Develop Reference

Java Swing - Show glasspane and consume events without losing previous focus owner

We are trying to show the user a milky JGlassPane to indicate that events are currently not accepted, due to a progress-bar or something else currently being shown. While this would usually automatically work, since we are showing a modal dialog, we also want the JGlassPane to be usable without a JDialog, meaning just a JGlassPane and a waiting cursor.
So far, we did this by using a JGlassPane that ignores events and paints a translucent color. Initially we call requestFocus on the JGlassPane. The problem with this is, that we lose the previously focused components when the glasspane goes away. The solution for this was to simply remember the previously focused component. However, in cases where the Action, that triggered the JGlassPane, was invoked via a menu, the focused component was the windows JRootPane. Usually swing correctly restores the focus after closing a menu, however, in this case, we are breaking this functionallity. Is there a way to achieve what we want without breaking the focus behaviour?
In this demo you can see, that the focus is correctly returned when hitting ESC after using one of the two buttons, but not with the context menu on the table.
public class FocusDemo
{
//Temporary static veriable for demo purposes.
private static final AtomicReference<Component> previouslyFocused = new AtomicReference<>();
private static class ConsumingGlassPane extends JPanel
{
public ConsumingGlassPane()
{
setOpaque( false );
setFocusable( true );
addMouseListener( new MouseListener()
{
#Override
public void mouseClicked( #NonNull final MouseEvent e )
{
e.consume();
}
#Override
public void mousePressed( #NonNull final MouseEvent e )
{
e.consume();
}
#Override
public void mouseReleased( #NonNull final MouseEvent e )
{
e.consume();
}
#Override
public void mouseEntered( #NonNull final MouseEvent e )
{
e.consume();
}
#Override
public void mouseExited( #NonNull final MouseEvent e )
{
e.consume();
}
} );
addKeyListener( new KeyListener()
{
#Override
public void keyTyped( final KeyEvent e )
{
e.consume();
}
#Override
public void keyReleased( final KeyEvent e )
{
e.consume();
}
#Override
public void keyPressed( final KeyEvent e )
{
if ( e.getKeyCode() == KeyEvent.VK_ESCAPE )
{
setVisible( false );
final Component component = previouslyFocused.get();
if ( component != null )
{
component.requestFocusInWindow();
}
}
e.consume();
}
} );
// This component keeps the focus until is made hidden
setInputVerifier( new InputVerifier()
{
#Override
public boolean verify( final JComponent input )
{
return !isVisible();
}
} );
}
#Override
protected void paintComponent( final Graphics g )
{
final Graphics2D g2 = (Graphics2D) g.create();
g2.setColor( new Color( 240, 230, 230, 128 ) );
g2.fillRect( 0, 0, getWidth(), getHeight() );
g2.dispose();
}
}
public static void main( final String[] args )
{
final JFrame frame = new JFrame();
frame.setGlassPane( new ConsumingGlassPane() );
final ActionListener showglasspane = __ ->
{
previouslyFocused.set( frame.getFocusOwner() );
frame.getRootPane().getGlassPane().setVisible( true );
frame.getRootPane().getGlassPane().requestFocus();
};
final JButton button1 = new JButton( "Show GlassPane" );
final JButton button2 = new JButton( "Show GlassPane" );
button1.addActionListener( showglasspane );
button2.addActionListener( showglasspane );
final Object[][] objects = { { 1, 2, 3 }, { 1, 2, 3 } };
final String[] col = { "Lel", "Lol", "Lul" };
final JTable table = new JTable( objects, col );
final JMenuItem menuItem = new JMenuItem( "Show GlassPane" );
menuItem.addActionListener( showglasspane );
final JPopupMenu popup = new JPopupMenu();
popup.add( menuItem );
table.setComponentPopupMenu( popup );
frame.setLayout( new GridBagLayout() );
frame.add( button1 );
frame.add( button2 );
frame.add( table );
frame.setDefaultCloseOperation( WindowConstants.EXIT_ON_CLOSE );
frame.pack();
frame.setLocationRelativeTo( null );
frame.setVisible( true );
}
}

