Develop Reference

Bouncing balls won't pause

all
What I'm trying to do is to create a bouncing balls java program. Which I did. Each time the user presses start balls will populate the screen. the only problem I'm having is that I don't know how to pause it. Any help would be appreciated. I tried adding something similar to how I did the addball function but don't know how to apply that to pause the ball. I have tried to do the puase function by adding the button pause but don't know how to get it working
BounceFrame:
import java.awt.BorderLayout;
import java.awt.Container;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class BounceFrame extends JFrame {
private static final long serialVersionUID = 1L;
private BallComponent ballComponent;
public BounceFrame() {
setTitle("Bounce");
ballComponent = new BallComponent();
add(ballComponent, BorderLayout.CENTER);
JPanel buttonPanel = new JPanel();
// Adds more balls.
addButton(buttonPanel, "Start", new ActionListener() {
public void actionPerformed(ActionEvent ae) {
addBall();
}
});
addButton(buttonPanel, "Pause", new ActionListener() {
public void actionPerformed(ActionEvent ae) {
}
});
// Closes the panel.
addButton(buttonPanel, "Close", new ActionListener() {
public void actionPerformed(ActionEvent ae) {
System.exit(0);
}
});
add(buttonPanel, BorderLayout.SOUTH);
pack();
}
public void addButton(Container c, String title, ActionListener listener) {
JButton b = new JButton(title);
c.add(b);
b.addActionListener(listener);
}
public void addBall() {
Ball b = new Ball(ballComponent.getBounds());
RunnableBall rB = new RunnableBall(b, ballComponent);
Thread t = new Thread(rB);
t.start();
}
}
RunnableBall:
import java.util.logging.Level;
import java.util.logging.Logger;
public class RunnableBall implements Runnable {
private Ball b;
private BallComponent comp;
private static final int DELAY = 3; //Controls speed of the balls.
public RunnableBall(Ball b, BallComponent comp)
{
this.b = b;
this.comp = comp;
}
#Override
public void run() {
comp.add(b);
while (true)
{
b.move(comp.getBounds());
comp.repaint();
try
{
Thread.sleep(DELAY);
}
catch (InterruptedException ex) {
Logger.getLogger(RunnableBall.class.getName()).log(Level.SEVERE, null, ex);
}
}
}
}

When you add the ball you need to store the RunnableBall object you are creating in some collection variable, such as a variable of type ArrayList<RunnableBall>, for example. Then in your Pause button's ActionListener you can loop through the ArrayList and call a pause method on each of your RunnableBalls.
So you'll need to then define a pause method inside RunnableBall, which sets a boolean variable "isPaused" to true. So then you'll need to create that variable, isPaused, inside the RunnableBall class, and make it change the behaviour of the run method. You should be able to figure that bit out.
One thing you'll need to take care with is the fact that because you're using multiple threads, you'll need the communication between those threads (i.e. the process of setting the isPaused variable to true or false) to be thread-safe. I think you could achieve that by declaring the isPaused variable to be volatile, but there are other ways to do it.

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

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.

How can I convert a swing JTextField component in to an object of a type that extends it

I have an application using a third party package that has a factory that returns to me JTextField objects that are then added to a GUI. This makes up about 10% of the JTextFields used.
I can't change the third party package but have a requirement to add right click (cut, copy and paste) options in to all ofthe fields.
Now I have a RightClickTextField that extends JTextField and has all the functionality built in to it, this serves to solve my issue for 90% of the application.
However for the 10% that's using the third party package to get JTextFields I cannot think of a solution that will allow me to declare the fields as RightClickTextFields yet use the factory I have to get back the Boxes. I know I cannot cast the result as the objects returned are not of a type that high up in the hierarchy, and a copy constructor won't work since I cannot copy every property being set by the factory, but I don't know of a way to upcast the JTextField in to my type. Is there one?

Rather than subclassing or trying to cast it, can you put your right-click functionality into its own class which implements the MouseInputListener interface, and simply add an instance of your right-click handler to the JTextField objects in question?

Maybe use the Decorator Pattern. This way you can stop using RightClickTextField at all - start using RightClickTextFieldDecorator and supply it either with your own JTextFields or the ones you get from 3rd party thingy.

