Resizable JWS Applet

"Andrew Thompson" <>
3 Oct 2006 05:39:49 -0700
This example shows how to make an *applet* that is
launched using WebStart (JWS), resizable.

The trick lies in understanding that the root component
of an applet launched via JWS is a frame.

Here is example source and JNLP launch file to demonstrate
(note that you can 'try this at home' off the local
filesystem, just put the source & JNLP in the same
directory, and run these commands from that directory..)

javac *.java
jar -cvf resizeapplet.jar *.class
javaws -codebase file:. resizeapplet.jnlp

<launch file - resizeapplet.jnlp>

<?xml version="1.0" encoding="utf-8"?>
<jnlp spec="1.0"
    <title>Resize Applet</title>
    <vendor>Andrew Thompson</vendor>
    Shows how to make a webstarted applet resizable
      <j2se href=""
      <jar href="resizeapplet.jar"/>

</launch file - resizeapplet.jnlp>

<sscce ->
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class ResizeJWSApplet extends JApplet {

  /** If this applet is launched via webstart, the
  root component should be a frame. This stores a
  reference to the root frame so the applet can
  resize and set its attributes.*/
  Frame root = null;

  public void init() {
    Component parent = getParent();
    while(parent.getParent()!=null) {
      parent = parent.getParent();
    if (parent instanceof Frame) {
      root = (Frame)parent;

    Container c = getContentPane();
    c.setLayout(new GridLayout(0,1));

    // add some buttons to resize the applet
    for (int ii=0; ii<3; ii++) {
      final int value = 100+(100*((int)Math.pow(2,ii)));
      JButton b = new JButton("size " + value);
      b.addActionListener(new ActionListener() {
        public void actionPerformed(ActionEvent ae) {
          setAppletSize(new Dimension (value,value) );

    JButton resizable = new JButton("Toggle Resizable");
    resizable.addActionListener( new ActionListener() {
      public void actionPerformed(ActionEvent ae) {
        if (root!=null) {


  /** Sets whether the frame hosting this applet is
  resizable by the end user. */
  public void setAppletResizeable(boolean resizable) {
    if (root!=null) {

  /** Uses the reference to the root. */
  public void setAppletSize(Dimension size) {
    if (root!=null) {
</sscce ->

( Note - X-posted tc c.l.j.programmer/gui, with follow-ups
to c.l.j.p. only. )

Andrew T.

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