Using key event

hey, I have an application with multiple frames and dialogs, that are in top of each other, I would like to define a short key (Ctrl+s for example) on the top frame and to handle the event of this key combination, no matter where the focus is, it might be on other dialog... how can I accomplish this?

[Global Event Listeners|http://www.camick.com/java/blog.html?name=global-event-listeners]

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Focus problem using key event

Hi!
There is an application I've created uses key event that needs your help.
As you know, that setting 'Mnemonic' to a JButton object makes the button accessible by a key mentioned in the parameter as the following ->
               OkButton.setMnemonic(KeyEvent.VK_O);Now, pressing 'Alt' and 'O' keys together will do the same action as the 'OKButton' does.
But as of me, I think pressing two keys together is not a complete handy job.
So, is there any code that will do the same, by pressing only the 'O' key ?
Ok! I know that there is something to be taken care of; that is, if I want the button to react by pressing only the 'O' key the button must be in focus [value returned by the method [code]isFocusable() for the button must return true.]
Then how the 'Mnemonic' works ?!! When 'Mnemonic' do something, button does not have any focus.
Only, I press the Alt+O and the work done successfully! No need to take care wherever the focus is. So, is there any way to do alike, where I don't have to manage the focus subsystem?? I would only press the 'O' key and the task will be done.
Please send a sample code. Thanks!

I suggest you look into Key Bindings:
"How to Use Key Bindings"
http://java.sun.com/docs/books/tutorial/uiswing/misc/keybinding.html
Here is a short demo program that uses Key Bindings to do what you describe:
import java.awt.event.ActionEvent;
import java.awt.event.KeyEvent;
import javax.swing.*;
public class PressOTest extends JFrame {
    public PressOTest() {
        super("Press O or C");
        setDefaultCloseOperation(EXIT_ON_CLOSE);
        // Action that will be associated with the OK button and with
        // the 'O' key event
        Action okAction = new AbstractAction("Ok") {
            public void actionPerformed(ActionEvent e) {
                JOptionPane.showMessageDialog(PressOTest.this, "Ok!");
        // Action that will be associated with the Cancel button and with
        // the 'C' key event
        Action cancelAction = new AbstractAction("Cancel") {
            public void actionPerformed(ActionEvent e) {
                JOptionPane.showMessageDialog(PressOTest.this, "Cancel!");
        // Register Key Bindings for the 'O' and 'C' keys:
        InputMap im = getRootPane().getInputMap(
                JComponent.WHEN_IN_FOCUSED_WINDOW);
        ActionMap am = getRootPane().getActionMap();
        im.put(KeyStroke.getKeyStroke( KeyEvent.VK_O, 0 ), "ok");
        am.put( "ok", okAction );
        im.put(KeyStroke.getKeyStroke( KeyEvent.VK_C, 0 ), "cancel");
        am.put( "cancel", cancelAction );
        // Create and add OK & Cancel buttons:
        JButton okButton = new JButton(okAction);
        JButton cancelButton = new JButton(cancelAction);
        Box box = Box.createHorizontalBox();
        box.add( Box.createHorizontalGlue() );
        box.add( okButton );
        box.add( Box.createHorizontalStrut(10) );
        box.add( cancelButton );
        box.add( Box.createHorizontalGlue() );
        getContentPane().add( box );
        setSize(300, 300);
        setLocationRelativeTo(null);
    public static void main(String[] args) {
        new PressOTest().setVisible(true);
}

Is using key events really that hard?