How to use gettext and settext

So I have 2 different panels, the first panel works like it should but the Actionlistener might be needed to solve my issue:
class knopHandler implements ActionListener
{
public void actionPerformed ( ActionEvent e )
{
JFrame frame2 = new JFrame ( "Total Hours" );
frame2.setSize ( 600, 500 );
JPanel uitvoerpanel = new uitvoerpanel();
frame2.setContentPane( uitvoerpanel );
frame2.setVisible( true );
frame1.setVisible( false );
String invoerstring1 = maandaginvoer.getText();
int getal1 = Integer.parseInt( invoerstring1 );
String invoerstring2 = dinsdaginvoer.getText();
int getal2 = Integer.parseInt( invoerstring2 );
String invoerstring3 = woensdaginvoer.getText();
int getal3 = Integer.parseInt( invoerstring3 );
String invoerstring4 = donderdaginvoer.getText();
int getal4 = Integer.parseInt( invoerstring4 );
String invoerstring5 = vrijdaginvoer.getText();
int getal5 = Integer.parseInt( invoerstring5 );
String invoerstring6 = zaterdaginvoer.getText();
int getal6 = Integer.parseInt( invoerstring6 );
String invoerstring7 = zondaginvoer.getText();
int getal7 = Integer.parseInt( invoerstring7 );
int resultaat = getal1 + getal2 + getal3 + getal4 + getal5 + getal6 + getal7;
}
}
The relevant part of the second panel looks like this :
public uitvoerpanel()
{
setLayout( null );
naamvak = new JTextField ( 20 );
naamvak.setHorizontalAlignment ( JTextField.LEFT );
naamvak.setEditable ( false );
naamvak.setText( naaminvoer.getText() );
badgevak = new JTextField ( 20 );
badgevak.setHorizontalAlignment ( JTextField.LEFT );
badgevak.setEditable ( false );
badgevak.setText( badgeinvoer.getText() ) ;
totaalurenvak = new JTextField ( 20 );
totaalurenvak.setHorizontalAlignment ( JTextField.LEFT );
totaalurenvak.setEditable ( false );
totaalurenvak.setText( "" + resultaat );
The first panel has a few textfields where people can type something, I want the text from those textfields to appear in the textfields in the second panel but I am at a loss. When I run the program now nothing appears in the textfields in the second panel.
The "int resultaat" from the actionlistener should also appear in one of the textfields but I have also not been able to get this to work.
Am I putting the setter/getter in the right place or should this be in the actionlistener for example? Or am I missing a different piece of code?

Say, your button is jButton1 and your textFields are jTextField1 and jTextField2
Add an actionListner for your button as:
jButton1.addActionListener(new java.awt.event.ActionListener() {
public void actionPerformed(java.awt.event.ActionEvent evt) {
jButton1ActionPerformed(evt);
}
});
Then simply implement this method:
private void jButton1ActionPerformed(java.awt.event.ActionEvent evt) {
String s=jTextField1.getText();
jTextField2.setText(s);
}

Event handling with Action Listeners in Swing is straightforward.
As mentioned in the docs, you need to perform the following steps:
Declare an event handler class and specify that the class either
implements an ActionListener interface or extends a class that
implements an ActionListener interface. For example:
public class MyClass implements ActionListener {
Register an instance of the event
handler class as a listener on one or more components. For example:
someComponent.addActionListener(instanceOfMyClass);
Include code that
implements the methods in listener interface. For example:
public void actionPerformed(ActionEvent e) {
...//code that reacts to the action... }
I see that you are already trying to do some of these.
The problem in your method is that you cannot have an action listener on a panel which is a container of components. You need to define your action listener for individual components e.g. in your case, the text field maandaginvoer. You need to register (step 2) your listener with the text field on the panel 1.
Once you fix this problem, you should be able to see your desired output.

How can I find out which keys are pressed without a listener? [duplicate]

I'm creating a form in Java Swing, and one of the fields is a JTextArea. When I use the Tab key on all other fields, it gives the focus to the next widget, but in the JTextArea, it inserts a tab character (horizontal space) in the text.
How can I modify this behavior?

