Develop Reference

Java AWT Stops listening to input after random lengths of time

(Sorry I can't get a working E.g. of the issue, I need help for my help!)
I'm in the process of creating a custom game engine and have come upon an issue whereby while the game is running - the game stops taking input
I've checked and the program seems to continue running in the background. It also doesn't seem to vary with different machines
(My main device is a Mac Book Pro 2011)
import java.awt.event.*;
import java.io.IOException;
import java.awt.*;
import javax.swing.*;
public class Focus extends JFrame implements KeyListener {
private static final long serialVersionUID = 1L;
char currKey = '\0';
public static void main(String[] args) throws IOException {
SwingUtilities.invokeLater(new Runnable() {public void run() {new UIManager();}});
}
public Focus() throws IOException {
Container contentPane = getContentPane();
contentPane.add(new DrawCanvas());
addKeyListener(this);
setDefaultCloseOperation(EXIT_ON_CLOSE);
pack();
setFocusable(true);
setVisible(true);
}
private class DrawCanvas extends JPanel {
private static final long serialVersionUID = 1L;
public void paintComponent(Graphics pen) {
//Drawloop
if(currKey == 'k') {
//This is the code that randomly stops running
System.out.println("Yo");
}
try {
Thread.sleep(10);
}
catch (InterruptedException e) {
e.printStackTrace();
}
repaint();
}
}
#Override
public void keyTyped(KeyEvent e) {
currKey = e.getKeyChar();
}
#Override
public void keyPressed(KeyEvent e) {
currKey = '\0';
}
#Override
public void keyReleased(KeyEvent e) {
}
}
The code looks right to me (But then, it always does) and the only possible tripping point is that AWT is Instantiated in Main, Run in UIManager and the movement code resides in player though I don't know enough about AWT to know whether this would be the case and relocating the code in a backup lead to a program crash. Any help would be greatly appreciated.

Turns out it was an issue with Java and MacOS key repeats- fixed in a newer Java version
To fix update java

Java mouse listener: toggle version "click counter"

I'm trying to make a basic click counter using mouse events in Java. I understand the tutorials everyone has but their programs are semi automatic and it registers one increment per click.
public void mouseClicked(MouseEvent e)
{
clicks++;
}
I'm trying to do a fully automatic version of that where it will continually increment until you release the button, but the release method doesn't switch the boolean to false and stop the loop. Any advice?
public class example{
private boolean fire = false;
public void mousePressed(MouseEvent e)
{
if(e.getButton()== e.BUTTON1){fire = true};
while(fire) {clickCounter++; }
}
}
public void mouseReleased(MouseEvent e){
fire = false;
}
}

Just to be clear, a "click" is what typically happens between the mouse been pressed and released, the idea that there are more "clicks" during this period is an artificial construct.
First, you need to go read Concurrency in Swing to better understand while "sleep" and while-loop won't work in this context. You're blocking the Event Dispatching Thread, preventing any new events from been processed.
The following example simply attempts to calculate the time between the mouse pressed and released event and applies a artificial multiplier to the result to create the "click" count
import java.awt.Dimension;
import java.awt.EventQueue;
import java.awt.GridBagLayout;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.time.Duration;
import java.time.LocalDateTime;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
EventQueue.invokeLater(new Runnable() {
#Override
public void run() {
JFrame frame = new JFrame();
frame.add(new TestPane());
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
});
}
public class TestPane extends JPanel {
public TestPane() {
setLayout(new GridBagLayout());
JLabel label = new JLabel("...");
add(label);
addMouseListener(new MouseAdapter() {
private LocalDateTime clickTime;
#Override
public void mouseClicked(MouseEvent e) {
clickTime = LocalDateTime.now();
}
#Override
public void mouseReleased(MouseEvent e) {
if (clickTime == null) {
return;
}
Duration between = Duration.between(clickTime, LocalDateTime.now());
long seconds = between.getSeconds();
long clicks = seconds * 3;
label.setText("Held for " + seconds + "s = " + clicks + " clicks");
clickTime = null;
}
});
}
#Override
public Dimension getPreferredSize() {
return new Dimension(200, 200);
}
}
}
Another solution might be to start a Swing Timer on mouse pressed and stop it on mouse released, allowing it to increment a value

You set fire= true then enter into an infinite while(true) loop.
To fix this, modify the boolean statement of the while loop inside the loop itself.
while(fire) {
count++;
if (mouseReleased(eventMouseIsReleased))
fire= false;
} // Check while(fire) but now it is false! Move on!
Hope this helps!

