Develop Reference

keylistener wait for input

I want to write a live search using Swing components. I am using a keyListener to keep track of the input. Basically i dont want the keyListener to take action every time a button is pressed but instead wait (for some period of time) for more incoming input. This period of time is refreshed every time a button is pressed and the input gets evaluated when it eventually times out (e.g. no button is being pressed within the period meaning that the input is complete). How do I implement that into my keyListener?
Code snippet of main method:
static JTextField nameTextField = new JTextField();
public static void main(String args[]) throws Exception {
JFrame frame = new JFrame();
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.add(nameTextField, BorderLayout.NORTH);
nameTextField.addKeyListener(new KeyListener() {
public void keyTyped(KeyEvent keyEvent) {
//
}
#Override
public void keyPressed(KeyEvent e) {
//
}
#Override
public void keyReleased(KeyEvent e) {
if(waitForMoreInput(50)) {
doSomething(nameTextField.getText());
}
}
}
}
}
);
frame.setSize(250, 100);
frame.setVisible(true);
}
Thanks in advance

Much better is for you to use a DocumentListener or DocumentFilter, depending on if you want to listen before or after text has been fully registered with the text component.
The DocumentListener will register any time the text has changed, be it via a key press, via a copy and paste, via a deletion of text. The Timer will then wait however long you wish to do whatever action is required on the text. For example:
import java.awt.event.ActionEvent;
import java.awt.event.ActionListener;
import javax.swing.*;
import javax.swing.event.DocumentEvent;
import javax.swing.event.DocumentListener;
import javax.swing.text.BadLocationException;
import javax.swing.text.Document;
public class DocListenerFoo extends JPanel {
private JTextField nameTextField = new JTextField(20);
public DocListenerFoo() {
add(new JLabel("Add Text:"));
add(nameTextField);
int timerDelay = 1000; // one second
nameTextField.getDocument().addDocumentListener(new MyDocListener(timerDelay));
}
private class MyDocListener implements DocumentListener {
private Timer docTimer;
private int timerDelay;
public MyDocListener(int timerDelay) {
this.timerDelay = timerDelay;
}
#Override
public void changedUpdate(DocumentEvent e) {
textChangedAction(e);
}
#Override
public void insertUpdate(DocumentEvent e) {
textChangedAction(e);
}
#Override
public void removeUpdate(DocumentEvent e) {
textChangedAction(e);
}
private void textChangedAction(DocumentEvent e) {
Document doc = e.getDocument();
try {
String text = doc.getText(0, doc.getLength());
if (docTimer != null && docTimer.isRunning()) {
docTimer.stop();
}
docTimer = new Timer(timerDelay, new TimerListener(text));
docTimer.setRepeats(false);
docTimer.start();
} catch (BadLocationException e1) {
e1.printStackTrace();
}
}
}
private class TimerListener implements ActionListener {
private String text;
public TimerListener(String text) {
this.text = text;
}
#Override
public void actionPerformed(ActionEvent e) {
// TODO do check on text here
System.out.println("Checking text here: " + text);
}
}
private static void createAndShowGui() {
DocListenerFoo mainPanel = new DocListenerFoo();
JFrame frame = new JFrame("DocListenerFoo");
frame.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
frame.getContentPane().add(mainPanel);
frame.pack();
frame.setLocationByPlatform(true);
frame.setVisible(true);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}

Don't wait inside the key or document event, it just blocks the program from being processed further. Instead save the current time or (re)start a timer in the event and execute your action later somewhere else.

I'm guessing that you're trying to use a KeyListener with a Swing text component such as a JTextField (I have to guess since you don't tell or show us). If so, then the best solution is don't. Using a KeyListener with these components can mess up the functionality of the components. Much better is for you to use a DocumentListener or DocumentFilter, depending on if you want to listen before or after text has been fully registered with the text component.
For a better more complete answer, post a better more complete question, including your minimal code example and details about your problem.