/*
This is my understanding of how tabbing works. The focus manager
recognizes the following default KeyStrokes for tabbing:
forwards: TAB or Ctrl-TAB
backwards: Shift-TAB or Ctrl-Shift-TAB
In the case of JTextArea, TAB and Shift-TAB have been removed from
the defaults which means the KeyStroke is passed to the text area.
The TAB KeyStroke inserts a tab into the Document. Shift-TAB seems
to be ignored.
This example shows different approaches for tabbing out of a JTextArea
Also, a text area is typically added to a scroll pane. So when
tabbing forward the vertical scroll bar would get focus by default.
Each approach shows how to prevent the scrollbar from getting focus.
*/
import java.awt.*;
import java.util.*;
import java.awt.event.*;
import javax.swing.*;
public class TextAreaTab extends JFrame
{
public TextAreaTab()
{
Container contentPane = getContentPane();
contentPane.setLayout(new BoxLayout(contentPane, BoxLayout.Y_AXIS));
contentPane.add( nullTraversalKeys() );
contentPane.add( writeYourOwnAction() );
contentPane.add( useKeyListener() );
contentPane.add( addTraversalKeys() );
}
// Reset the text area to use the default tab keys.
// This is probably the best solution.
private JComponent nullTraversalKeys()
{
JTextArea textArea = new JTextArea(3, 30);
textArea.setText("Null Traversal Keys\n2\n3\n4\n5\n6\n7\n8\n9");
JScrollPane scrollPane = new JScrollPane( textArea );
// scrollPane.getVerticalScrollBar().setFocusable(false);
textArea.setFocusTraversalKeys(KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, null);
textArea.setFocusTraversalKeys(KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, null);
return scrollPane;
}
// Replace the Tab Actions. A little more complicated but this is the
// only solution that will place focus on the component, not the
// vertical scroll bar, when tabbing backwards (unless of course you
// have manually prevented the scroll bar from getting focus).
private JComponent writeYourOwnAction()
{
JTextArea textArea = new JTextArea(3, 30);
textArea.setText("Write Your Own Tab Actions\n2\n3\n4\n5\n6\n7\n8\n9");
JScrollPane scrollPane = new JScrollPane( textArea );
InputMap im = textArea.getInputMap();
KeyStroke tab = KeyStroke.getKeyStroke("TAB");
textArea.getActionMap().put(im.get(tab), new TabAction(true));
KeyStroke shiftTab = KeyStroke.getKeyStroke("shift TAB");
im.put(shiftTab, shiftTab);
textArea.getActionMap().put(im.get(shiftTab), new TabAction(false));
return scrollPane;
}
// Use a KeyListener
private JComponent useKeyListener()
{
JTextArea textArea = new JTextArea(3, 30);
textArea.setText("Use Key Listener\n2\n3\n4\n5\n6\n7\n8\n9");
JScrollPane scrollPane = new JScrollPane( textArea );
scrollPane.getVerticalScrollBar().setFocusable(false);
textArea.addKeyListener(new KeyAdapter()
{
public void keyPressed(KeyEvent e)
{
if (e.getKeyCode() == KeyEvent.VK_TAB)
{
e.consume();
KeyboardFocusManager.
getCurrentKeyboardFocusManager().focusNextComponent();
}
if (e.getKeyCode() == KeyEvent.VK_TAB
&& e.isShiftDown())
{
e.consume();
KeyboardFocusManager.
getCurrentKeyboardFocusManager().focusPreviousComponent();
}
}
});
return scrollPane;
}
// Add Tab and Shift-Tab KeyStrokes back as focus traversal keys.
// Seems more complicated then just using null, but at least
// it shows how to add a KeyStroke as a focus traversal key.
private JComponent addTraversalKeys()
{
JTextArea textArea = new JTextArea(3, 30);
textArea.setText("Add Traversal Keys\n2\n3\n4\n5\n6\n7\n8\n9");
JScrollPane scrollPane = new JScrollPane( textArea );
scrollPane.getVerticalScrollBar().setFocusable(false);
Set set = new HashSet( textArea.getFocusTraversalKeys(
KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS ) );
set.add( KeyStroke.getKeyStroke( "TAB" ) );
textArea.setFocusTraversalKeys(
KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS, set );
set = new HashSet( textArea.getFocusTraversalKeys(
KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS ) );
set.add( KeyStroke.getKeyStroke( "shift TAB" ) );
textArea.setFocusTraversalKeys(
KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS, set );
return scrollPane;
}
class TabAction extends AbstractAction
{
private boolean forward;
public TabAction(boolean forward)
{
this.forward = forward;
}
public void actionPerformed(ActionEvent e)
{
if (forward)
tabForward();
else
tabBackward();
}
private void tabForward()
{
final KeyboardFocusManager manager =
KeyboardFocusManager.getCurrentKeyboardFocusManager();
manager.focusNextComponent();
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
if (manager.getFocusOwner() instanceof JScrollBar)
manager.focusNextComponent();
}
});
}
private void tabBackward()
{
final KeyboardFocusManager manager =
KeyboardFocusManager.getCurrentKeyboardFocusManager();
manager.focusPreviousComponent();
SwingUtilities.invokeLater(new Runnable()
{
public void run()
{
if (manager.getFocusOwner() instanceof JScrollBar)
manager.focusPreviousComponent();
}
});
}
}
public static void main(String[] args)
{
TextAreaTab frame = new TextAreaTab();
frame.setDefaultCloseOperation( EXIT_ON_CLOSE );
frame.pack();
frame.setLocationRelativeTo(null);
frame.setVisible(true);
}
}

