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

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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);
}

Sync one folder two machines - Is it really that hard.

Sync one folder two machines - Is it really that hard.
I have one folder (with a bunch of subfolders totally 3k of image files) I'd like to mirror them on both my laptop and desktop machines.
I'd like the Desktop machine to mirror everything on the laptop and when I travel with the laptop I add images once I return everything new will be copied over.
Things I don't want in this system
• Third party software, If the OSX 10.4.8 can do it all the better
• Having to Manually hit a sync button. (But willing to budge on this one)
• It Making a duplicate copy of the folder each and everytime it connects.
I have looked at a few free items on mac's website:
Auto-backup Script (written in 2000)
http://www.apple.com/applescript/folderactions/05.html
Sync Folders 0.9 (written in 2004)
http://www.apple.com/downloads/macosx/automator/syncfolders.html
But I can't seem to get either to work on my machines The script is asking me to do something that I can't even phyically do anymore in 10.4.8
any idea's or suggestions?
Thanks
Robert Dall
iMac G4, iBook G4 Mac OS X (10.4.8) 80g video ipod (black is back baby!)

So much for other people having lives to live...
I'd help you out if I knew anything about rsync, and
I'm sure many others would, too, but apparently the
ones who do know are doing other things. Considering
it's a weekend, that really shouldn't be surprising.
There are people and companies that give such
immediate service for a fee. Look around and I'm sure
you'll find one that'll offer to not only advise you
but will also create the solution for you. They'll
even you let you have the solution, for a price.
Azqi, please don't belittle me about how the captitalism works in the world. I might been in a small community outside Vancouver that doesn't even have a large MAC dealership who could answer my question. I was already at the shop that does deal in mac because I wanted to SHOP LOCAL. I am perfectly aware I am on a FREE forum and have a life outside of this forum also! I waited four days before I said what I said and before my little question was lost in the forums. If I had 300 responses to my question like yours I'd never return. . . .
I am just saying that it has been a bit of a cold welcome to these forums, as this isn't the first question that has gone unanswered. . . . and thanks to some helpful folks it isn't.

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();
}

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]

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 distinguish is cell get key event or mouse event in table?

Hi!
I have a JTable.
1.Select cell and double click. As result caret is show
2.Select cell and start type. As result caret is show
How distinguish is caret is show, because cell get mouse event or key event?
Thank you.

Hm ...
the problem with the key events is, that they are partically taking place in an editor component - but the double click of the mouse clicked on a cell, which is not currently edited, can be get by a MouseListener added to the JTable.
My idea to that is as follows - hold the double_clicked state in a boolean variable hold by your JTable subclass - it is set by a MouseListener added to the JTable - and reset by the overwritten prepareEditor(...) method. This method should do the following:
// say, double_clicked is a boolean field in your JTable subclass
public Component prepareEditor(TableCellEditor editor,int row,int column) {
Component c = super.prepareEditor(editor,row,column);
if ((!double_clicked)&&(c instanceof JTextField)) { ((JTextField) c).setText(""); }
double_clicked = false;
return c;
}now you have only to implement an add a MouseListener to your JTable subclass which detects this double click and sets the double_clicked field accordingly.
This is an idea on the fly - hope it is helpful for you.
greetings Marsian

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

Trying to use a new, larger external hard drive for my Time Machine backup. However, every time I start the backup, it gets started then fails. And, I can't delete the few files that did save on the external. Sort of a catch 22. Any ideas?

Trying to use a new, larger external hard drive for my Time Machine backup. However, every time I start the backup, it gets started then fails. And, I can't delete the few files that did save on the external. Sort of a catch 22. Any ideas?

Is it a USB hard drive? USB hard drives have the problem of not giving full speed if they are hooked up on the same bus as keyboards and mice. Double check your profiler to make sure that is not a problem. If it is Firewire, make sure there aren't other firewire devices in use at the same time. I recommend not only keeping a Time Machine backup, but also a clone, and if you do use Time Machine, to make sure the Time Machine drive or partition is at least twice the size of the original drive.

