Invisible components still take up space JPanel

Question

I have a series of components underneath each other in a JPanel set as a GridLayout. I need to temporarily hide the components but setVisible(false) doesn\'t cu

Answer 1

don't call Thread.sleep(int); during EDT, because block EDT, use javax.swing.Timer

for example

import java.awt.Color;
import java.awt.GridLayout;
import java.awt.event.ActionEvent;
import javax.swing.*;
import javax.swing.border.*;

public class SSCCE extends JFrame {

    private static final long serialVersionUID = 1L;
    private JPanel innerPane = new JPanel();
    private JScrollPane scr = new JScrollPane(innerPane);
    private Timer timer;

    public static void main(String[] args) {
        SwingUtilities.invokeLater(new Runnable() {

            @Override
            public void run() {
                SSCCE sSCCE = new SSCCE();
            }
        });
    }

    private JPanel getPane() {
        JPanel ret = new JPanel();
        JLabel lbl = new JLabel("This is a pane.");
        ret.add(lbl);
        ret.setBorder(BorderFactory.createBevelBorder(BevelBorder.RAISED));
        ret.setBackground(Color.gray);
        return ret;
    }

    public SSCCE() {
        innerPane.setLayout(new GridLayout(0, 1));
        add(scr);
        for (int i = 0; i < 30; i++) {
            innerPane.add(getPane());
        }
        setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        pack();
        setVisible(true);
        start();
    }

    private void start() {
        timer = new javax.swing.Timer(2000, updateCol());
        timer.start();
        timer.setRepeats(false);
    }

    private Action updateCol() {
        return new AbstractAction("Hide Row Action") {

            private static final long serialVersionUID = 1L;

            @Override
            public void actionPerformed(ActionEvent e) {
                for (int i = 0; i < 30; i++) {
                    if (i % 2 == 0) {
                        innerPane.getComponent(i).setVisible(false);
                    }
                }
            }
        };
    }
}