Why is my JPanel messing with other components on my JFrame?

Question

So I have a JFrame which contains a JPanel that holds a JList component.

Then I have another JPanel for my paintComponent() which also returns a dimension.

But when I set the size for the dimension, it tries to relocate my other JPanel.

Here is my code for the paintComponent():

class drawOnPanel extends JPanel {
    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setColor(Color.BLUE);
    }
    @Override
  public Dimension getPreferredSize(){
    return new Dimension(250, 250);
  }
}

Then I have my JFrame which calls the drawOnPanel class:

public static void mainFrame() {
    JFrame f = new MTGSAMPServerReference();
    f.setTitle("MTG SAMP Server Reference Guide");
    f.pack();
    f.setVisible(true);
    f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
    f.add(new drawOnPanel());
    f.setSize(330, 300);
    f.setLocationRelativeTo(null);
}

And then I have my JList which is on my JPanel:

public void MainMenu() {
    JPanel controls = new JPanel(new BorderLayout(5,5));
    final CardLayout cl = new CardLayout();
    final JPanel panel = new JPanel(cl);
    controls.add(panel);
    this.getContentPane().setLayout(new FlowLayout(FlowLayout.LEADING));
        list = new JList<Object>(mainMenu);
        list.setVisibleRowCount(7);
        select = new JButton("Select");
        exit = new JButton("Exit");
        select.addActionListener(this);
        exit.addActionListener(this);
        controls.add(new JScrollPane(list));
        JPanel basePanel = new JPanel(new GridLayout(0, 1));
        basePanel.add(select);
        basePanel.add(exit);
        controls.add(basePanel, BorderLayout.PAGE_END);
        add(controls);
        refreshFrame();
}

When I try to draw on my paintComponent() JPanel, it draws, but the coordinates that I indicate are not correctly drawn.

Does anyone know why this is happening?

Thanks in advance!

EDIT: Here are some screenshots of my program.

This one is what my program looks like when I don't include drawOnPanel: No drawOnPanel

And this one is what my program looks like when I include drawOnPanel: With drawOnPanel

I just want it to draw on the right side of the JList, without moving the JList. As you can see, it adjusts the other JPanel.

Any and all help is appreciated!

EDIT: Here is my SSCCE.

EDIT: Here is my SSCCE code:

import java.awt.*;
import java.awt.event.*;
import javax.swing.*;

public final class SSCCE1 extends JFrame implements ActionListener {
    private static final long serialVersionUID = 1L;
    JList list;
    JButton select;
    JButton exit;
    Object[]mainMenu = {"Value 1", "Value 2", "Value 3", "Value 4"};

    public SSCCE1() {
        MainMenu();
    }

    public void MainMenu() {
        JPanel controls = new JPanel(new BorderLayout(5,5));
        final CardLayout cl = new CardLayout();
        final JPanel panel = new JPanel(cl);
        controls.add(panel);
        this.getContentPane().setLayout(new FlowLayout(FlowLayout.LEADING));
            list = new JList<Object>(mainMenu);
            list.setVisibleRowCount(7);
            select = new JButton("Select");
            exit = new JButton("Exit");
            controls.add(new JScrollPane(list));
            JPanel basePanel = new JPanel(new GridLayout(0, 1));
            basePanel.add(select);
            basePanel.add(exit);
            controls.add(basePanel, BorderLayout.PAGE_END);
            add(controls);
            revalidate();
            repaint();
            SSCCE1.this.repaint();
    }

    public void createAndShowGUI() {
        mainFrame();
        SSCCE1.this.repaint();
    }

    public static void mainFrame() {
        JFrame f = new SSCCE1();
        f.setTitle("My SSCCE");
        f.pack();
        f.setVisible(true);
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(new drawOnPanel()); // When this is uncommented, it messes with the other JPanel, but when commented, it works fine, but does not allow drawing on the other JFrame.
        f.setExtendedState(JFrame.MAXIMIZED_BOTH);
        f.setLocationRelativeTo(null);
    }

    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
            SSCCE1 gui = new SSCCE1();
            gui.createAndShowGUI();
            }
        });
    }
    @Override
    public void actionPerformed(ActionEvent ae) {
    }
}

class drawOnPanel extends JPanel {
    @Override
    protected void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2 = (Graphics2D)g;
        g2.setRenderingHint(RenderingHints.KEY_ANTIALIASING, RenderingHints.VALUE_ANTIALIAS_ON);
        g2.setColor(Color.BLUE);
    }
  @Override
  public Dimension getPreferredSize(){
    return new Dimension(250, 250);
  }
}