Pressing both mouse buttons not working correctly

i have to check if i pressed left, right or both buttons on my mouse, here is a sample code:
package sandbox;
import java.awt.event.MouseEvent;
import java.awt.event.MouseListener;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.SwingUtilities;
public class Sandbox extends JFrame {
public static void main(String[] args) {
Sandbox s = new Sandbox();
s.setVisible(true);
}
public Sandbox() {
setDefaultCloseOperation(EXIT_ON_CLOSE);
setSize(300, 200);
setResizable(false);
setTitle("Frame");
setLayout(null);
JButton but = new JButton("click me");
but.setBounds(0, 0, 120, 50);
but.addMouseListener(new MouseListener() {
#Override
public void mouseClicked(MouseEvent e) {
}
#Override
public void mousePressed(MouseEvent e) {
if(SwingUtilities.isLeftMouseButton(e) | SwingUtilities.isRightMouseButton(e))
System.out.println("both");
else if(SwingUtilities.isLeftMouseButton(e))
System.out.println("left");
else if(SwingUtilities.isRightMouseButton(e))
System.out.println("right");
}
#Override
public void mouseReleased(MouseEvent e) {
}
#Override
public void mouseEntered(MouseEvent e) {
}
#Override
public void mouseExited(MouseEvent e) {
}
});
add(but);
}
}
i have to make it using SwingUtilities, but there is a problem if i press left or right single button it will print "both", not "left" or "right", if i used MouseEvent class it was working properly but i need it with SwingUtilities class if it's possible, thanks.
EDIT: using MouseEvent class it's working right:
if(e.getModifiersEx() == (MouseEvent.BUTTON1_DOWN_MASK | MouseEvent.BUTTON3_DOWN_MASK))
...

Don't check using OR (|) but use AND (& or better the short cut version &&) instead:
if(SwingUtilities.isLeftMouseButton(e) && SwingUtilities.isRightMouseButton(e))
...
Update:
For checking if both buttons are pressed, SwingUtilities doesn't seem to be the right tool. The isXxxxMouseButton(...) methods do the same as you do, they check the button masks, but use different masks which seem not be set when both buttons are pressed.
As an example, isRightMouseButton() is implemented as follows:
public static boolean isRightMouseButton(MouseEvent anEvent) {
return ((anEvent.getModifiers() & InputEvent.BUTTON3_MASK) == InputEvent.BUTTON3_MASK);
}
As you can see, the implementation isn't that complext, so you might be better off to just do the mask check yourself.

mouse listene event on button
but.addMouseListener(new MouseListener() {
mouse listener event on fame.
this.addMouseListener(new MouseListener() {
Please check with '||' not '|', don't use the && because it is not possible to press both buttons at the same time
if(SwingUtilities.isLeftMouseButton(e) || SwingUtilities.isRightMouseButton(e))
You will get result
both
left
both
left
both
right

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.

Java Applet Text highlights on rollover

I'm trying to figure out how to make non-editable text (not a JTextField) whose background color changes when the mouse rolls over it. I tried using JButton implementing ActionListener and hiding elements to make the button appear to be just text, but it only allows me to change icons on rollover and detect when the button is clicked. Another thought was to use MouseListener and declare the specific coordinates of a rectangle around the text, where upon mouseMoved it could initiate the highlight. But w/ that there's a problem for varying string lengths and word wrap etc. What is the best object, and listener combo to achieve the effect of a highlighted text field on mouse rollover?

Hmm maybe use a foucs listener and when the field gains foucs select all the text?
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class TextField extends JTextField {
public TextField(String text) {
super(text);
addFocusListener(new FocusAdapter() {
#Override
public void focusGained(FocusEvent fe) {
selectAll();
}
});
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
JTextField tf = new JTextField("normal field");
f.add(tf, BorderLayout.CENTER);
TextField ftf =
new TextField("funny text field");
f.add(ftf, BorderLayout.SOUTH);
f.pack();
f.setVisible(true);
}
});
}
}
EDIT:
Hmmm actually found an even better way with the above method you'd have to click on the textfield to gain focus, now i've used a thread to check when the mouse is over the components co-ordinates and then to highlight the field, I used a boolean to control the highlighting as constant highlighting throws an error. Hope this is what you want:
import java.awt.*;
import javax.swing.*;
public class TextFieldHighlight extends JTextField {
static JTextField ftf;
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
public void run() {
JFrame f = new JFrame();
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
ftf = new JTextField("Highlight");
ftf.setEditable(false);
f.add(ftf, BorderLayout.CENTER);
f.pack();
f.setVisible(true);
Thread thread = new Thread(new Runnable() {
boolean focused = false;
#Override
public void run() {
while (true) {
if (mouseIsOverDisplayPanel()) {
if (ftf.hasFocus() && focused == false) {
ftf.selectAll();
focused = true;
} else if (!ftf.hasFocus()) {
focused = false;
}
}
}
}
});
thread.start();
}
});
}
private static boolean mouseIsOverDisplayPanel() {
if (MouseInfo.getPointerInfo().getLocation().x >= ftf.getLocationOnScreen().x
&& MouseInfo.getPointerInfo().getLocation().x <= ftf.getLocationOnScreen().x + ftf.getWidth()
&& MouseInfo.getPointerInfo().getLocation().y >= ftf.getLocationOnScreen().y
&& MouseInfo.getPointerInfo().getLocation().y <= ftf.getLocationOnScreen().y + ftf.getHeight()) {
return true;
} else {
return false;
}
}
}