Java wait code until JFrame keyPressed

I'm using a JFrame and I wanted to display an image and pause the code until the user presses ANY key. After that key being pressed the image would close and the code would continue running.
What I did:
Created a flag
final boolean[] flag = {true};
Added a addKeyListener to the JFrame object that would change the flag
frame.addKeyListener(new KeyListener() {
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyReleased(KeyEvent e) {
}
#Override
public void keyPressed(KeyEvent e) {
frame.setVisible(false);
frame.dispose();
flag[0] = false;
}
});
Wait loop until flagged
while (flag[0]){
try {
Thread.sleep(10);
} catch (InterruptedException e) {
e.printStackTrace();
}
}
This is working, but I understand that it is a bit resourceful.
Is there any other way of making the wait loop? Is there any listener of the listener?
2nd try, using CountDownLatch:
Set the latch
final CountDownLatch latch = new CountDownLatch(1);
CountDown
for (JFrame frame : framesList) {
frame.addKeyListener(new KeyListener() {
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyReleased(KeyEvent e) {
}
#Override
public void keyPressed(KeyEvent e) {
frame.setVisible(false);
frame.dispose();
latch.countDown();
}
});
Wait
latch.await();

So, you want to display an image and have the execution stop until the window is closed. This just screams modal dialog to me. A modal dialog will stop the code execution from where it is made visible, it will do it in such away so as not to block the Event Dispatching Thread and make your entire problem come to a screaming halt and hang the program. See How to use dialogs for more details...
import java.awt.BorderLayout;
import java.awt.Component;
import java.awt.Dialog;
import java.awt.Image;
import java.awt.Window;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.KeyEvent;
import java.awt.image.BufferedImage;
import java.io.File;
import java.io.IOException;
import java.util.List;
import javax.imageio.ImageIO;
import javax.swing.AbstractAction;
import javax.swing.ActionMap;
import javax.swing.ImageIcon;
import javax.swing.InputMap;
import javax.swing.JButton;
import javax.swing.JDialog;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.KeyStroke;
import javax.swing.SwingUtilities;
import javax.swing.SwingWorker;
public class Test {
public static void main(String[] args) {
new Test();
}
public Test() {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
try {
BufferedImage img = ImageIO.read(...);
ImageShower.show(null, img);
} catch (IOException ex) {
ex.printStackTrace();
}
}
});
}
public static class ImageShower extends JPanel {
private JLabel label = new JLabel();
public ImageShower() {
setLayout(new BorderLayout());
add(label);
InputMap im = getInputMap(WHEN_IN_FOCUSED_WINDOW);
ActionMap am = getActionMap();
im.put(KeyStroke.getKeyStroke(KeyEvent.VK_ESCAPE, 0), "close");
am.put("close", new AbstractAction() {
#Override
public void actionPerformed(ActionEvent e) {
Window window = SwingUtilities.windowForComponent(ImageShower.this);
if (window != null) {
window.dispose();
}
}
});
}
public void setImage(Image img) {
label.setIcon(new ImageIcon(img));
}
public static void show(Component owner, Image img) {
Window parent = null;
if (owner != null) {
parent = SwingUtilities.windowForComponent(owner);
}
JButton close = new JButton("Close");
close.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
JButton btn = (JButton) e.getSource();
Window window = SwingUtilities.windowForComponent(btn);
if (window != null) {
window.dispose();
}
}
});
JDialog dialog = new JDialog(parent, Dialog.ModalityType.APPLICATION_MODAL);
ImageShower shower = new ImageShower();
shower.setImage(img);
dialog.add(shower);
dialog.add(close, BorderLayout.SOUTH);
dialog.getRootPane().setDefaultButton(close);
dialog.pack();
dialog.setLocationRelativeTo(owner);
dialog.setVisible(true);
}
}
}
"But wait, may images are large and take time to load and I don't want to freeze the UI while the load"...
Okay, for that, I'd look towards using a SwingWorker, which can load the image in the background but which provides simple methods for ensuring the the image is displayed within the context of the EDT properly...
public class ImageLoadAndShow extends SwingWorker<Void, Image> {
#Override
protected Void doInBackground() throws Exception {
BufferedImage img = ImageIO.read(...);
publish(img);
return null;
}
#Override
protected void process(List<Image> chunks) {
Image img = chunks.get(chunks.size() - 1);
ImageShower.show(null, img);
}
}
Not, if the image fails to load, you won't know about it, as the doInBackground method will pass the Exception out of the method. You'd need to use a combination of a PropertyChangeListener and the SwingWorkers get method to trap it, just remember, get is blocking, so calling it inside the context of the EDT will block until the worker completes
"But I need to carry out other operations when the dialog is closed"
There are a few ways you might be able to achieve this, depending on what it is you want to do, for this example, I've stuck with the SwingWorker, because it was easy to copy and paste the basic structure, but you could use a Runnable wrapped in a Thread
public class ImageLoadShowAndWait extends SwingWorker<Void, Void> {
#Override
protected Void doInBackground() throws Exception {
BufferedImage img = ImageIO.read(...);
SwingUtilities.invokeAndWait(new Runnable() {
#Override
public void run() {
ImageShower.show(null, img);
}
});
return null;
}
}
Now, if none of that does what you want...then I'd like to know what it is you're actually doing :P, have a look at Foxtrot which provides an API which allows you to execute code asynchronisly within the EDT without blocking it (entirly), but which will stop the code execution at the point it's called until it completes
The thing is that I wanted it to close the JFrame when ANY key is pressed
KeyListener is going to give you issues, maybe not today, maybe not tomorrow, but it will blow up in your face eventually. The example I've provide binds the Escape key to dispose of the window. It also makes the "Close" button the default button, which provides Space and/or Enter keys as well and a nice visual queue to the user.
If you want to use KeyListener, that's up to you, but your core problem doesn't seem to revolve around it, but the ability to display a window and pause the code execution till it's closed