How to use an Event Structure responding to an image control that belongs to a parent VI.

Hi
I am loading a subpanel vi by pressing a button located in the user interface of the main vi which also contains an image display. Subpanel vi opens up on the side and doesn't hide the image display of the main vi. Subpanel vi contains an event structure that needs to respond to user clicking on the image display of main vi.
Since the bug that occured while creating an image reference control isn't fixed, I am passing the main vi pane reference onto the subpanel vi. From that point I've tried to edit event structure and have it respond to the image control/pane that belongs to main vi but I don't know how.
Any help would be appreciated.
Thanks

Post a screenshot of your subVI code where you register the events.
André
Regards,
André
Using whatever version of LV the customer requires. (LV5.1-LV2012) (www.carya.nl)

On my Macbook pro 15 2011, System Profiler is suggesting that it uses SATA III for the hard drive and SATA II for the Optical Drive. Is that true?

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That is correct. The tech specs indicate:
Hard Drive Interface
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Optical Drive Interface
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I need to back up my imac running Tiger (no time machine) so that we can upgrade OS. It is set up for multiple accounts. How do I capture all files in each account using newly purchased USB external hard drive?

I need to back up my imac running Tiger (no time machine) so that we can upgrade OS. It is set up for multiple accounts. How do I capture all files in each account using newly purchased USB external hard drive? Thanks!

Backup Software Recommendations
Carbon Copy Cloner
Data Backup
Deja Vu
SuperDuper!
Synk Pro
Tri-Backup
Others may be found at VersionTracker or MacUpdate.
Visit The XLab FAQs and read the FAQ on backup and restore. Also read How to Back Up and Restore Your Files.
Or you can simply use the Restore option of Disk Utility to clone the drive to the backup:
Clone using Restore Option of Disk Utility
Open Disk Utility from the Utilities folder.
Select the destination volume from the left side list.
Click on the Restore tab in the DU main window.
Check the box labeled Erase destination.
Select the destination volume from the left side list and drag it to the Destination entry field.
Select the source volume from the left side list and drag it to the Source entry field.
Double-check you got it right, then click on the Restore button.
Destination means the external backup drive. Source means the internal startup drive.