I am trying to implement a keyListener for my application, and it seems
way harder than it should be. My application is simple: A JFrame
with one button and one JPanel upon which I draw. When I click
in the JPanel and type, I want things to happen.
After much looking, it seems I have to not only implement KeyListener,
but also MouseListener, so when the mouse enters I can call
requestFocusInWindow().
That seems to work sometimes, but not when I leave and come back,
and not always when the application first appears.
So do I also have to implement FocusListener?
Why is this so hard to do? MouseListener is very easy to implement,
but KeyListener seems to be a huge pain in the butt.
Can someone point me to a simple tutorial or example that just
has a few swing elements, and processes key events?
I feel like with Java I often try enough things until it finally works,
and never really understand why, and what it was that fixed it.
The documentation and API does not fully describe everything one
needs to know to use the API "properly". Am I the only one frustrated
by this? I have programmed in Java/Swing for years, and JUST LAST
WEEK discovered that when implementing paint in swing, one should
override paintComponent and not paint. But then why does overriding
paint usually work? There are too many quirks in Java that let you
get away with doing things wrong, and then suddenly, your application
is broken. It wouldn't be so bad if the API was more clear on some of
these suble issues.
Thanks,
Chuck.

How to Use Key Bindings

Hlep in deleting Componantes using Key event listeners.

Hi All,
I am tring to write a GUI program. I am dragging componets from the left side of the panel to the right side of the panel. Everything works well as of now. But i am tring to delete the componets which i placed on the right side of the paenl using key stroke events. Can anyone tell how this can be done. I have like labels and textfield componeets.
Please help
Smitha

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.Border;
public class KeyDeletion extends JPanel {
    JComponent selectedComponent;
    public KeyDeletion(JFrame f) {
        setLayout(null);
        Dimension d = new Dimension(65,25);
        for(int j = 0; j < 4; j++) {
            JLabel label = new JLabel("label " + (j+1),
                                       JLabel.CENTER);
            label.setBorder(BorderFactory.createEtchedBorder());
            int x = 20 + j*(d.width + 25);
            int y = 20 + j*(d.height + 75);
            label.setBounds(x, y, d.width, d.height);
            add(label);
        addMouseListener(ma);
        registerKey(f);
    /** Press the "x" key to delete selected label. */
    private void registerKey(JFrame f) {
        JRootPane jrp = f.getRootPane();
        int c = JComponent.WHEN_IN_FOCUSED_WINDOW;
        jrp.getInputMap(c).put(KeyStroke.getKeyStroke("X"), "DELETE");
        jrp.getActionMap().put("DELETE", deleteAction);
    public static void main(String[] args) {
        JFrame f = new JFrame();
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        KeyDeletion panel = new KeyDeletion(f);
        f.add(panel);
        f.setSize(400,400);
        f.setLocation(200,200);
        f.setVisible(true);
    private MouseAdapter ma = new MouseAdapter() {
        Border etched = BorderFactory.createEtchedBorder();
        Border select = BorderFactory.createLineBorder(Color.red);
        JComponent lastSelection;
        public void mousePressed(MouseEvent e) {
            Point p = e.getPoint();
            Component[] c = getComponents();
            boolean haveSelection = false;
            for(int j = 0; j < c.length; j++) {
                Rectangle r = c[j].getBounds();
                if(r.contains(p)) {
                    setSelection(c[j]);
                    haveSelection = true;
                    break;
            if(!haveSelection && selectedComponent != null) {
                setSelection(null);
        private void setSelection(Component c) {
            selectedComponent = (JComponent)c;
            if(c != null)
                selectedComponent.setBorder(select);
            if(lastSelection != null)
                lastSelection.setBorder(etched);
            lastSelection = selectedComponent;
    private Action deleteAction = new AbstractAction() {
        public void actionPerformed(ActionEvent e) {
            if(selectedComponent != null) {
                remove(selectedComponent);
                selectedComponent = null;
                repaint();
}

Associating key events to a TextBox

Hello All!
Can anybody tell me how to associate key events with a TextBox? Something like when a certain key is pressed and released, a certain combinations of characters is inserted e.g. =-)
I am trying to develop a simple application that allows users to type text with non-English characters, e.g. Russian and for that I have created a canvas and I am using key events i.e. KeyPressed and KeyReleased methods. Using a canvas is a bit insufficient because users cannot move the cursor freely through the text.
I have read on te web that I can create a CustomeItem and override the KeyPressed methods but I could not do it; I could not find any simlar code example.
Can anybody help me by providing me with a simple example or suggesting me an alternative way?
Many thanks in advance