JTextField text has to clear when I start typing in it

I have a simple login frame with a JTextField and a JPasswordField. When my frame loads the text of the JTextField is "Typ your login". I want to erase that text when the JTextField gets focus. It's the first element in my frame so it already has focus when I load the frame, but I want it to clear whenever I click on it or start typing in it. I tried a MouseListener, which works fine, but now I'd like to clear the JTextField from the moment I start typing. This is the code involving my problem:
import java.awt.FlowLayout;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JFrame;
import javax.swing.JPasswordField;
import javax.swing.JTextField;
public class TextFields extends JFrame {
private static final long serialVersionUID = 1L;
private JTextField login;
private JPasswordField password;
public TextFields() {
super("Event handling");
setLayout(new FlowLayout());
login = new JTextField("Type your login", 20);
password = new JPasswordField(20);
add(login);
add(password);
LoginHandler handler = new LoginHandler();
login.addMouseListener(handler);
}
private class LoginHandler implements ActionListener, MouseListener {
public void mouseClicked(MouseEvent e) {
login.setText("");
}
#Override
public void mouseEntered(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseExited(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mousePressed(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void mouseReleased(MouseEvent e) {
// TODO Auto-generated method stub
}
#Override
public void focusLost(FocusEvent arg0) {
// TODO Auto-generated method stub
}
}
public static void main(String[] args) {
TextFields test = new TextFields();
test.setDefaultCloseOperation(EXIT_ON_CLOSE);
test.setSize(250, 100);
test.setVisible(true);
}
}

I don't know the canonical answer, but I've used a FocusListener for this issue, by calling selectAll() in the focusGained method. Don't use a MouseListener since this will fail if the user tabs into the field.
e.g.,
private class MyFocusListener extends FocusAdapter {
#Override
public void focusGained(FocusEvent fEvt) {
JTextComponent component = (JTextComponent) fEvt.getSource();
component.selectAll();
}
}
and
login.addFocusListener(new MyFocusListener());

