Printing causes gdi leakage?

Question

Hi!
I have a problem when printing a lot of reports to the printer. I'm using java 1.5.0
running under Windows2003. I set up a nul printer (or pause my default printer)and run the
code below, and watch the gdi objects count (via Taskmanager) increase and increase and...
When it reaches 10000 the desktop will be messed up and my app stops printing.
How do I end a printerjob to avoid this????
Any help is appreciated,
Regards
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.print.PageFormat;
import java.awt.print.Printable;
import java.awt.print.PrinterException;
import java.awt.print.PrinterJob;
import javax.swing.JFrame;
* @author janne
* To change the template for this generated type comment go to
* Window>Preferences>Java>Code Generation>Code and Comments
public class PTest extends JFrame implements Printable
     class TestPrn extends Thread
          public boolean stop = false;
          private PTest frame;
          public TestPrn(PTest frame)
               this.frame = frame;
          public void stopMe()
               stop = true;
          public void run()
               while (!stop)
                    PrinterJob printerJob = PrinterJob.getPrinterJob();
                    printerJob.setPrintable(new PTest());
                    try
                         printerJob.print();
                    catch (Exception e)
                    try
                         Thread.sleep(1000);
                    catch (Exception e)
     private TestPrn pt;
     private javax.swing.JPanel jContentPane = null;
     private javax.swing.JButton jButton = null;
     static public PTest o = null;
     private javax.swing.JButton jButton1 = null;
      * This is the default constructor
     public PTest()
          super();
          initialize();
      * This method initializes this
      * @return void
     private void initialize()
          this.setSize(300, 200);
          this.setContentPane(getJContentPane());
          this.setTitle("PTest");
          this.addWindowListener(new java.awt.event.WindowAdapter()
               public void windowClosing(java.awt.event.WindowEvent e)
                    System.exit(0);
      * This method initializes jContentPane
      * @return javax.swing.JPanel
     private javax.swing.JPanel getJContentPane()
          if (jContentPane == null)
               jContentPane = new javax.swing.JPanel();
               jContentPane.setLayout(new java.awt.BorderLayout());
               jContentPane.add(getJButton(), java.awt.BorderLayout.SOUTH);
               jContentPane.add(getJButton1(), java.awt.BorderLayout.CENTER);
          return jContentPane;
      * This method initializes jButton
      * @return javax.swing.JButton
     private javax.swing.JButton getJButton()
          if (jButton == null)
               jButton = new javax.swing.JButton();
               jButton.setText("Start");
               jButton.addActionListener(new java.awt.event.ActionListener()
                    public void actionPerformed(java.awt.event.ActionEvent e)
                         pt = o.new TestPrn(o);
                         pt.start();
          return jButton;
     /* (non-Javadoc)
      * @see java.awt.print.Printable#print(java.awt.Graphics, java.awt.print.PageFormat, int)
     public int print(Graphics graphics, PageFormat format, int pageIndex) throws PrinterException
          System.out.println("In print");
          /* We'll assume that Jav2D is available.
          //          Graphics2D g2d = (Graphics2D) graphics;
          /* Move the origin from the corner of the Paper to the corner
           * of the imageable area.
          //          g2d.translate(format.getImageableX(), format.getImageableY());
          //          g2d.draw3DRect(10,10,100,500,true);
          //          return 0;
          graphics.dispose();
          return Printable.NO_SUCH_PAGE;
      * This method initializes jButton1
      * @return javax.swing.JButton
     private javax.swing.JButton getJButton1()
          if (jButton1 == null)
               jButton1 = new javax.swing.JButton();
               jButton1.setText("Stop");
               jButton1.addActionListener(new java.awt.event.ActionListener()
                    public void actionPerformed(java.awt.event.ActionEvent e)
                         if (pt != null)
                              pt.stopMe();
                              try
                                   Thread.sleep(1000);
                              catch (Exception ee)
                              pt = null;
          return jButton1;
public static void main(String[] args)
     o = new PTest();
     o.setVisible(true);
}

Answer 1

Hi,
I used to get serious GDI and memory leakage in my Swing apps.
If you "program like a C++ programmer" you won't get it....
ie.
1. explicitely remove components from containers when you're finished.
In fact I wrote a recursive function to start at a JFrame and recursively remove
all Swing components from it.
2. explicitely remove all listeners, actionlisterers, mouselisteners etc..
They hold references to your Swing components, and stop them from being
garbage collected. So, that nasty habit of yours to use anonymous classes
as actionlisteners must stop ! I prefer to let the class, in your case PTest,
implement the actionlisteners, and then just call addActionListener(this).
So, my guess is, it's not to do with the Printing as such.
regards,
Owen