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Java applet displays JLabel (and other components) with extra random letters

When I run the applet whose code is below, the text JLabeldoes not display correctly. Additional garbage symbols are added above the text of the inscription.

If I omit the call setFont(), I see no problems with rendering.

The applet works fine in appletviewer, but has these rendering artifacts in Chrome, Firefox, and IE 8. I am running the latest version of Java 6 (version 25) on Windows XP. The problem seems to always occur in Chrome and breaks in Firefox.

Do you have any ideas on what might be causing this? I guess I'm doing something stupid.

I posted the compiled applet here: http://evanmallory.com/bug-demo/ .

package com.evanmallory;

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

public class TellTime extends JApplet {

    private JLabel mMessage;

    public TellTime() {
        mMessage = new JLabel("Set the clock to the given time.",
            SwingConstants.CENTER);
        mMessage.setFont(new Font("Serif", Font.PLAIN, 36));
        getContentPane().add(mMessage);
    }

}

Here is a screenshot of how it looks to me:

enter image description here

+3
2

, GUI Swing EDT.

. 1 ()

package com.evanmallory;

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

public class TellTime extends JApplet {

    private JLabel mMessage;

    public TellTime() {
        SwingUtilities.invokeLater( new Runnable() {
            public void run() {
                mMessage = new JLabel("Set the clock to the given time.",
                    SwingConstants.CENTER);
                mMessage.setFont(new Font("Serif", Font.PLAIN, 36));
                getContentPane().add(mMessage);
            }
        });
    }
}

. 2 ( , )

( ), setFont(), Timer, , repaint().

// <applet code="AppletBasic" width="300" height="100"></applet>
// The above line makes it easy to test the applet from the command line by using:
// appletviewer AppletBasic.java

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

public class AppletBasic extends JApplet
{
    Timer timer;

    /**
     * Create the GUI. For thread safety, this method should
     * be invoked from the event-dispatching thread.
     */
    private void createGUI()
    {
        final JLabel appletLabel = new JLabel( "I'm a Swing Applet" );
        appletLabel.setHorizontalAlignment( JLabel.CENTER );

        ActionListener listener = new ActionListener() {
            Random random = new Random();
            public void actionPerformed(ActionEvent ae) {
                // determine a size between 12 & 36.
                int size = random.nextInt(24)+12;
                appletLabel.setFont(new Font("Serif", Font.PLAIN, size));
                // tell the applet to repaint
                repaint();
            }
        };
        timer = new Timer(500, listener);
        timer.start();

        add( appletLabel );
    }

    public void init()
    {
        try
        {
            SwingUtilities.invokeAndWait(new Runnable()
            {
                public void run()
                {
                    createGUI();
                }
            });
        }
        catch (Exception e)
        {
            System.err.println("createGUI didn't successfully complete: " + e);
        }
    }
}

.

<html>
<body>
<applet codebase="classes" code="com.evanmallory.TellTime.class"
  width=800 height=500>
    <param name="level" value="1"/>
    <param name="topic" value="TellTime"/>
    <param name="host" value="http://localhost:8080"/>
  </applet>
  </body>
</html>
  • codebase="classes" . Java, /classes ( /lib) .
  • , com.evanmallory.TellTime.class com.evanmallory.TellTime.
  • <param name="host" value="http://localhost:8080"/> WAG, , . Applet.getDocumentBase() Applet.getCodeBase().

BTW - FF, Oracle Java. EDT (), .

+2

Swing GUI init():

// <applet code="AppletBasic.class" width="400" height="400"></applet>
// The above line makes it easy to test the applet from the command line by using:
// appletviewer AppletBasic.java

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

public class AppletBasic extends JApplet
{
    /**
     * Create the GUI. For thread safety, this method should
     * be invoked from the event-dispatching thread.
     */
    private void createGUI()
    {
        JLabel appletLabel = new JLabel( "I'm a Swing Applet" );
        appletLabel.setHorizontalAlignment( JLabel.CENTER );
        add( appletLabel );
    }

    public void init()
    {
        try
        {
            SwingUtilities.invokeAndWait(new Runnable()
            {
                public void run()
                {
                    createGUI();
                }
            });
        }
        catch (Exception e)
        {
            System.err.println("createGUI didn't successfully complete: " + e);
        }
    }

}

:

+1

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