Conceptually, what you really want is to set a “placeholder” or “prompt” for your text field, rather than changing the actual text in the field. Such an abstraction would also give you features like being able to style the prompt a light gray color.
A normal JTextField does not support this, but you could write your own subclass, or use a library. This answer explains how to use the SwingX library to accomplish that. Basically, just import org.jdesktop.swingx.prompt.PromptSupport; and add this line:
PromptSupport.setPrompt("Type your login", login);

JButton stays pressed when focus stolen by JOptionPane

I am new to Swing and I have a situation. I am designing an application that renders the GUI components dynamically based on an xml file input(meta-data) . Now most of my JTextFields have InputVerifier set to them, for validation purpose. The input verifier pops up JOptionPane whenever there is an invalid input.
Now, if a user enter an invalid data and moves ahead and clicks a button on the Panel, then a dialog pops up and the user have to respond to it. but after that also the button does not paint to release state. It still looked like it is pressed but actually it is not. As the whole code is pretty messy, I am putting the problem scenario in the code below:-
What should I do so that the JButton looks unpressed? I would appreciate if the logic is also explained.
Thanks in advance.
package test;
import java.awt.BorderLayout;
import java.awt.Frame;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.InputVerifier;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
public class VerifierTest extends JFrame {
private static final long serialVersionUID = 1L;
public VerifierTest() {
JTextField tf;
tf = new JTextField("TextField1");
getContentPane().add(tf, BorderLayout.NORTH);
tf.setInputVerifier(new PassVerifier());
final JButton b = new JButton("Button");
b.setVerifyInputWhenFocusTarget(true);
getContentPane().add(b, BorderLayout.EAST);
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (b.hasFocus())
System.out.println("Button clicked");
}
});
addWindowListener(new MyWAdapter());
}
public static void main(String[] args) {
Frame frame = new VerifierTest();
frame.setSize(400, 200);
frame.setVisible(true);
//frame.pack();
}
class MyWAdapter extends WindowAdapter {
public void windowClosing(WindowEvent event) {
System.exit(0);
}
}
class PassVerifier extends InputVerifier {
public boolean verify(JComponent input) {
JTextField tf = (JTextField) input;
String pass = tf.getText();
if (pass.equals("Manish"))
return true;
else {
String message = "illegal value: " + tf.getText();
JOptionPane.showMessageDialog(tf.getParent(), message,
"Illegal Value", JOptionPane.ERROR_MESSAGE);
return false;
}
}
}
}

The method verify is actually not a good place to open a JOptionPane.
There are several approaches you could consider to solve your problem:
You want this JOptionPane to appear everytime the textfield looses the focus and the input is incorrect: use a FocusListener on the JTextField and act upon appropriate events
You want this JOptionPane to appear everytime the buttons is pressed: use your ActionListener to do it if the input is incorrect.
Here is a small snippet of the latter option:
import java.awt.BorderLayout;
import java.awt.Frame;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.InputVerifier;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
public class VerifierTest extends JFrame {
private static final long serialVersionUID = 1L;
public VerifierTest() {
final JTextField tf = new JTextField("TextField1");
getContentPane().add(tf, BorderLayout.NORTH);
tf.setInputVerifier(new PassVerifier());
final JButton b = new JButton("Button");
b.setVerifyInputWhenFocusTarget(true);
getContentPane().add(b, BorderLayout.EAST);
b.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
if (!tf.getInputVerifier().verify(tf)) {
JOptionPane.showMessageDialog(tf.getParent(), "illegal value: " + tf.getText(), "Illegal Value",
JOptionPane.ERROR_MESSAGE);
}
if (b.hasFocus()) {
System.out.println("Button clicked");
}
}
});
setDefaultCloseOperation(EXIT_ON_CLOSE);
}
public static void main(String[] args) {
Frame frame = new VerifierTest();
frame.setSize(400, 200);
frame.setVisible(true);
}
class PassVerifier extends InputVerifier {
#Override
public boolean verify(JComponent input) {
final JTextField tf = (JTextField) input;
String pass = tf.getText();
return pass.equals("Manish");
}
}
}
Also consider setting the default close operation of the JFrame instead of adding a window listener (but it is a good approach to use a WindowListener if you want to pop up a dialog asking the user if he is sure he wants to exit your application).

