UPDATE: [[ If you're curious, refreshing the window on focus did not work well for me. They would double-click on a table in an out-of-focus window, the table would refresh on focus, and the double click event would fire against a different record than the one upon which the original click was made. ]]
Here's an example focus listener for a JInternalFrame:
package com.apexroot.sandbox;
import java.awt.Dimension;
import java.awt.EventQueue;
import java.beans.PropertyChangeEvent;
import java.beans.PropertyChangeListener;
import javax.swing.JDesktopPane;
import javax.swing.JFrame;
import javax.swing.JInternalFrame;
import javax.swing.JLabel;
/**
* author grants unlimited license to modify, reuse and redistribute. based on
* the suggestion by @mKorbel on stackoverflow at
* http://stackoverflow.com/questions/7219860/jinternalframe-selection
* please keep a URL to the original version in the source code.
* http://javajon.blogspot.com/2015/08/windowfocuslistener-for-jinternalframe.html
*
* @author Apexroot
*/
public class InternalFrameFocusListenerExample {
public static final String INTERNAL_FRAME_FOCUS_EVENT_PROPERTY = "selected";
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
final JFrame jFrame = new JFrame();
final JDesktopPane jDesktopPane = new JDesktopPane();
final JInternalFrame[] jInternalFrames = new FocusInternalFrame[3];
for (int i = 0; i < jInternalFrames.length; i++) {
jInternalFrames[i] = new FocusInternalFrame();
}
jFrame.dispose();
jFrame.setContentPane(jDesktopPane);
jDesktopPane.setPreferredSize(new Dimension(400, 200));
jFrame.pack();
jFrame.setVisible(true);
for (int i = 0; i < jInternalFrames.length; i++) {
jDesktopPane.add(jInternalFrames[i]);
jInternalFrames[i].setLocation(10 + 60 * i, 10 + 40 * i);
jInternalFrames[i].setVisible(true);
}
}
});
}
public static class FocusInternalFrame extends JInternalFrame {
public FocusInternalFrame() {
final JLabel jLabel = new JLabel("placeholder for pack();");
setContentPane(jLabel);
pack();
this.addPropertyChangeListener(
INTERNAL_FRAME_FOCUS_EVENT_PROPERTY,
new LabelFocusListener(jLabel));
}
}
private static class LabelFocusListener implements PropertyChangeListener {
private final JLabel jLabel;
public LabelFocusListener(JLabel jLabel) {
this.jLabel = jLabel;
}
@Override
public void propertyChange(PropertyChangeEvent evt) {
// please keep a URL to the original version in the source code.
// http://javajon.blogspot.com/2015/08/windowfocuslistener-for-jinternalframe.html
if (INTERNAL_FRAME_FOCUS_EVENT_PROPERTY.equals(
evt.getPropertyName())) {
final Object oldValue = evt.getOldValue();
final Object newValue = evt.getNewValue();
if (oldValue instanceof Boolean
&& newValue instanceof Boolean) {
boolean wasInFocus = (Boolean) oldValue;
boolean isInFocus = (Boolean) newValue;
if (isInFocus && !wasInFocus) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
// focus gained
jLabel.setText("focus gained");
}
});
} else if (wasInFocus && !isInFocus) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
// focus lost
jLabel.setText("focus lost");
}
});
}
}
}
}
}
}