{color:#008080}*Hello again!*
I managed to create a CustomItem that overrides KeyPressed method, but now I am having difficulties making my textBox reacts to my keyPressed method.
The early version of this CustomeItem overrides the KeyPressed method by assigning each key to a certain collection of chars. When a key is pressed, a string of these chars is drawn on the Canvas, which works fine. Now because I want to be able to edit the text, e.g. delete a certain char in the middle of the string, I want to use a TextBox or a TextField. The current problem is that my TextBox does not react to my key presses the way I want (I used setString() method); it reacts to the original key presses which print the original chars (from A through to Z and 1 through to 9).
Is it possible to set the contents of a TextBox or TextField depending on my key presses? Could you suggest me an alternative way?
Many thanks in advance!!{color}

How to detect the key enter with a numerical control without using loop event?

I want to accept a numerical value only when the key enter is pressed, but without using the event. How to detect the char "enter" with a numerical control?
Thanks!

When the user edits a numeric control with a keyboard, its property "key focus" is true. When the user hits enter, key focus becomes false. Poll the property to latch the control valuse at the true-false transition. That won't work if the user modify the control using up and down arrows.
LabVIEW, C'est LabVIEW

Is there a way to trigger button's action listeners from key events?

I rarely do GUI programming, especially not in Java. But now I am working on a GUI app and would like to get some help.
Say I have a simple GUI consists of a JFrame, and a bunch of buttons on its JToolBar. The buttons on the JToolBar are for navigation of a set of documents, first, prev, next, last etc. All buttons are assigned action command strings, and their all trigger the same instance of action listener. inside of the action listener, it does the correct navigation based on the action command from the event.
but some users want to be able to use the keyboard to do the navigation, because they think clicking the buttons are too slow.
So is there a graceful way to receive the different key press events and trigger corresponding navigation actions (hopefully it reuses the code that is already there, e.g. the action listener)? thanks.
-- Jim

but some users want to be able to use the keyboard to do the navigation, because they think clicking the buttons are too slow. That is always the case in any GUI. Any application should be designed to use either the mouse or the keyboard.
All buttons are assigned action command strings,That is not the way the GUI should be designed.
Instead you should be creating Actions. Then you can add the Action to a button and you can associate the Action with a KeyStroke which is called "Key Binding". This is the way all Swing components work. You can read the [url http://download.oracle.com/javase/tutorial/uiswing/TOC.html]Swing tutorial for more information and examples. Start with the section on:
a) How to Use Actions
b) How to Use Key Bindings

Detect key events on anything

If I have a JFrame with many components on it, how do I detect if a key is pressed, without having to add a listener to every component? For example, how can I check for the escape key being pressed, but not having to have componentN.addKeyListener(this); for everything?
Thanks
US101

The correct way to collect the key events is the following:
from java 1.2 to java 1.3 use the FocusManager. This class can be found in the javax.swing package. You would then need to extend the DefaultFocusManager and override specific behavior.
for java 1.4 use the KeyBoardFocusManager. This class can be found in the java.awt package.
Please see the following for a better explanation:
http://java.sun.com/j2se/1.4/docs/api/java/awt/doc-files/FocusSpec.html
Thanks for your time,
Nate

Object Movement with Key Events

Hi everybody!
Im trying to move an object over the screen with keyboard buttons. The problem I have come across with is that I would like to use the right button to move right, up button to move forward, etc. but I cant push, for example, right and up buttons at the same time to make a diagonal movement. How can I solve this?
Thank you and regards.

I added key events to a sequence and than check them in the program.
Something like this:
class Car extends CustomNode {
    var keys:KeyCode[];
    public override function create(): Node {
        ImageView {
            transforms: [ Translate{ x: bind x, y: bind y }, Rotate{ angle: bind direction}]
            x: -w
            y: -h
            image: Image { url: "{__DIR__}car.png"}
            onKeyPressed: function( e: KeyEvent ) {
                insert e.code into keys;
                if(e.code == KeyCode.VK_UP){
                    ds = 2.0;
                }else if(e.code == KeyCode.VK_DOWN){
                    ds = -2.0;
                }else if(e.code == KeyCode.VK_LEFT){
                    da = -1.0;
                }else if(e.code == KeyCode.VK_RIGHT){
                    da = 1.0;
            onKeyReleased: function( e: KeyEvent ) {
                delete e.code from keys;
    public function move(){
          // check keys
}