I added a call to SwingUtilities to ensure that the GUI is on the event thread, and I removed your reference to Frame.
The GUI works for me on Windows XP.
import java.awt.BorderLayout;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.InputVerifier;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
import javax.swing.SwingUtilities;
public class VerifierTest implements Runnable {
private static final long serialVersionUID = 1L;
public VerifierTest() {
}
#Override
public void run() {
JFrame frame = new JFrame();
frame.setSize(400, 200);
JTextField tf;
tf = new JTextField("TextField1");
tf.setInputVerifier(new PassVerifier());
frame.getContentPane().add(tf, BorderLayout.NORTH);
final JButton b = new JButton("Button");
b.setVerifyInputWhenFocusTarget(true);
frame.getContentPane().add(b, BorderLayout.EAST);
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (b.hasFocus())
System.out.println("Button clicked");
}
});
frame.addWindowListener(new MyWAdapter());
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new VerifierTest());
}
class MyWAdapter extends WindowAdapter {
#Override
public void windowClosing(WindowEvent event) {
System.exit(0);
}
}
class PassVerifier extends InputVerifier {
#Override
public boolean verify(JComponent input) {
JTextField tf = (JTextField) input;
String pass = tf.getText();
if (pass.equals("Manish"))
return true;
else {
String message = "illegal value: " + tf.getText();
JOptionPane.showMessageDialog(tf.getParent(), message,
"Illegal Value", JOptionPane.ERROR_MESSAGE);
return false;
}
}
}
}

I have added a new mouse listener to the button as below and its seems to be working fine for me now, but I am not sure if it is a good way of rectifying the buttons selection state.
package test;
import java.awt.BorderLayout;
import java.awt.Frame;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.awt.event.WindowAdapter;
import java.awt.event.WindowEvent;
import javax.swing.InputVerifier;
import javax.swing.JButton;
import javax.swing.JComponent;
import javax.swing.JFrame;
import javax.swing.JOptionPane;
import javax.swing.JTextField;
import javax.swing.plaf.basic.BasicButtonListener;
public class VerifierTest extends JFrame {
private static final long serialVersionUID = 1L;
public VerifierTest() {
JTextField tf;
tf = new JTextField("TextField1");
getContentPane().add(tf, BorderLayout.NORTH);
tf.setInputVerifier(new PassVerifier());
final JButton b = new JButton("Button");
b.setVerifyInputWhenFocusTarget(true);
getContentPane().add(b, BorderLayout.EAST);
b.addActionListener(new ActionListener() {
public void actionPerformed(ActionEvent e) {
if (b.hasFocus())
System.out.println("Button clicked");
}
});
b.addMouseListener(new BasicButtonListener(b) {
#Override
public void mouseExited(MouseEvent e) {
((JButton)e.getSource()).getModel().setArmed(false);
((JButton)e.getSource()).getModel().setPressed(false);
}
});
addWindowListener(new MyWAdapter());
}
public static void main(String[] args) {
Frame frame = new VerifierTest();
frame.setSize(400, 200);
frame.setVisible(true);
// frame.pack();
}
class MyWAdapter extends WindowAdapter {
public void windowClosing(WindowEvent event) {
System.exit(0);
}
}
class PassVerifier extends InputVerifier {
public boolean verify(JComponent input) {
JTextField tf = (JTextField) input;
String pass = tf.getText();
if (pass.equals("Manish"))
return true;
else {
final String message = "illegal value: " + tf.getText();
JOptionPane.showMessageDialog(null, message,
"Illegal Value", JOptionPane.ERROR_MESSAGE);
return false;
}
}
}
}