What are main events in that are used in ALV reports

hi gurus
what are main events in that are used in ALV reports....
regards
baskar

hi
i think this will help u.
Events in alv and their FM    The main events in alv and their FM and why we use these:
1. SLIS_PRINT_ALV.
2. SLIS_T_LISTHEADER.
3. SLIS_T_EVENT.
4. SLIS_T_SORTINFO_ALV.
5. SLIS_T_LAYOUT_ALV.
6. SLIS_T_FIELDCAT_ALV.
and in classic reports what is the sequence of events:   === Events are
At selection-screen output.
Initialization.
At selection-screen on field
At selection-screen on end of field
At selection-screen on Radiobutton Group R1. (If you have any radio buttons)
At selection-screen on block b1. (If you have any blocks)
Start-of-selection.
Get node. (if the data is retreived from a logical database)
Get node late. (if the data is retreived from a logical database)
Top-of-page. (if the write statement is in the end-of-selection event or we can say that before the first write statement)
end-of-selection.
and fuction modules are
LISTHEADER - Is used to print the header information in the ALV List. Name, Date, Time, ALV Name and other details are called as Header information.   EVENT - Basically this is the FM to handle Event's. When the user needs to do some event operation like when double clicking the a particular field we need to perform some operation.   These events are captured by this FM.   LAYOUT - This FM is used to define the layout of the List. There are many options available in this FM to define the Layout style.   FIELDCAT - These are used to populate the List header. We can change them according to our req.
User-defined Text Output Event
    Application
      print_end_of_list
    Define output text to be printed at the end of the entire list
      print_top_of_list
    Define output text to be printed at the beginning of the entire list
      print_end_of_page
    Define output text to be printed at the end of each page
      print_top_of_page
    Define output text to be printed at the beginning of each page
      subtotal_text
    Define self-defined subtotals texts
Mouse-controlled Actions in the Grid Control Event
    Application
      button_click
    Query a click on a pushbutton in the ALV Grid Control
      double_click
    Query a double-click on a cell of the ALV Grid control
      hotspot_click
    Query a hotspot click on columns defined for this purpose in advance
      onDrag
    Collect information when elements of the ALV Grid Control are dragged
      onDrop
    Process information when elements of the ALV Grid Control are dropped
      onDropComplete
    Perform final actions after successful Drag&Drop
      onDropGetFlavor
    Distinguish between options for Drag&Drop behavior
Processing of Self-defined and Standard Functions Event
    Application
      before_user_command
    Query self-defined and standard function codes
      user_command
    Query self-defined function codes
      after_user_command
    Query self-defined and standard function codes
Definition of Self-defined Functions Event
    Application
      toolbar
    Change, delete or add GUI elements in the toolbar
      menu_button
    Define menus for menu buttons in the toolbar
      context_menu_request
    Change context menu
      onf1
    Define self-defined F1 help
All of these can be found under type group SLIS.
Events
SLIS_EV_ITEM_DATA_EXPAND        TYPE SLIS_FORMNAME VALUE 'ITEM_DATA_EXPAND',
SLIS_EV_REPREP_SEL_MODIFY       TYPE SLIS_FORMNAME VALUE 'REPREP_SEL_MODIFY', SLIS_EV_CALLER_EXIT_AT_START TYPE SLIS_FORMNAME VALUE 'CALLER_EXIT',
SLIS_EV_USER_COMMAND              TYPE SLIS_FORMNAME VALUE 'USER_COMMAND',
SLIS_EV_TOP_OF_PAGE                     TYPE SLIS_FORMNAME VALUE 'TOP_OF_PAGE',
SLIS_EV_DATA_CHANGED                TYPE SLIS_FORMNAME VALUE 'DATA_CHANGED',
SLIS_EV_TOP_OF_COVERPAGE       TYPE SLIS_FORMNAME VALUE 'TOP_OF_COVERPAGE',
SLIS_EV_END_OF_COVERPAGE       TYPE SLIS_FORMNAME VALUE 'END_OF_COVERPAGE',
SLIS_EV_FOREIGN_TOP_OF_PAGE TYPE SLIS_FORMNAME
VALUE 'FOREIGN_TOP_OF_PAGE', SLIS_EV_FOREIGN_END_OF_PAGE TYPE SLIS_FORMNAME
VALUE 'FOREIGN_END_OF_PAGE',
SLIS_EV_PF_STATUS_SET                  TYPE SLIS_FORMNAME VALUE 'PF_STATUS_SET',
SLIS_EV_LIST_MODIFY                      TYPE SLIS_FORMNAME VALUE 'LIST_MODIFY',
SLIS_EV_TOP_OF_LIST                       TYPE SLIS_FORMNAME VALUE 'TOP_OF_LIST',
SLIS_EV_END_OF_PAGE                    TYPE SLIS_FORMNAME VALUE 'END_OF_PAGE',
SLIS_EV_END_OF_LIST                      TYPE SLIS_FORMNAME VALUE 'END_OF_LIST',
SLIS_EV_AFTER_LINE_OUTPUT       TYPE SLIS_FORMNAME VALUE 'AFTER_LINE_OUTPUT', SLIS_EV_BEFORE_LINE_OUTPUT     TYPE SLIS_FORMNAME VALUE 'BEFORE_LINE_OUTPUT',
SLIS_EV_SUBTOTAL_TEXT                TYPE SLIS_FORMNAME VALUE 'SUBTOTAL_TEXT'.
with regards
sravani
award points if found useful.

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Is using key events really that hard?

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