Removing new line function when enter button is pressed Java

I have a text area that I would like to become blank when the enter button is pressed. I know this would normally be done with a setText method. However when I do this, the text is removed but the new line function created by the return key being pressed. My question is, is the anyway of stopping this default action from happening?
thanks

Are you listening for the ENTER key on the text area and then clearing it? The following works for me:
final JTextArea ta = new JTextArea();
ta.addKeyListener(new KeyListener() {
#Override
public void keyTyped(KeyEvent e) {
}
#Override
public void keyReleased(KeyEvent e) {
if(e.getKeyCode() == KeyEvent.VK_ENTER){
ta.setText("");
}
}
#Override
public void keyPressed(KeyEvent e) {
}
});

Hi
I have a text area that I would like to become blank when the enter button is pressed.
This, I understand. Here's how you can do that:
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class Main {
public static void main(String[]args) {
final JFrame frame = new JFrame();
final JTextArea area = new JTextArea();
area.setPreferredSize(new Dimension(200, 200));
area.addKeyListener(new KeyAdapter(){
#Override
public void keyReleased(KeyEvent e) {
if(e.getKeyCode() == KeyEvent.VK_ENTER) {
area.setText("");
}
}
});
frame.add(area);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
}
I know this would normally be done with a setText method. However when I do this, the text is removed but the new line function created by the return key being pressed. My question is, is the anyway of stopping this default action from happening?
That, I don't understand.

The problem is probably that you are not consuming the keystroke event, and although the text area is cleared, the normal processing of the keystroke ends up inserting a newline.
Rather than trapping the keystroke event (which isn't necessarily portable) I would recommend using a DocumentFilter. There is a tutorial here that shows you how to write one. Implement the filter so that when there is a 'newline' in the insert or replace string, replace the entire contents of the document with "".
However this approach can't tell the difference between a newline typed at the keyboard and one pasted into the text area.

Before you clear the text you need to remove the new line code the return button left. You do that with the consume() method.
So to clear your text:
yourkeyevent.consume();
yourTextObject.setText("");

Instead, you can also use:
yourTextarea.setText(null);
yourTextarea.setCaretPosition(-1);

I solved your problem overriding the code in the method "public void keyTyped(KeyEvent e)" instead of "public void keyPressed(KeyEvent e)" and it works.
Here the code:
package versione1;
import javax.swing.*;
import java.awt.*;
import java.awt.event.*;
public class WhiteEnter {
final JFrame frame = new JFrame();
private JTextArea area = new JTextArea();
public static void main(String[]args) {
WhiteEnter prova = new WhiteEnter();
prova.run();
}
public void run(){
area.setPreferredSize(new Dimension(200, 200));
area.addKeyListener(new PressEnterKeyListener());
frame.add(area);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
public class PressEnterKeyListener implements KeyListener{
#Override
public void keyPressed(KeyEvent e) {
}
#Override
public void keyReleased(KeyEvent e) {
}
#Override
public void keyTyped(KeyEvent e) {
if (e.getKeyChar() == (KeyEvent.VK_ENTER)){
try{
area.setText(null);
area.setCaretPosition(0);
} catch(Exception ex){
ex.printStackTrace();
}
}
}
}
}