Thanks for all the comments. I think the actual answer to my question is:
You can't.
Whilst all of the suggestions are valid, I knew it was possible to do all those things, I just wanted to know if I could do it my way first.
My solution (based on feedback here and my own preference) was to create this class below, and manage and expose a single instance of it from a singleton.
I'd appreciate thoughts on this solution?
import java.awt.Component;
import java.awt.Dimension;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseAdapter;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import java.util.HashMap;
import java.util.Map;
import javax.swing.JMenuItem;
import javax.swing.JPopupMenu;
import javax.swing.text.JTextComponent;
public class CopyPasteTextComponentPopoupMenu extends JPopupMenu implements
ActionListener {
private JTextComponent lastInvoker;
private JMenuItem cutMenuItem;
private JMenuItem copyMenuItem;
private JMenuItem pasteMenuItem;
private Map<JTextComponent, JTCProperties> managedComponents;
private MouseListener heyListen;
public CopyPasteTextComponentPopoupMenu() {
super();
init();
}
public CopyPasteTextComponentPopoupMenu(String label) {
super(label);
init();
}
#Override
public void show(Component invoker, int x, int y) {
JTCProperties props = managedComponents.get(invoker);
if(props!=null) {
this.lastInvoker = (JTextComponent) invoker;
setEnabled(props);
super.show(invoker, x, y);
} else {
this.lastInvoker = null;
}
}
public void manageTextComponent(JTextComponent jtc, boolean canCut,
boolean canCopy, boolean canPaste) {
jtc.addMouseListener(heyListen);
JTCProperties props = new JTCProperties(canCut,canCopy,canPaste);
managedComponents.put(jtc,props);
}
public void dispose() {
for (JTextComponent component : managedComponents.keySet()) {
component.removeMouseListener(heyListen);
managedComponents.remove(component);
}
}
#Override
public void actionPerformed(ActionEvent e) {
if (lastInvoker != null) {
if (e.getSource() == cutMenuItem) {
lastInvoker.cut();
} else if (e.getSource() == copyMenuItem) {
lastInvoker.copy();
} else if (e.getSource() == pasteMenuItem) {
lastInvoker.paste();
}
}
}
private void setEnabled(JTCProperties props) {
cutMenuItem.setEnabled(props.canCut);
copyMenuItem.setEnabled(props.canCopy);
pasteMenuItem.setEnabled(props.canPaste);
}
private void init() {
this.managedComponents = new HashMap<JTextComponent, JTCProperties>();
this.setPreferredSize(new Dimension(100, 70));
cutMenuItem = new JMenuItem("Cut");
copyMenuItem = new JMenuItem("Copy");
pasteMenuItem = new JMenuItem("Paste");
cutMenuItem.addActionListener(this);
copyMenuItem.addActionListener(this);
pasteMenuItem.addActionListener(this);
this.add(cutMenuItem);
this.add(copyMenuItem);
this.add(pasteMenuItem);
heyListen = new MouseAdapter() {
public void mousePressed(MouseEvent e) {
if (e.isPopupTrigger()) {
show(e.getComponent(), e.getX(), e.getY());
}
}
public void mouseReleased(MouseEvent e) {
if (e.isPopupTrigger()) {
show(e.getComponent(), e.getX(), e.getY());
}
}
};
}
private class JTCProperties {
public boolean canCut, canCopy, canPaste;
public JTCProperties(boolean canCut, boolean canCopy, boolean canPaste) {
this.canCut = canCut;
this.canCopy = canCopy;
this.canPaste = canPaste;
}
}
}

Listen to mouse clicks on whole system (not on a JFrame etc.)

I want to write a little code which react to a mouse click. But it seems the only way is to listen to clicks on Java components. A direct listener to all clicks would be great.
Is there actually a possibility to implement this in Java?
Thanks in advance!
Update:
Found out, that it would need a hook via JNI with some C coding.
More information on
http://www.jotschi.de/?p=90
Best regards,
fnst

It's perfectly possible if you are willing to use a third party library - JNativeHook
It provides these functionality using JNI which is otherwise not possible in pure java apps.

Don´t think so, because of the sandbox you´re running in.

some food for thought: use Point in Java to detect where the click occurs. http://download.oracle.com/javase/1.4.2/docs/api/java/awt/Point.html
admittedly, ive only used it once before for detecting rows in a table something like, but it seems the closest to what ive found answering your qn.:
public void mouseClicked(MouseEvent e) {
JTable target = (JTable)e.getSource();
//get the coordinates of the mouse click
Point p = e.getPoint();
//get the row index that contains that coordinate
row= target.rowAtPoint(p);
}
im sorry if this isn't what you're looking for, but otherwise, clicking on components is the only way to go. whats the alternative- clicking on containers? well that just doesn't make any sense does it?

As far as I know, there is not easy way to accomplish what you want. But what you want could be done.. Well for modern way to accomplish this task, I suggest you examine java.awt.Dialog show method..
package mouseclickevent;
import java.awt.AWTEvent;
import java.awt.Component;
import java.awt.EventQueue;
import java.awt.MenuComponent;
import java.awt.Toolkit;
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import java.awt.event.MouseEvent;
import java.lang.reflect.Method;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.JTextField;
public class FrmEvent extends JFrame {
public FrmEvent(){
JPanel panel = new JPanel();
getContentPane().add(panel);
JButton btn = new JButton("Test");
panel.add(btn);
panel.add(new JTextField("Test"));
btn.addActionListener(new ActionListener() {
#Override
public void actionPerformed(ActionEvent e) {
FrmEvent frm = new FrmEvent();
frm.setBounds(300,300, 200, 200);
frm.show();
}
});
}
private void consumeEvents() {
try {
if (Thread.currentThread().getClass().getName().endsWith(
"EventDispatchThread")) {
EventQueue eq = null;
eq = Toolkit.getDefaultToolkit().getSystemEventQueue();
if (eq == null) {
return;
}
while (isVisible() || isShowing()) {
AWTEvent event = eq.getNextEvent();
Object src = event.getSource();
Class kActiveEvent= Class.forName("java.awt.ActiveEvent");
if (kActiveEvent != null) {
if (kActiveEvent.isInstance(event)) {
Method m;
Class types[] = {};
Object args[] = {};
m = kActiveEvent.getMethod("dispatch", types);
if (m != null) {
m.invoke(event, args);
continue;
}
}
}
dispatchEvent(src, event);
}
}
}
catch (Exception e) {
e.printStackTrace();
throw new RuntimeException(e);
}
}
private void dispatchEvent(Object src, AWTEvent event) {
if (event.getID()== MouseEvent.MOUSE_CLICKED) {
System.out.println("mouseClicked");
}
if (src instanceof Component) {
( (Component) src).dispatchEvent(event);
} else if (src instanceof MenuComponent) {
( (MenuComponent) src).dispatchEvent(event);
}
}
public void show(){
super.show();
consumeEvents();
}
public static void main(String[] args) {
FrmEvent frm = new FrmEvent();
frm.setBounds(300,300, 200, 200);
frm.show();
}
}