I'm using GroupLayout
to manage components in some dynamically generated data input forms. The layout is more or less like so:
*-----------------------------------------------*
| label A | field A |
| label B | field B |
| label C | field C |
*-----------------------------------------------*
I'm using 2 parallel groups for the horizontal layout, and a single sequential group for the vertical layout. For the most part, everything is working just fine.
I want to limit the maximum width of the labels (which are just instances of JLabel
) to 1/3 of the width of the parent JFrame
. If the JFrame
was a fixed size this would be trivial, but I have to deal with it being resized.
I'm picking up ComponentListener.componentResized()
events from the JFrame
but I'm a bit stuck on what to do once I receive such an event.
I've tried this approach without any luck:
public void componentResized(ComponentEvent e) {
int maxW = parentFrame.getWidth() / 3;
for (JLabel l : labels) {
l.setMaximumSize( // have also tried setSize() and setPreferredSize()
new Dimension(
Math.min(l.getSize().width, maxW),
l.getMaximumSize().height));
}
groupLayout.invalidateLayout(getContentSpace());
}
Can anyone suggest a way to limit the width of the labels which will work?
I could probably rebuild the layout from scratch every time, but I feel like there ought to be a simpler way.
In this example, GroupLayout
can simply rely on the preferred size of the label, without having to resort to any setXXXSize()
method. In this approach,
The use of GroupLayout.Alignment.TRAILING
to right justify the labels is a personal preference, and I've added a second panel to show how it works nested in another layout.
import java.awt.EventQueue;
import javax.swing.BorderFactory;
import javax.swing.Box;
import javax.swing.BoxLayout;
import javax.swing.GroupLayout;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JTextField;
/** @see http://stackoverflow.com/questions/8492065 */
public class GroupPanel extends JPanel {
private JLabel label1 = new JLabel("Primary:");
private JTextField field1 = new JTextField(16);
private JLabel label2 = new JLabel("Secondary:");
private JTextField field2 = new JTextField(16);
private JLabel label3 = new JLabel("Tertiary:");
private JTextField field3 = new JTextField(16);
public GroupPanel(int n) {
this.setBorder(BorderFactory.createTitledBorder("Panel " + n));
GroupLayout layout = new GroupLayout(this);
this.setLayout(layout);
layout.setAutoCreateGaps(true);
layout.setAutoCreateContainerGaps(true);
layout.setHorizontalGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(GroupLayout.Alignment.TRAILING)
.addComponent(label1)
.addComponent(label2)
.addComponent(label3))
.addGroup(layout.createParallelGroup(GroupLayout.Alignment.LEADING)
.addComponent(field1)
.addComponent(field2)
.addComponent(field3))
);
layout.setVerticalGroup(layout.createSequentialGroup()
.addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
.addComponent(label1)
.addComponent(field1))
.addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
.addComponent(label2)
.addComponent(field2))
.addGroup(layout.createParallelGroup(GroupLayout.Alignment.BASELINE)
.addComponent(label3)
.addComponent(field3))
);
}
private static void display() {
JFrame f = new JFrame("GroupPanel");
f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
f.setLayout(new BoxLayout(f.getContentPane(), BoxLayout.Y_AXIS));
f.add(new GroupPanel(1));
f.add(new GroupPanel(2));
f.add(Box.createVerticalGlue());
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);
}
public static void main(String[] args) {
EventQueue.invokeLater(new Runnable() {
@Override
public void run() {
display();
}
});
}
}
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