Changing AWT components to Swing components
I'm having a little trouble changing some AWT components to Swing components. I received an error message when I tried to run my program. I looked up the component in the java docs. But, I did not see the option the error was talking about. The error and the area of code is listed below. Thank you for any help you can provide.
Error message:
Exception in thread "main" java.lang.Error: Do not use P5AWT.setLayout() use P5A
WT.getContentPane().setLayout() instead
at javax.swing.JFrame.createRootPaneException(JFrame.java:446)
at javax.swing.JFrame.setLayout(JFrame.java:512)
at P5AWT.<init>(P5AWT.java:56)
at P5AWT.main(P5AWT.java:133)
Press any key to continue . . .
Code:
JPanel p3 = new JPanel();
p3.setLayout(new FlowLayout(FlowLayout.CENTER));
ta = new JTextArea(20, 60);
p3.add(ta);
setLayout(new FlowLayout(FlowLayout.CENTER));
add(p3);
you need to change the line...
setLayout(new FlowLayout(FlowLayout.CENTER)); to
getContentPane().setLayout(new FlowLayout(FlowLayout.CENTER));
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I shall include the complete html page complete with applet tag to perhaps illuminate a bit more what I mean...
<html>
<head>
<title>Wia Rekenmodule hello!</title>
</head>
<body bgcolor="#C0C0C0">
<applet
CODEBASE= "http://www.creativemathsolutions.nl/test"
ARCHIVE= "Actiz/wia_actiz_archive.jar, Generic/wia_archive.jar"
CODE="WiaRekenToolActiz.class"
WIDTH=915 HEIGHT=555
>
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<PARAM NAME = gebjaar VALUE = "1970">
<PARAM NAME = geslacht VALUE = "man">
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<PARAM NAME = deeltijdpercentage VALUE = "100">
<PARAM NAME = accountnaam VALUE = "Zorginstelling 'De Zonnebloem'">
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</body>
</html> -
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hi all,
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Does Swing/AWT/JFC provides a component hierarchy? can someone share some code on this issue?
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Since I'm a beginner in Swing see my short code below:
import java.awt.BorderLayout;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JMenu;
import javax.swing.JMenuBar;
import javax.swing.JMenuItem;
import javax.swing.JTextArea;
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public EasyFrame() {
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JFrame frame = new JFrame("SwingApplication");
JButton button = new JButton("click here");
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frame.setSize(300, 200);
frame.getContentPane().setLayout(new BorderLayout());
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JMenu menu = new JMenu("A Menu");
menuBar.add(menu);
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menuItem = new JMenuItem("hello");
menu.add(menuItem);
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menu.add(subMenu);
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Uses the JDBC-ODBC Bridge.
Requires a DSN called Autos pointing to Auto.mdb
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import java.awt.*;
import java.awt.event.*;
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addWindowListener(new WindowAdapter()
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System.exit(0);
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add(new JLabel("Manufacturer"));
add(lstManuf);
lstManuf.addItemListener(this);
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add(new JLabel("Model"));
add(lblModel);
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add(lblYear);
add(new JLabel("Cost"));
add(lblCost);
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conVehicle = DriverManager.getConnection("jdbc:odbc:Auto");
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I am advising you to do this because nobody writes code like this (mixing GUI and database and business logic all in one class). So if you want real world training MVC should be what you look at next.
See http://en.wikipedia.org/wiki/Model-view-controller for more
As near as I can tell your problem is mostly just because you aren't using the combo box correctly. Try
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try
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Class.forName ("sun.jdbc.odbc.JdbcOdbcDriver");
catch (ClassNotFoundException err)
//No drivers found
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3) Don't use SELECT *. It is always good practice to put the names of the columns you are selecting. This prevents your code from breaking if the order of the columns should change in any way. -
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though I'm not new to Java but I'm new to displaying different fonts in Swing components.
I have an Swing-based application which is running on a Terminal Server. It works fine for Central, Western und Northern Europe. The next
country to roll out is Greece. So what does a greek user see on his monitor when he uses his greek keyboard?
