paintComponent not visible java

Question

I want to add this into another JPanel but it's not visible there. My other Jpanel is called bottomPanel. The paintComponent is supposed to display in the bottom Panel

 bottomPanel.setLayout(null);  
 TestPane tp = new TestPane();
 bottomPanel.add(tp);

I have extended the Jpanel.

  public class TestPane extends JPanel {
  @Override
   public Dimension getPreferredSize() {
        return new Dimension(200, 200);
    }


    @Override
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        Graphics2D g2d = (Graphics2D) g.create();
        int width = getWidth() - 100;
        int height = getHeight() - 100;
        int x = (getWidth() - width) / 2;
        int y = (getHeight() - height) / 2;
        g2d.setColor(Color.RED);
        g2d.drawRect(x, y, width, height);
        g2d.dispose();
    }

}

How are you adding the panel to the parent container? How is this getting dsplaying on the screen? — MadProgrammer, Apr 06 '17 at 01:19
bottomPanel is another panel which i want this to display in. isn't bottomPanel.add(new TestPane()); enough for it? sorry I am new to java — hello12345678, Apr 06 '17 at 01:27
We don't need a screenshot, we need the code that reproduces your problem. — Erwin Bolwidt, Apr 06 '17 at 02:01
Once a compilable, runnable code example has been added. **don't remove it in later edits!** — Andrew Thompson, Apr 06 '17 at 02:13

score 3 · Accepted Answer · edited May 23 '17 at 11:54

The problem starts with:

bottomPanel.setLayout(null);

Java GUIs have to work on different OS', screen size, screen resolution etc. using different PLAFs in different locales. As such, they are not conducive to pixel perfect layout. Instead use layout managers, or combinations of them along with layout padding and borders for white space.

And in future, post an MCVE rather than over 300 lines of code with irrelevant additions like file I/O, tables, row sorters etc.

score 2 · Answer 2 · edited May 23 '17 at 12:02

Works for me...

import java.awt.BorderLayout;
import java.awt.Color;
import java.awt.Dimension;
import java.awt.Graphics;
import java.awt.Graphics2D;
import javax.swing.JFrame;
import javax.swing.JPanel;
import javax.swing.SwingUtilities;

public class Test {

    public static void main(String[] args) {
        new Test();
    }

    public Test() {
        SwingUtilities.invokeLater(new Runnable() {
            @Override
            public void run() {
                JFrame frame = new JFrame();
                JPanel outer = new JPanel(new BorderLayout());
                outer.add(new TestPane());
                frame.add(outer);
                frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
                frame.pack();
                frame.setLocationRelativeTo(null);
                frame.setVisible(true);
            }
        });
    }

    public class TestPane extends JPanel {

        @Override
        public Dimension getPreferredSize() {
            return new Dimension(200, 200);
        }

        @Override
        public void paintComponent(Graphics g) {
            super.paintComponent(g);
            Graphics2D g2d = (Graphics2D) g.create();
            int width = getWidth() - 100;
            int height = getHeight() - 100;
            int x = (getWidth() - width) / 2;
            int y = (getHeight() - height) / 2;
            g2d.setColor(Color.RED);
            g2d.drawRect(x, y, width, height);
            g2d.dispose();
        }

    }

}

Consider providing a runnable example which demonstrates your problem

@hello12345678 It works fine for me, show me it not working - it's even embedded inside another panel and it still works — MadProgrammer, Apr 06 '17 at 01:36
No [runnable example](http://stackoverflow.com/help/mcve) no reliable answer - everything else is guess work — MadProgrammer, Apr 06 '17 at 01:44

paintComponent not visible java

2 Answers2