KEY events in MIDlets

Hello all,
I am basically new to J2ME MIDP development and also new to this
forum. So apologies if this has already been covered or turns out to
be a stupid question :) Here goes:
I am trying to develop a MIDlet where I have a Form to accept certain
values from the user. This is fairly straightforward and is easy to
create with the high level Form a and TextField objects.
Now, I wish to add a functionality to my MIDlet, in which, the user
can press a specific key.. say the "Select" key or the "Call" key.. at
any time during the form to start another thread of operation which
performs something totally different... say for example, the user is
entering values into the form and in between somewhere he presses this
specific key and the phone start playing music. I hope you get my
point.
Basically I want to listen for key pressed or key held events on a
Form object. Now I understand that Key events can be found only on the
low-level Canvas based UIs. So is it possible to do it with Screen class
elements..?
Thanks,
Nik

You can try to use a CustomItem. What events will be delivered to the custom item depends on the implementation, though. Also these events will be only delivered when the CustomItem is focused.
Have a look at the J2ME Polish GUI for using CustomItems for MIDP/1.0 devices as well.
http://www.j2mepolish.org
Best regards,
Robert

Binding Mouse and Key Events.

Hi,
When a user clicks the Ctrl + V the data from the clipboard
is pasted into the user area. Instead of using this can we do it
using a mouse click. For now, I am planning to bind the event code
of these combinations (CTRL + V == 86) to the mouse click. But when
I tried this I am unable to bind this key event to the mouse event.
Can anyone help me out for getting out of this problem.
Regards,
eodC.

No, it isn't.
Kind regards,
Levi

How to consume key events

I would like to create a subclass of TextBox that only allows numeric input. My idea was to provide my own onKeyType() handler and consume any key events that do not correspond to digits. However, I can't find any way to consume key events from further processing. How do I do this?
Are there any other suggestions how to accomplish the task of providing your own filter concerning valid key input?
/Bengt

I also wanted a kind of validators for the TextBox class of JavaFX. So I've tried solving the problem using the SwingTextField class and some Java APIs. The following is my code for a SwingTextField accepting only digits, but I do want it to be much simpler.
import java.awt.AWTEvent;
import java.awt.event.AWTEventListener;
import java.awt.event.KeyEvent;
import java.awt.Toolkit;
import javafx.ext.swing.SwingTextField;
import javafx.scene.Scene;
import javafx.stage.Stage;
import javax.swing.JComponent;
class DigitKeyEventHookListener extends AWTEventListener {
    public-init var source:JComponent;
    public override function eventDispatched( event:AWTEvent):Void {
        if (event.getSource().equals(source)) {
            var keyEvent : KeyEvent = event as KeyEvent;
            var keyCharacter = keyEvent.getKeyChar();
            var isDigit = false;
            var code = keyEvent.getKeyCode();
           if ((KeyEvent.VK_0 <= keyCharacter) and (keyCharacter <= KeyEvent.VK_9)) {
                   isDigit = true;
            if ((code ==KeyEvent.VK_DELETE) or (code ==KeyEvent.VK_BACK_SPACE)) {
                isDigit = true;
            if ((code ==KeyEvent.VK_LEFT) or (code ==KeyEvent.VK_RIGHT)) {
                isDigit = true;
           if (not isDigit) {
                keyEvent.consume();
function createSwingTextField() : SwingTextField{
    var field = SwingTextField {
        columns:12
    var listener = DigitKeyEventHookListener{
        source: field.getJTextField()
    Toolkit.getDefaultToolkit().addAWTEventListener(listener, AWTEvent.KEY_EVENT_MASK);
    return field;
Stage {
    title: "Digit Box"
    width: 200
    height: 80
    scene: Scene {
        content: createSwingTextField()
}