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Thanks
Dierk.as I wrote, it is a test app to learn how I get greek
fonts on the screen. Of course the real app is used by
greek users who put greek text into the system. In the
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information in different languages.Ah, I see... mind you, I don't think your German text would have a great deal of Cyrillic characters in them, right? Still, it's only a test! ;-)
Now what I'm doing to get my german text in greek
letters is this:
utf8Bytes =
= getorigTextField().getText().getBytes("UTF16");
isr = new InputStreamReader(new
w ByteArrayInputStream
(utf8Bytes), "Cp1253");
As far as I understand, the InputStreamReader gives
the translation
of my german letters in the encoding of CP1253
(Windows Greek). That
means the unicode characters change into the ones of
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so I should be able to show them in a Swing component.This is where your problem is. Java's Strings will always be in UTF-16 when they are held internally. So anything within a textfield is going to be UTF-16 no matter what you do with it.
The line you think is converting to Cp1253 is actually trying to convert from Cp1253 to UTF-16.
Hopefully this is the reason your characters aren't appearing - the unneeded conversion above could be mashing them. Instead, you need expect everything to always be in UTF-16, and to expect to display in it (don't worry, it handles any character you can throw at it, let alone Greek). So then it all comes down to the font you're using.
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Hope that helps!
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Container c = getContentPane();
c.setLayout(new BorderLayout());
sPanel = new JPanel();
ch = new Choice();
for(int i = 0; i < pics.length; ++i) {
ch.add(pics);
scale = new JLabel("Scale");
perc = new JLabel("%");
inPercent = new JTextField(5); // scale value input field
draw = new JButton("Draw");
draw.setBorder(BorderFactory.createEtchedBorder());
draw.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
int index = 0;
index = ch.getSelectedIndex();
pic = null;
repaint();
pic = (Toolkit.getDefaultToolkit().getImage(picsFile[index]));
try{
File f = new File(soundsFile[index]);
sound = Applet.newAudioClip(f.toURL());
}catch(MalformedURLException mfe) {
mfe.printStackTrace();
if(!inPercent.getText().equals("")) {
scaleAm = Integer.parseInt(inPercent.getText()); // get the scale amount from the user
finalScale = ((origScale * scaleAm)/100); // calculate the final scale amount based on what the user entered
}else {
finalScale = origScale; // default to original size of the image if no value for scale was entered
// creates a scaled instance of an image and takes the amount of scale as an argument
repaint();
sound.loop();
muteOn = new JButton("Mute On");
muteOn.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
sound.stop();
muteOn.setText("MuteOff");
sPanel.add(ch);
sPanel.add(scale);
sPanel.add(inPercent);
sPanel.add(perc);
sPanel.add(draw);
sPanel.add(muteOn);
c.add(sPanel, BorderLayout.SOUTH);
repaint();
public void paint(Graphics g) {
if(pic!=null) {
g.drawImage(pic,0,0,this);
public static void main(String args[]) {
ImageViewerAnim app = new ImageViewerAnim();
app.setSize(500,500);
app.setVisible(true);
app.setDefaultCloseOperation(EXIT_ON_CLOSE);
app.show();
thank you in advance
Ivofor future reference
i was able to fix this by adding
super.paint(g);in the first line of my paint method
Ivo -
Issue viewing Swing components
I currently am able to compile, but not view Swing components. I am running Windows Media Center Edition with Radeon X300 graphics card. Swing programs execute but I only see the border window with only grey content inside. I have 1gb of memory and have tried running very small applications with the same effect. Does Java not support my OS? Any ideas?
Some sample code follows that doesn't work for me
At odd times I can see some of the swing applications I try to run, but it isn't consistent. This makes me think it is a memory problem, but I'm not sure. The following application takes 19,040 K with 373688 K available physical memory.
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class DefaultButton {
public static void main(String args[]) {
Runnable runner = new Runnable() {
public void run() {
JFrame frame = new JFrame("DefaultButton");
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setLayout(new GridLayout(2, 2, 10, 10));
JButton button1 = new JButton("Text Button");
button1.setMnemonic(KeyEvent.VK_B);
frame.add(button1);
Icon warnIcon = new ImageIcon("Warn.gif");
JButton button2 = new JButton(warnIcon);
frame.add(button2);
JButton button3 = new JButton("Warning", warnIcon);
frame.add(button3);
String htmlButton = "<html><sup>HTML</sup> <sub><em>Button</em></sub><br>" +
"<font color=\"#FF0080\"><u>Multi-line</u></font>";
JButton button4 = new JButton(htmlButton);
frame.add(button4);
JRootPane rootPane = frame.getRootPane();
rootPane.setDefaultButton(button2);
frame.setSize(300, 200);
frame.setVisible(true);
EventQueue.invokeLater(runner);
} -
Trying to understand "thread-safe" w/ swing components
The other day there was a big hullabaloo about some code I posted because I was calling JLabel.setText from a thread that wasn't the ui thread. On the other hand, this thread was the only thread making changes to the JLabel. My understanding is that in any kind of multi-threaded system, if you just have 1 writer / changer, then no matter how many readers there are, this is thread-safe. So why what I was doing not thread safe?
