Swing components resizing when keyboard focus
I have two problems with the layout of my gui. I am using JTabbedPane to hold two JPanels, each panel has a set of buttons and text areas, and each is laid out using a GridBagLayout. In one of my panels, I have a JScrollPane that uses a JTextArea. When I add something to that text area and then exit the gui so that it doesn't focus anymore, or if I change the tab, all text boxes and text resize as much as possible.
To illustrate my problem again, here are the before and after snapshots when I click the gui after adding to the text area:
Here is the code that I am using to add the JTextArea to the Panel:
table = new JTextArea();
table.setEditable(false);
JScrollPane sp = new JScrollPane(table);
sp.setSize(40, 10);
c.insets = new Insets(10,10,10,10);
c.gridx = 1;
c.gridwidth = 4;
c.gridy = 7;
c.gridheight = 7;
this.add(sp, c);
And here is the code I'm using to add the Region text to the panel:
title = new JTextField(10);
author = new JTextField(10);
dueDate = new JTextField(10);
setDate = new JTextField(10);
setWeighting = new JTextField(10);
c.gridx = 2;
c.gridy = 1;
this.add(title, c);//add title field
c.gridx = 2;
c.gridy = 2;
this.add(author, c);//add author field
c.gridx = 2;
c.gridy = 3;
this.add(dueDate, c);//add dueDate field
c.gridx = 2;
c.gridy = 4;
this.add(setDate, c);//add setDate field
c.gridx = 2;
c.gridy = 5;
this.add(setWeighting, c);//add set Weighting field
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2 answers
I was able to partially reproduce your problem as follows:
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class Foo002 {
private static final int ROWS = 5;
private static void createAndShowGui() {
JPanel assignmentsPanel = new JPanel(new GridBagLayout());
final JTextArea textarea = new JTextArea(ROWS, 20);
GridBagConstraints c = new GridBagConstraints();
int insetGap = 2;
c.insets = new Insets(insetGap, insetGap, insetGap, insetGap);
c.fill = GridBagConstraints.HORIZONTAL;
c.gridwidth = 1;
c.gridheight = 1;
c.weightx = 1.0;
c.weighty = 1.0;
String[] labels = { "title", "author", "date due", "date set",
"set weighting" };
int row = 0;
for (int i = 0; i < labels.length; i++) {
JLabel label = new JLabel(labels[i], SwingConstants.CENTER);
c.gridx = 0;
c.gridy = i;
assignmentsPanel.add(label, c);
c.gridx = 1;
JTextField textfield = new JTextField(10);
assignmentsPanel.add(textfield, c);
label.setPreferredSize(textfield.getPreferredSize());
row++;
}
c.gridx = 0;
c.gridy = row;
c.fill = GridBagConstraints.HORIZONTAL;
Action myAction = new AbstractAction("Fill Area") {
@Override
public void actionPerformed(ActionEvent arg0) {
StringBuilder sb = new StringBuilder();
for (int i = 0; i < 10; i++) {
sb.append("foo bar bif baz spam\n");
}
textarea.setText(sb.toString());
}
};
assignmentsPanel.add(new JButton(myAction), c);
c.gridx = 1;
assignmentsPanel.add(new JButton("Button 2"), c);
row++;
c.gridx = 0;
c.gridy = row;
c.gridwidth = 2;
c.gridheight = ROWS;
JScrollPane scrollpane = new JScrollPane(textarea);
assignmentsPanel.add(scrollpane, c);
JTabbedPane tabbedPanel = new JTabbedPane();
tabbedPanel.add("Assignments", assignmentsPanel);
tabbedPanel.add("Modules", new JPanel());
JOptionPane.showMessageDialog(null, tabbedPanel, "Foo",
JOptionPane.PLAIN_MESSAGE);
}
public static void main(String[] args) {
SwingUtilities.invokeLater(new Runnable() {
public void run() {
createAndShowGui();
}
});
}
}
Before and after adding text to the JTextArea, it looks like this:
And after clicking on the tabs: 
But this can be fixed by giving the JScrollPane a vertical scrollbar:
// JScrollPane scrollpane = new JScrollPane(textarea);
JScrollPane scrollpane = new JScrollPane(textarea,
JScrollPane.VERTICAL_SCROLLBAR_ALWAYS,
JScrollPane.HORIZONTAL_SCROLLBAR_NEVER);
What looks like this at startup: 
Looks good on Mac OS too:
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You can try to refrain from using Gridbag and use nested JPanels instead. I allowed to create a short example:
public class LilrooPanel extends JPanel
{
private static final int GAP = 5;
public static void main(String[] args){
JFrame main = new JFrame("Dims");
JTabbedPane tabbed = new JTabbedPane();
JPanel myPanel = new LilrooPanel();
tabbed.add("Assignments", myPanel);
tabbed.add("Modules", new JPanel());
main.setContentPane(tabbed);
main.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
main.setSize(400, 400);
main.setLocationRelativeTo(null);
main.setVisible(true);
}
public LilrooPanel(){
super(new BorderLayout(0, GAP));
setBorder(BorderFactory.createEmptyBorder(GAP, GAP, GAP, GAP));
Box north = new Box(BoxLayout.Y_AXIS);
north.add(new BorderPanel("Assignment Title", new JTextField()));
north.add(Box.createRigidArea(new Dimension(0, GAP)));
north.add(new BorderPanel("Author", new JTextField()));
north.add(Box.createRigidArea(new Dimension(0, GAP)));
north.add(new BorderPanel("Date Due", new JTextField()));
north.add(Box.createRigidArea(new Dimension(0, GAP)));
north.add(new BorderPanel("Date Set", new JTextField()));
north.add(Box.createRigidArea(new Dimension(0, GAP)));
north.add(new BorderPanel("Set Weighting", new JTextField()));
north.add(Box.createRigidArea(new Dimension(0, GAP)));
JPanel buttonsPanel = new JPanel();
buttonsPanel.add(new JButton("Add Assignment"));
buttonsPanel.add(new JButton("Remove Assignment"));
north.add(buttonsPanel);
add(north, BorderLayout.NORTH);
add(new JScrollPane(new JTable(new Object[][]{}, new Object[]{"ModTitle", "ModId", "Assignments"})));
}
private static class BorderPanel extends JPanel
{
private static final Dimension LABELS_WIDTH = new Dimension(100, 0);
public BorderPanel(String label, JComponent right){
super(new BorderLayout(GAP, 0));
JLabel jLabel = new JLabel(label);
jLabel.setPreferredSize(LABELS_WIDTH);
add(jLabel, BorderLayout.WEST);
add(right);
}
}
}
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