
    b2.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        // Preserve maximizing
        frame.setExtendedState(Frame.ICONIFIED 
		   | frame.getExtendedState());
      }
    });
    Button b3 = new Button("Normal");
    b3.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        frame.setExtendedState(Frame.NORMAL);
      }
    });
    Button b4 = new Button("Close");
    b4.addActionListener(new ActionListener() {
      public void actionPerformed(ActionEvent e) {
        System.exit(0);
      }
    });
    frame.setLayout(new GridLayout(5,1));
    frame.add(b1);
    frame.add(b2);
    frame.add(b3);
    frame.add(b4);
    frame.show();
  }
}

Back to top

Download

Information about download methods

Resources

• Read about the AWT enhancements in the Java 2 SDK 1.4 release.
  
  
• Learn to use the AWT Frame with its javadoc.
  
  
• Visit John's client-side Java programming discussion forum on developerWorks to find answers to your client-based questions.
  
  
• Stay on top of cutting-edge Java technology; register for Solutions, the IBM Technical Developer Conference.
  
  
• Read all of John's Magic with Merlin articles.
  
  

About the author

John Zukowski conducts strategic Java consulting with JZ Ventures, Inc. His latest books are Java Collections and Definitive Guide to Swing for Java 2 (2nd ed) from Apress. Contact John at jaz@zukowski.net.

Comments (Undergoing maintenance)

Back to top

Trademarks  |  My developerWorks terms and conditions

Table of contents

• Undecorated frames
• Maximizing frames
• A complete example
• Download
• Resources
• About the author
• Comments

Next steps from IBM

Spring, JRuby, and Ajax development is easier with WebSphere Application Server - a smart Java 5 and J2EE Web services-based application server.

---

• Try: The no-charge WebSphere Application Server Community Edition is a pre-integrated, lightweight Java 5 application server built on Apache Tomcat and other best-of-breed open source software such as OpenEJB, Apache Axis, and Apache Derby.
• Article: The article leverage the Spring Framework and the WebSphere Application Server to improve your J2EE project productivity.
• Tutorial: See how the free WebSphere Application Server and XML can improve the efficiency of your JRuby on Rails and Ajax development.
• Buy: WebSphere Application Server - Express

My developerWorks community

Dig deeper into Java on developerWorks

Rate a product. Write a review.

Write a review for Rational products today!

Special offers