Re: Adding Component above all other components

From:
Knute Johnson <nospam@rabbitbrush.frazmtn.com>
Newsgroups:
comp.lang.java.gui
Date:
Sat, 16 Aug 2008 09:00:53 -0700
Message-ID:
<48a6f9b5$0$4046$b9f67a60@news.newsdemon.com>
Royan wrote:

On 16 ???, 15:06, Royan <romayan...@gmail.com> wrote:

My initial problem is to put the panel (which is created as a result
of a click on a button) above all components that have been added to
the GBLTablePanel. I've written the following sample that demonstrates
my problem

package test;

import java.awt.Dimension;
import java.awt.GridBagConstraints;
import java.awt.GridBagLayout;
import java.awt.event.ActionEvent;

import javax.swing.AbstractAction;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JLabel;
import javax.swing.JPanel;
import javax.swing.JScrollPane;
import javax.swing.JTable;
import javax.swing.WindowConstants;
import javax.swing.table.DefaultTableModel;

public class GBLTablePanel extends JPanel {
    private final GridBagLayout layout;
    private final GridBagConstraints gbc;

    public GBLTablePanel() {
        layout = new GridBagLayout();
        gbc = new GridBagConstraints();
        setLayout(layout);

        JTable table = new JTable();

        table.setModel(new DefaultTableModel(new Object[][] {
                { "aaaaaaaaaaaaaaa", 3, "a", null }, { "adasda", 10, "b", null },
                { "aaaaaaaaaaaaaaa", 3, "a", null }, { "adasda", 10, "b", null },
                { "aaaaaaaaaaaaaaa", 3, "a", null }, { "adasda", 10, "b", null },
                { "aaaaaaaaaaaaaaa", 3, "a", null }, { "adasda", 10, "b", null },
                { "assssss", 55, "c", null }, { "asdafasfa", 44, "d", null } },
                new String[] { "Title 1", "Title 2", "Title 3", "Title 4" }));

        JScrollPane scrollPane = new JScrollPane(table);

        gbc.gridx = 0;
        gbc.gridy = 0;
        gbc.fill = GridBagConstraints.BOTH;
        gbc.weightx = 1.0;
        gbc.weighty = 1.0;
        layout.setConstraints(scrollPane, gbc);

        add(scrollPane);

        JButton showPanelBtn = new JButton(new AbstractAction("Show panel") {
            @Override
            public void actionPerformed(ActionEvent e) {

                /* When this button is clicked I want that panel to appear on the
top (above all components of the GBLTablePanel ) */
                JPanel panel = new JPanel();
                panel.add(new JLabel("This must be on the top of JTable"));
                panel.setSize(panel.getSize().width, 30);
                panel.setPreferredSize(new Dimension(panel.getPreferredSize().width,
30));

                layout.setConstraints(panel, gbc);
                gbc.gridy = 0;
                GBLTablePanel.this.add(panel, 0);
            }
        });

        gbc.gridwidth = GridBagConstraints.REMAINDER;
        gbc.gridy = 1;
        layout.setConstraints(scrollPane, gbc);
        add(showPanelBtn);
    }

    public static void main(String[] args) {
        JFrame f = new JFrame("Test");
        f.setDefaultCloseOperation(WindowConstants.EXIT_ON_CLOSE);

        /* Construct table managed by GridBagLayout */
        GBLTablePanel panel = new GBLTablePanel();
        f.add(panel);
        f.pack();
        f.setVisible(true);
    }

}

I hope the example is not too confusing, honestly I'm not sure what do
I try next to fix my problem. The panel simply does not show up :(


OK it seems like calling validate/revalidate:

GBLTablePanel.this.add(panel, 0);
GBLTablePanel.this.revalidate();

will make JLabel visible, but thus JTable gets disappeared, why?!?!


You can't put components on top of each other with GridBagLayout or any
layout manager for that matter. If you want stacked components you can
use the JLayeredPane but you have to size and position your components
manually. In the example below the JLabel is on the JLayeredPane and
that is above the ContentPane where the JPanel is located. The
commented out code will put the blue JPanel on the JLayeredPane as well.

import java.awt.*;
import java.awt.event.*;
import java.awt.image.*;
import java.io.*;
import javax.imageio.*;
import javax.swing.*;

public class test extends JFrame {
     public test() {
         setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);

         JLayeredPane lp = getLayeredPane();
         lp.setPreferredSize(new Dimension(400,300));

         JPanel p = new JPanel();
         p.setBackground(Color.BLUE);
// p.setSize(400,300);
// lp.setLayer(p,10);
// lp.add(p);
         add(p);

         JLabel l = new JLabel("this is on top of the panel");
         l.setForeground(Color.WHITE);
         l.setSize(l.getPreferredSize());
         l.setLocation(20,100);
         l.setOpaque(false);
         lp.setLayer(l,11);
         lp.add(l);

         setSize(400,300);
         setVisible(true);
     }

     public static void main(String[] args) {
         EventQueue.invokeLater(new Runnable() {
             public void run() {
                 new test();
             }
         });
     }
}

--

Knute Johnson
email s/nospam/knute2008/

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