First: all implementations of InputVerifier which open the dialog in verify() are invalid. They violated their contract, API doc:
This method should have no side effects.
with the "should" really meaning "must not". The correct place for side-effects is shouldYieldFocus.
Second: moving the side-effect (showing the message dialog) correctly into the shouldYieldFocus doesn't work as well ... due to a bug (THEY call it feature request ;-), that's older than a decade and in the top 10 RFEs
Being a hack-around a bug, #dareurdrem's mouseListener is as good as any workable hack can get :-)
Update
After playing a bit with different options to hack around the bug, here's another hack - it's as brittle as all hacks are (and doesn't survive a LAF toggle, has to be re-installed if dynamic toggling is required)
For hacking the mouse behaviour the basic approach is to hook into the listener installed by the ui:
find the original
implement a custom listener which delegates most events directly to the original
for pressed events request focus first: if yielded delegate to original, if not do nothing
The last bullet is slightly more involved because focus events can be asynchronous, so we have to invoke the check for being focused. Invoking, in turn, requires to send a release in case nobody objected.
Another quirk is the rootPane's pressed action (for its defaultButton): it's done without respecting any inputVerifiers by unconditionally calling doClick. That can be hacked by hooking into the action, following the same pattern as hooking into the mouseListener:
find the rootPane's pressed action
implement a custom action which checks for a potentially vetoing inputVerifier: delegate to the original if not, do nothing otherwise
The example modified along those lines:
public class VerifierTest implements Runnable {
private static final long serialVersionUID = 1L;
#Override
public void run() {
InteractiveTestCase.setLAF("Win");
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.setSize(400, 200);
JTextField tf = new JTextField("TextField1");
tf.setInputVerifier(new PassVerifier());
frame.add(tf, BorderLayout.NORTH);
final JButton b = new JButton("Button");
frame.add(b);
b.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
System.out.println("Button clicked");
}
});
// hook into the mouse listener
replaceBasicButtonListener(b);
frame.add(new JTextField("not validating, something else to focus"),
BorderLayout.SOUTH);
frame.getRootPane().setDefaultButton(b);
// hook into the default button action
Action pressDefault = frame.getRootPane().getActionMap().get("press");
frame.getRootPane().getActionMap().put("press", new DefaultButtonAction(pressDefault));
frame.setVisible(true);
}
protected void replaceBasicButtonListener(AbstractButton b) {
final BasicButtonListener original = getButtonListener(b);
if (original == null) return;
Hacker l = new Hacker(original);
b.removeMouseListener(original);
b.addMouseListener(l);
}
public static class Hacker implements MouseListener {
private BasicButtonListener original;
/**
* #param original the listener to delegate to.
*/
public Hacker(BasicButtonListener original) {
this.original = original;
}
/**
* Hook into the mousePressed: first request focus and
* check its success before handling it.
*/
#Override
public void mousePressed(final MouseEvent e) {
if (SwingUtilities.isLeftMouseButton(e)) {
if(e.getComponent().contains(e.getX(), e.getY())) {
// check if we can get the focus
e.getComponent().requestFocus();
invokeHandleEvent(e);
return;
}
}
original.mousePressed(e);
}
/**
* Handle the pressed only if we are focusOwner.
*/
protected void handlePressed(final MouseEvent e) {
if (!e.getComponent().hasFocus()) {
// something vetoed the focus transfer
// do nothing
return;
} else {
original.mousePressed(e);
// need a fake released now: the one from the
// original cycle might never has reached us
MouseEvent released = new MouseEvent(e.getComponent(), MouseEvent.MOUSE_RELEASED,
e.getWhen(), e.getModifiers(),
e.getX(), e.getY(), e.getClickCount(), e.isPopupTrigger()
);
original.mouseReleased(released);
}
}
/**
* focus requests might be handled
* asynchronously. So wrap the check
* wrap the block into an invokeLater.
*/
protected void invokeHandleEvent(final MouseEvent e) {
SwingUtilities.invokeLater(new Runnable() {
#Override
public void run() {
handlePressed(e);
}
});
}
#Override
public void mouseClicked(MouseEvent e) {
original.mouseClicked(e);
}
#Override
public void mouseReleased(MouseEvent e) {
original.mouseReleased(e);
}
#Override
public void mouseEntered(MouseEvent e) {
original.mouseEntered(e);
}
#Override
public void mouseExited(MouseEvent e) {
original.mouseExited(e);
}
}
public static class DefaultButtonAction extends AbstractAction {
private Action original;
/**
* #param original
*/
public DefaultButtonAction(Action original) {
this.original = original;
}
#Override
public void actionPerformed(ActionEvent e) {
JRootPane root = (JRootPane) e.getSource();
JButton owner = root.getDefaultButton();
if (owner != null && owner.getVerifyInputWhenFocusTarget()) {
Component c = KeyboardFocusManager
.getCurrentKeyboardFocusManager()
.getFocusOwner();
if (c instanceof JComponent && ((JComponent) c).getInputVerifier() != null) {
if (!((JComponent) c).getInputVerifier().shouldYieldFocus((JComponent) c)) return;
}
}
original.actionPerformed(e);
}
}
/**
* Returns the ButtonListener for the passed in Button, or null if one
* could not be found.
*/
private BasicButtonListener getButtonListener(AbstractButton b) {
MouseMotionListener[] listeners = b.getMouseMotionListeners();
if (listeners != null) {
for (MouseMotionListener listener : listeners) {
if (listener instanceof BasicButtonListener) {
return (BasicButtonListener) listener;
}
}
}
return null;
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new VerifierTest());
}
public static class PassVerifier extends InputVerifier {
/**
* Decide whether or not the input is valid without
* side-effects.
*/
#Override
public boolean verify(JComponent input) {
final JTextField tf = (JTextField) input;
String pass = tf.getText();
if (pass.equals("Manish"))
return true;
return false;
}
/**
* Implemented to ask the user what to do if the input isn't valid.
* Note: not necessarily the best usability, it's mainly to
* demonstrate the different effects on not/agreeing with
* yielding focus transfer.
*/
#Override
public boolean shouldYieldFocus(final JComponent input) {
boolean valid = super.shouldYieldFocus(input);
if (!valid) {
String message = "illegal value: " + ((JTextField) input).getText();
int goAnyWay = JOptionPane.showConfirmDialog(input, "invalid value: " +
message + " - go ahead anyway?");
valid = goAnyWay == JOptionPane.OK_OPTION;
}
return valid;
}
}
}