you could use the "NextWidget.grabFocus()" method within keylistener of JTextArea when key "tab" is pressed
With this latter approach the tab character will still get inserted into the JTextArea before the focus is shifted away. If you dont want that behavior you can create a subclass of JTextArea whose isManagingFocus() method always returns false, instead of true. For example:
import javax.swing.*;
public class NoTabTextArea extends JTextArea {
public boolean isManagingFocus() {
return false;
}
}
An instance of NoTabTextArea can be used exactly like a JTextArea, except that the tab key will cause the focus to shift away from it without a tab character being inserted.

You can call the following method in your main JFrame or JPanel constructor.
Use by calling as so: disableTabbingInTextAreas(this)
public static void disableTabbingInTextAreas(Component component){
if(component instanceof Container && !(component instanceof JTextArea)){
for(final Component c : ((Container) component).getComponents() ){
disableTabbingInTextAreas(c);
}
}else if(component instanceof JTextArea){
final Component c = component;
c.addKeyListener(new KeyListener() {
#Override
public void keyTyped(KeyEvent e) {}
#Override
public void keyPressed(KeyEvent e) {
if(e.getKeyChar() == '\t'){
c.transferFocus();
e.consume();
}
}
#Override
public void keyReleased(KeyEvent e) {}
});
}
}

import javax.swing.* ;
import java.awt.event.* ;
/**
* This simple subclass of JTextArea does not allow the 'Tab'
* to be pressed. Instead of putting in 3 blank spaces, the tab
* will transfer focus
*/
/*-----------------------------------------------------------*/
/* */
/* NoTabJTextArea */
/* */
/*-----------------------------------------------------------*/
public class NoTabJTextArea extends JTextArea implements KeyListener {
public NoTabJTextArea ( String text ) {
super ( text ) ;
initialize () ;
}
public NoTabJTextArea ( ) {
super() ;
initialize() ;
}
public NoTabJTextArea ( MaskDocument document ) {
super ( document ) ;
initialize() ;
}
private void initialize () {
addKeyListener ( this ) ;
}
public void keyPressed ( KeyEvent e ) {
switch ( e.getKeyCode() ) {
case KeyEvent.VK_TAB :
e.consume() ;
transferFocus() ;
break ;
}
}
public void keyReleased ( KeyEvent e ) {
switch ( e.getKeyCode() ) {
case KeyEvent.VK_TAB :
System.out.println ( "KEY RELEASED TAB" ) ;
break ;
}
}
public void keyTyped ( KeyEvent e ) {
switch ( e.getKeyCode() ) {
case KeyEvent.VK_TAB :
System.out.println ( "KEY TYPED TAB" ) ;
break ;
}
}
} /* NoTabJTextArea */

As isManagingFocus method is deprecated since 1.4, it is also possible to use setFocusTraversalKeys. The example applies the default "on tab" behaviour to the JTextArea field.
import javax.swing.*;
import java.awt.*;
public class NoTabTextArea extends JTextArea {
public NoTabTextArea(String text, int rows, int columns) {
super(text, rows, columns);
setFocusTraversalKeys(KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS,
KeyboardFocusManager.getCurrentKeyboardFocusManager()
.getDefaultFocusTraversalKeys(KeyboardFocusManager.FORWARD_TRAVERSAL_KEYS));
setFocusTraversalKeys(KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS,
KeyboardFocusManager.getCurrentKeyboardFocusManager()
.getDefaultFocusTraversalKeys(KeyboardFocusManager.BACKWARD_TRAVERSAL_KEYS));
}
}

Trying to update my JFrame, why won't repaint work?

