I've seen two other posts on stackoverflow about this and in both, the solutions use setConstraints(myComponent, anotherConstraint)
which doesn't even come up as an available method when I try to use it in java.
want to change an Inset in a gridbag layout dynamically
Change the component weight dynamically in GridBagLayout
How else could I change the weightx
of a component after a button press?
The actual problem is that I have two components at the bottom of the screen and I need to set one of the components to be the max width of the screen after a button press.
I couldn't get
setConstraints()
to work..
Then it seems the code was wrong. From the fact the RHS of the red panel neatly aligns with the LHS of the Articuno
label I suspect that the grid bag cell containing the red panel does not span more than one column, and currently entirely fills that column.
There could be other reasons, but short a minimal reproducible example I won't speculate further.
Here is a simplified example showing how to do it. Note that it was necessary to call revalidate()
before the changes could be seen.
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
import javax.swing.border.*;
import java.awt.image.BufferedImage;
public class FullWidthToggle {
private JComponent ui = null;
FullWidthToggle() {
initUI();
}
public final void initUI() {
if (ui != null) {
return;
}
GridBagConstraints gbc = new GridBagConstraints();
GridBagLayout gbl = new GridBagLayout();
ui = new JPanel(gbl);
ui.setBorder(new EmptyBorder(4, 4, 4, 4));
BufferedImage image = new BufferedImage(
160, 20, BufferedImage.TYPE_INT_RGB);
gbc.insets = new Insets(5, 5, 5, 5);
ui.add(new JLabel(new ImageIcon(image)), gbc);
final JCheckBox checkBox = new JCheckBox("Full Width");
gbc.gridx = 1;
gbc.anchor = GridBagConstraints.LINE_START;
ui.add(checkBox, gbc);
final JLabel label = new JLabel("Am I full width?");
label.setBorder(new LineBorder(Color.RED, 2));
gbc.gridx = 0;
gbc.gridy = 1;
gbc.gridwidth = 2;
ui.add(label, gbc);
ActionListener actionListener = (ActionEvent e) -> {
if (checkBox.isSelected()) {
gbc.fill = GridBagConstraints.HORIZONTAL;
} else {
gbc.fill = GridBagConstraints.NONE;
}
gbl.setConstraints(label, gbc);
ui.revalidate(); // <- important!
};
checkBox.addActionListener(actionListener);
}
public JComponent getUI() {
return ui;
}
public static void main(String[] args) {
Runnable r = () -> {
try {
UIManager.setLookAndFeel(UIManager.getSystemLookAndFeelClassName());
} catch (Exception useDefault) {
}
FullWidthToggle o = new FullWidthToggle();
JFrame f = new JFrame(o.getClass().getSimpleName());
f.setDefaultCloseOperation(JFrame.DISPOSE_ON_CLOSE);
f.setLocationByPlatform(true);
f.setContentPane(o.getUI());
f.pack();
f.setMinimumSize(f.getSize());
f.setVisible(true);
};
SwingUtilities.invokeLater(r);
}
}