Second question - JLabel.setText() is essentially setting data in the model for JLabel, which then gets picked up and displayed the next time the GUI thread paints it. So if it's not safe to update a JLabel's model, I assume its never safe to update any data that also is being displayed visually. So for instance, if I was showing some database table data in a JTable, I should do the update in the UI thread - probably not. But what is the distinction?
Third question - what swing components and what operations need to be run on the UI thread to call your program "thread-safe". Validate? setSize()? setLocation()? add? remove? Is there anything that can be called on swing components from a non-ui thread?
Edited by: tjacobs01 on Nov 2, 2008 8:29 PMtjacobs01 wrote:
My understanding is that in any kind of multi-threaded system, if you just have 1 writer / changer, then no matter how many readers there are, this is thread-safe. So why what I was doing not thread safe?This is not true. As I mentioned in that hullabaloo thread, the Java Memory Model allows threads to cache values of variables they use. This means that values written by one thread are not guaranteed to ever be visible to other threads, unless you use proper synchronization.
Take the following example:
import java.util.concurrent.TimeUnit;
public class ThreadExample {
static class Foo {
private String value = "A";
public String getValue() {
return value;
public void setValue(String value) {
this.value = value;
public static void main(String[] args) {
final Foo foo = new Foo();
Thread writer = new Thread() {
@Override
public void run() {
try {
TimeUnit.SECONDS.sleep(1);
foo.setValue("B");
} catch (InterruptedException e) {
e.printStackTrace();
Thread reader = new Thread() {
@Override
public void run() {
try {
TimeUnit.MINUTES.sleep(1);
System.out.println(foo.getValue());
} catch (InterruptedException e) {
e.printStackTrace();
writer.start();
reader.start();
}Here two different threads both access the same Foo instance, which is initialized with a value of "A". One thread, the writer, sleeps one second, and then sets foo's value to "B". The other thread, the reader, sleeps one minute (to avoid race conditions) and then prints foo's value to System.out. It may seem obvious that the reader thread will read the value "B", but this is in fact not guaranteed to be true. The reader thread may never see the value that was written by the writer thread, so it may very well read the old value "A".
(If you run the code you will probably see "B" printed out, but again, this is not guaranteed behavior.)
A simple way to fix this is to synchronize access to the mutable state that the two threads share. For example, change the class Foo to
static class Foo {
private String value = "A";
public synchronized String getValue() {
return value;
public synchronized void setValue(String value) {
this.value = value;
}It's for this same reason that you often see the use of a volatile boolean as a control flag for stopping threads, rather than a plain old boolean. The use of volatile guarantees that the thread you want to stop actually sees the new value of the flag once it has been set by another thread.
Here is an article that touches some of this stuff:
[http://www.ibm.com/developerworks/java/library/j-jtp02244.html]
I also highly recommend the book "Java Concurrency in Practice" (one of the authors of which, David Holmes, sometime hangs out on the Concurrency forum here, I believe).
Edited by: Torgil on Nov 2, 2008 9:01 PM -
How to use Swing Components in JavaFX
Hi All,
I am new to JavaFx. I am trying to use java swing components in javafx.
I found a sample program in net and tried it. But it shows compile time error.
Code:
MySwingComponent .fx
import javafx.ext.swing.SwingComponent;
import javax.swing.JComponent;
import javax.swing.JButton;
import java.awt.event.ActionListener;
import java.awt.event.ActionEvent;
* @author nandha
class MySwingComponent extends SwingComponent{
var button: JButton;
public var text: String on replace {
button.setText(text);
public var action: function();
override protected function createJComponent () : JComponent {
button = new JButton();
button.addActionListener(ActionListener {
public override function actionPerformed(e:ActionEvent){
action();
return button;
The above code shows no error.