I will run the program, but when I activate the event, the JFrame will not update (it only removes the JLabel ) unless I manually drag the window to resize it, even with the repaint() being called after the event takes place. What's wrong?
public Driver() {
setLayout( new FlowLayout() );
pass = new JPasswordField( 4 );
add( pass );
image = new ImageIcon( "closedD.png" );
label = new JLabel( "Enter the password to enter the journal of dreams" , image , JLabel.LEFT );
add( label );
button = new JButton( "Enter" );
add( button );
event e = new event();
button.addActionListener( e );
setDefaultCloseOperation( JFrame.EXIT_ON_CLOSE );
setVisible( true );
setSize( 1600/2 , 900/2 );
setTitle( "Diary" );
}
//main method
//
//
public static void main( String[] args ) {
win = new Driver();
}
public class event implements ActionListener {
private boolean clickAgain = false;
public void actionPerformed( ActionEvent e ) {
if ( passEquals( password ) && clickAgain == false ) {
image2 = new ImageIcon( "openD.png" );
remove( label );
label = new JLabel( "Good Job! Here is the journal of dreams." , image2 , JLabel.LEFT );
add( label );
clickAgain = true;
}
repaint();
}
}

Any time you add or remove a component, you must tell its container to re-layout the current components it holds. You do this by calling revalidate() on it. You would then call repaint() after the revalidate call to have the container repaint itself.
public void actionPerformed( ActionEvent e ) {
if ( passEquals( password ) && clickAgain == false ) {
image2 = new ImageIcon( "openD.png" );
remove( label );
label = new JLabel( "Good Job! Here is the journal of dreams.",
image2 , JLabel.LEFT );
add( label );
clickAgain = true;
}
revalidate(); // **** added ****
repaint();
}
Note: your question is worded in such a way as if you assume that we know what you're trying to do. Please give us more information next time. The better and more informative the question, the better and more informative the answer.
Edit 2:
I wonder if you could simplify your code a bit. Instead of removing and adding a JLabel, better to just simply set the current JLabel's text and Icon:
public void actionPerformed( ActionEvent e ) {
if ( passEquals( password ) && clickAgain == false ) {
image2 = new ImageIcon( "openD.png" );
// remove( label ); // removed
label.setText( "Good Job! Here is the journal of dreams.");
label.setIcon(image2);
}
}

Java Swing - Flashing icon not showing up

I am trying to flash the icon to the user using a GlassPane. I am running a javax.swing.Timer which basically performs this:
for (int i = 0; i < 3; i++) {
frame.getGlassPane().setVisible(true);
try {
Thread.sleep(500);
} catch (InterruptedException e1) {
//To change body of catch statement use File | Settings | File Templates.
e1.printStackTrace();
}
frame.getGlassPane().setVisible(false);
}
Unfortunatly, if I sleep the EDT (current thread within the timer), the icon does not show, as in the paintComponent method did not manage to get invoked fully before the thread went to sleep. Therefore, when the next instruction kicks in, the glass pane is hidden, and, as a result, the icon is never shown. Is there a way to achieve what I want using this (similiar) approach?

You could use a javax.swing.Timer
public FlashTimer() {
javax.swing.Timer flashTimer = new javax.swing.Timer(500, new FlashHandler());
flashTimer.setCoalesce(true);
flashTimer.setRepeats(true);
flashTimer.setInitialDelay(0);
}
public class FlashHandler implements ActionListener {
private int counter;
#Override
public void actionPerformed(ActionEvent ae) {
countrol.setVisible(counter % 2 == 0);
counter++;
if (counter > 3) {
((Timer)ae.getSource()).stop();
}
}
}

It should be obvious - use a separate Thread and do the "blinking logic" there but modify the UI in EDT. Here is a simple example (should be enough to understand the idea):
public static void main ( String[] args )
{
JFrame frame = new JFrame ();
final JLabel label = new JLabel ( "X" );
label.setBorder ( BorderFactory.createEmptyBorder ( 90, 90, 90, 90 ) );
frame.add ( label );
frame.setDefaultCloseOperation ( JFrame.EXIT_ON_CLOSE );
frame.pack ();
frame.setLocationRelativeTo ( null );
frame.setVisible ( true );
new Thread ( new Runnable ()
{
public void run ()
{
for ( int i = 0; i < 15; i++ )
{
try
{
setVisible ( false );
Thread.sleep ( 500 );
setVisible ( true );
Thread.sleep ( 500 );
}
catch ( InterruptedException e1 )
{
//
}
}
}
private void setVisible ( final boolean visible )
{
SwingUtilities.invokeLater ( new Runnable ()
{
public void run ()
{
label.setVisible ( visible );
}
} );
}
} ).start ();
}