Actually the real problem is in how the focus system and awt listeners interact. There are a few bugs declared in Java that the developers are going back and forth on who is responsible.
The mouse listener does : processMouseEvent and within that logic, the current FocusOwner is asked to yield Focus. it fails. But because half the event is processed already, the button becomes armed and the focus remains with the field.
I finally saw one developer comment: Don't let the listener proceed if the field is not allowed to lose focus.
For example:
Define a JTextfield with edits to only allow values < 100.
A message pops up when you lose focus.
I overrode my base JButton classes' processMouseEvent(MouseEvent e)
with code:
protected void processMouseEvent(MouseEvent e) {
if ( e.getComponent() != null && e.getComponent().isEnabled() ) { //should not be processing mouse events if it's disabled.
if (e.getID() == MouseEvent.MOUSE_RELEASED && e.getClickCount() == 1) {
// The mouse button is being released as per normal, and it's the first click. Process it as per normal.
super.processMouseEvent(e);
// If the release occured within the bounds of this component, we want to simulate a click as well
if (this.contains(e.getX(), e.getY())) {
super.processMouseEvent(new MouseEvent(e.getComponent(),
MouseEvent.MOUSE_CLICKED,
e.getWhen(),
e.getModifiers(),
e.getX(),
e.getY(),
e.getClickCount(),
e.isPopupTrigger(),
e.getButton()));
}
}
else if (e.getID() == MouseEvent.MOUSE_CLICKED && e.getClickCount() == 1) {
// Normal clicks are ignored to prevent duplicate events from normal, non-moved events
}
else if (e.getID() == MouseEvent.MOUSE_PRESSED && e.getComponent() != null && (e.getComponent().isFocusOwner() || e.getComponent().requestFocusInWindow())) {// if already focus owner process mouse event
super.processMouseEvent(e);
}
else {
// Otherwise, just process as per normal.
if (e.getID() != MouseEvent.MOUSE_PRESSED) {
super.processMouseEvent(e);
}
}
}
}
in the guts of this logic is the simple questions.
Button: Are you already focus owner.
if not: can you(Button) possibly GAIN focus ( remember - shouldYieldFocus() is called on the current focus holder inside the requestFocusInWindow() call and will return false ALWAYS if not valid )
This Also has the side affect of popping up your error dialog!
This logic Stops the Java libraries processMouseEvent logic from processing half an event while the Focus System stops it from completing.
Obviously you'll need this type of logic on all your different JComponents that perform an action on a click.