Testing shows that JFrames never get garbage collected.
See Comments for more. Also, see attchment for sample code from JFrame test.

Name: mc57594 Date: 12/05/99


java version "1.2.2"
Classic VM (build JDK-1.2.2-W, native threads, symcjit)

The following source code creates a JFrame (called SimpleFrame) that is never
garbage collected. OptimizeIt 3.02 indicates that the frame is being
referenced by an OffScreenImage. Here's the OptimizeIt output:

     References to SimpleFrame SimpleFrame
        c of sun.awt.image.OffScreenImage BufferedImage@3e02230f:

This memory leak happens about 75% of the time when I run this simple program.
Our application has many instances where we are allocating frames that are not
garbage collected. This is the simplest case we could reporduce consistently.

There are two source files: FrameBug.java and SimpleFrame.java:

==================== FrameBug.Java ====================

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public class FrameBug extends JFrame
{
  public FrameBug()
  {
    SimpleFrame simple = new SimpleFrame();
    simple.show();
    simple.dispose();
  }

  public static void main(String[] args)
  {
    FrameBug frame = new FrameBug();

    frame.addWindowListener(new WindowAdapter()
    {
      public void windowClosing(WindowEvent e)
      {
        System.exit(0);
      }
    });

    frame.setVisible(true);
  }
}

==================== SimpleFrame.Java ====================

import javax.swing.*;

public class SimpleFrame extends JFrame
{
  public SimpleFrame()
  {
    setSize(100, 100);
    JPanel panel = new JPanel();
    panel.add(new JLabel("Simple Frame"));
    getContentPane().add(panel);
  }
}
(Review ID: 97683)
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