It looks like a layout issue, but without a runnable example, it's going to be difficult to figure out why — MadProgrammer, Aug 04 '13 at 01:35
@MadProgrammer What would be the best way to debug this? I was looking for an interactive compiler that shows you what each component is when you click on it, but couldn't find one... I did get a program called PixelWindow to help me figure out why the pixel locations were off, but the problem changes constantly on that part. What would you suggest I do? — knorberg, Aug 04 '13 at 01:46

score 3 · Answer 1 · edited May 23 '17 at 12:11

3

Make setVisible() last, after a adding, packing and locating. Complete examples are seen here and here.

f.add(…);
f.pack();
f.setLocationRelativeTo(null);
f.setVisible(true);

Addendum: Here's a variation on your example, without the invisible panel. Absent a compelling reason to extend JFrame, just create one and add your components.

import java.awt.*;
import javax.swing.*;

/** @see https://stackoverflow.com/a/18038765/230513 */
public class SSCCE2 {

    private JList list;
    private JButton select;
    private JButton exit;
    private Object[] mainMenu = {"Value 1", "Value 2", "Value 3", "Value 4"};

    public JPanel mainMenu() {
        JPanel controls = new JPanel(new BorderLayout(5, 5));
        list = new JList(mainMenu);
        list.setVisibleRowCount(7);
        select = new JButton("Select");
        exit = new JButton("Exit");
        controls.add(new JScrollPane(list));
        JPanel basePanel = new JPanel(new GridLayout(0, 1));
        basePanel.add(select);
        basePanel.add(exit);
        controls.add(basePanel, BorderLayout.PAGE_END);
        return controls;
    }

    public void createAndShowGUI() {
        JFrame f = new JFrame("My SSCCE");
        f.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        f.add(new DrawOnPanel());
        f.add(mainMenu(), BorderLayout.WEST);
        f.pack();
        f.setLocationRelativeTo(null);
        f.setVisible(true);
    }

    public static void main(String[] args) {
        javax.swing.SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                SSCCE2 gui = new SSCCE2();
                gui.createAndShowGUI();
            }
        });
    }

    private static class DrawOnPanel extends JPanel {

        @Override
        protected void paintComponent(Graphics g) {
            super.paintComponent(g);
            g.setColor(Color.BLUE);
            g.fillRect(0, 0, getWidth(), getHeight());
        }

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(250, 250);
        }
    }
}

edited May 23 '17 at 12:11

Community

1
1

answered Aug 04 '13 at 00:54

trashgod

203,806
29
246
1,045

I am just rearranging them to the order you said. – knorberg Aug 04 '13 at 01:00
2

@knorberg: then if it's not working, there's something wrong in code you're not yet shown us. Strongly consider creating and posting an [sscce](http://sscce.org). While this will require a fair amount of effort to create, it is effort well spent, believe me. – Hovercraft Full Of Eels Aug 04 '13 at 02:17
@HovercraftFullOfEels I have now posted an SSCCE. – knorberg Aug 04 '13 at 03:04
@knorberg: you need to post your SSCCE here in your question not as a link. – Hovercraft Full Of Eels Aug 04 '13 at 03:21
@HovercraftFullOfEels Oh. Sorry about that. – knorberg Aug 04 '13 at 03:23
@knorberg: I'll 1+ that. – Hovercraft Full Of Eels Aug 04 '13 at 03:42
@trashgod Instead of `JFrame f = new SSCCE1();`, should I do `JFrame f = new JFrame();`? – knorberg Aug 04 '13 at 03:46
In effect, yes; more above. – trashgod Aug 04 '13 at 03:56
@trashgod I can't seem to get this to work with all of my code. The way I have my code setup (I use different methods to display the list with different contents depending on user input) does not work with the way that you have set up yours. Any other suggestions? – knorberg Aug 04 '13 at 04:13
I addressed the layout aspect of the problem; I'd update the list's model to change its contents depending on user input. – trashgod Aug 04 '13 at 04:29

Why is my JPanel messing with other components on my JFrame?

1 Answers1