Test SwingButton.fx
import javafx.stage.Stage;
import javafx.scene.Scene;
import swingcomponents.MySwingButton;
* @author nandha
Stage {
title: "Swing Button Example"
scene: Scene {
width: 250
height: 80
content: [
MySwingButton{ // error message: imcompatible type. found MySwingButton. Required javafx.scene.Node[]
text: "Click Me!"
action: function(){
println("Hello World!");
This code which used the MySwingButton shows error: imcompatible type. found MySwingButton. Required javafx.scene.Node[] - where i have added the MySwingButton.
Please help me to fix the error.
Thanks &Regards,
Nandha KHi Sasa,
First thanks for your reply.
I found the problem and have fixed.
Problem:
There is no class MySwingButton in the package swingcomponents. Its MySwingComponent that i should have used, which is a big mistake that i have done. To my surprise i don't know NetBeans didn't show any error message at that line.
Thanks & Regards,
Nandha K -
Swing Components and Fullscreen Exclusive
Hi, I am trying to write a program that can switch between full screen and windowed mode seamlessly, while still being able to use standard swing components. I have never worked with the full screen exclusive mode before and am having trouble getting the components to repaint properly.
The following code works fine in the windowed and undecorated modes, however when I switch to fullscreen exclusive mode all components disappear and only repaint upon mouseover or other interaction. Calls to repaint do not make any difference.
import java.awt.Dimension;
import java.awt.DisplayMode;
import java.awt.FlowLayout;
import java.awt.GraphicsDevice;
import java.awt.GraphicsEnvironment;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.WindowConstants;
public class FullscreenTests {
private static boolean hwlast = false;
private static GraphicsDevice dev = GraphicsEnvironment.getLocalGraphicsEnvironment().getDefaultScreenDevice();
public static void main(String[] args) {
final JFrame fMain = new JFrame("Title");
fMain.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);
fMain.getRootPane().setLayout(new FlowLayout());
JButton win = new JButton("Windowed");
win.addActionListener(new ActionListener () {
public void actionPerformed (ActionEvent e) {
setWindowed(fMain);
fMain.getRootPane().add(win);
JButton ful = new JButton("Fullscreen");
ful.addActionListener(new ActionListener () {
public void actionPerformed (ActionEvent e) {
setFullscreen(fMain);
fMain.getRootPane().add(ful);
JButton hw = new JButton("HW Fullscreen");
hw.addActionListener(new ActionListener () {
public void actionPerformed (ActionEvent e) {
setHWFullscreen(fMain);
fMain.getRootPane().add(hw);
setWindowed(fMain);
public static void setWindowed(JFrame f) {
if (hwlast == true) {
dev.setFullScreenWindow(null);
hwlast = false;
f.dispose();
f.setIgnoreRepaint(false);
f.setUndecorated(false);
Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
f.setSize(new Dimension(808,634));
f.setMinimumSize(new Dimension(808,634));
f.setLocation((d.width-f.getWidth())/2, (d.height-f.getHeight())/2);
f.setVisible(true);
public static void setHWFullscreen(JFrame f) {
hwlast = true;
f.dispose();
f.setUndecorated(true);
f.setIgnoreRepaint(true);
f.setVisible(true);
dev.setFullScreenWindow(f);
dev.setDisplayMode(new DisplayMode(800, 600, 32, DisplayMode.REFRESH_RATE_UNKNOWN));
public static void setFullscreen(JFrame f) {
if (hwlast == true) {
dev.setFullScreenWindow(null);
hwlast = false;
f.dispose();
f.setIgnoreRepaint(false);
f.setUndecorated(true);
f.setSize(Toolkit.getDefaultToolkit().getScreenSize());
f.setLocation(0,0);
f.setVisible(true);
}On the same note, if there are better ways of doing this I would be glad to know. This is just a quick test so I haven't done any checks etc when switching to fullscreen exclusive.public static void setHWFullscreen (JFrame f) {
hwlast = true;
f.dispose ();
f.setUndecorated (true);
f.setIgnoreRepaint (true);
// add this
Graphics g = f.getGraphics ();
f.paintAll (g);
f.setVisible (true);
dev.setFullScreenWindow (f);
dev.setDisplayMode (new DisplayMode (800, 600, 32, DisplayMode.REFRESH_RATE_UNKNOWN));
}db
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