No key event when compose keys are pressed

I am supporting a legacy application for Sabre which maps some of the keys differently. For example, on a French keyboard the Compose key which is used to put a ^ on top of the vowel characters is to be remapped to produce a special character called a "Change Character" that has a special use for reservation agents that use Sabre
The problem is, the first time you press the ^ compose key there is no key event apparently because the VM figures it doesn't yet know what key to report, it is expecting you to press a character such as 'o' and then you get an 'o' with a '^' on top of it.
If you press the ^ compose key a second time, you get the following key events:
keyPressed
keyTyped
keyTyped
keyReleased
On the screen you will see two ^ characters appear. Currently I remap the ^ character to the "Change Character", and I suppress the second keyTyped event so that I only get one character. The problem is that the user ends up having to press the key twice to get one "Change Character."
I have no fix for this problem because there is no key event produced when they press the ^ compose key the first time.
By the way, this behavior appears to have been introduced with jdk 1.3. The older jdk did produce a key event the first time you pressed the compose key. I would expect that this behavior was considered to be a bug and was fixed in jdk 1.3.
Is there some other way to detect when the user presses a compose key? If not, is it possible for future jdk releases to report a keyPressed event when a compose key is pressed? This event would not cause a character to appear on the screen, but would allow programs to detect when the compose key is pressed.
There is already a key on the French keyboard that behaves this way. It is the key to the left of the '1' key and it has the pipe symbol on it. If you press Shift plus this pipe key, no character is produces but a keyPressed event with a keycode of 222 is produced. I merely point this out to show that there is a way to report key events whithout producing output on the screen.
Thanks, Brian Bruderer

I don't know if this actually helps, but it seems that you can bind an Action to a dead key like the circumflex of the French keyboard
Keymap keymap = textPane.addKeymap("MyEmacsBindings", textPane.getKeymap());
Action action = getActionByName(DefaultEditorKit.beginAction );
KeyStroke key = KeyStroke.getKeyStroke(KeyEvent.VK_DEAD_CIRCUMFLEX);
keymap.addActionForKeyStroke(key, action);I saw this on a Swing tutorial and modified it slightly. Have a look at it :
http://java.sun.com/docs/books/tutorial/uiswing/components/generaltext.html
Chris

Lag on key press (key event)

Hello, I am currently working on a simple game in Java. I've used Java's Key_Pressed in Key Event to control a ship moving back and forth with the up and down keys. I've noticed that when a key is pressed there is a short pause before the ship actually moves. What can I do to avoid this pause?

The "repeat rate" for holding a key down is controlled by the OS.
You should not be relying on multiple KeyEvents to move your component as the repeat rate will vary from machine to machine. Actually you should not be using KeyEvents anyway you should be using [url http://java.sun.com/docs/books/tutorial/uiswing/misc/keybinding.html]Key Bindings
On keyPressed binding you would start a Timer and then on keyReleased you stop the Timer. You can then control the interval at which the Timer fires so you game will be consistent on all machines.

Plz tell me motrola support repeated key events.

Plz tell me about my this ancient problem that if some device support repeated key event than tell me its name and also provide a link to download it.
moreover also tell me about this strange content type:-
Here i have content type which is strange for me :- response.setRequestProperty("Content-Type","application/x-www-form-urlencoded") plz tell me either it will ok if i want to display some other language;
i want internationalization and want to set utf-8 but now tell me for what purpose is above content type and what would be its alternative. thanx

See http://www.kobjects.org/devicedb/ for which devices do and don't support key repeat events.
Application/x-www-form-urlencoded is defined at
http://www.w3.org/TR/html4/interact/forms.html#h-17.13.4.1
You can use application/x-www-form-urlencoded with UTF-8 provided that the server is expecting UTF-8 encoded bytes. However, I don't think many MIDP implementations support String.getBytes("UTF-8") so you may be stuck with doing the UTF-8 encoding yourself.
If you control the server, you may want to instead use DataOutput.writeUTF() from the client and DataInput.readUTF() from the server. Another alternative is to use XML, where you can employ character references for non-US-ASCII characters.

Using key event

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