Unwanted Images Appearing on Java Button - image

Question

I'm trying to use a polygon shaped button in Java. I found this code for this purpose:
package testklassen;
import java.awt.Graphics;
import java.awt.Graphics2D;
import java.awt.Point;
import java.awt.Polygon;
import javax.swing.JButton;
import javax.swing.JFrame;
import javax.swing.JPanel;
public class PolygonButton extends JButton {
private Polygon shape;
public PolygonButton(int[] x, int[] y) {
this.shape = new Polygon();
this.initialize(x, y);
}
protected void initialize(int[] x, int[] y) {
Point p1, p2, p3, p4, p5;
this.setSize(90, 120);
p1 = new Point(x[0], y[0]);
p2 = new Point(x[1], y[1]);
p3 = new Point(x[2], y[2]);
p4 = new Point(x[3], y[3]);
p5 = new Point(x[4], y[4]);
this.shape.addPoint((int) Math.round(p1.getX()),
(int) Math.round(p1.getY()));
this.shape.addPoint((int) Math.round(p2.getX()),
(int) Math.round(p2.getY()));
this.shape.addPoint((int) Math.round(p3.getX()),
(int) Math.round(p3.getY()));
this.shape.addPoint((int) Math.round(p4.getX()),
(int) Math.round(p4.getY()));
this.shape.addPoint((int) Math.round(p5.getX()),
(int) Math.round(p5.getY()));
this.setMinimumSize(this.getSize());
this.setMaximumSize(this.getSize());
this.setPreferredSize(this.getSize());
}
// Hit detection
public boolean contains(int x, int y) {
return this.shape.contains(x, y);
}
// Draw Button
protected void paintComponent(Graphics g) {
Graphics2D gCopy = (Graphics2D) g.create();
gCopy.fillPolygon(this.shape);
}
}
To test this, I build a simple frame containing a PolygonButton and a normal Button:
package testklassen;
import java.awt.*;
import java.awt.event.*;
import javax.swing.*;
public class FrameForPolygonButton extends JFrame {
int[] x = {0, 50, 100, 100, 0};
int[] y = {0, 50, 0, 100, 100};
PolygonButton polygonButton = new PolygonButton(x, y);
JButton button = new JButton();
public FrameForPolygonButton() {
super();
setDefaultCloseOperation(WindowConstants.DISPOSE_ON_CLOSE);
int frameWidth = 530;
int frameHeight = 400;
setSize(frameWidth, frameHeight);
Dimension d = Toolkit.getDefaultToolkit().getScreenSize();
int x = (d.width - getSize().width) / 2;
int y = (d.height - getSize().height) / 2;
setLocation(x, y);
setResizable(false);
Container cp = getContentPane();
cp.setLayout(null);
setVisible(true);
button.setBounds(200, 200, 50, 50);
cp.add(button);
//polygonButton.setBorder(null);
cp.add(polygonButton);
}
public static void main(String[] args) {
new FrameForPolygonButton();
}
}
That's how it looks like when starting. And that is exactly what I want.
But when I hover over the other JButton and then hover back over the PolygonButton
a picture of the JButton appears on the PolygonButton
Does anyone know, how I can avoid this?

Answer 1

I found out a solution for this problem. But I still don't know, why this was happening in the first place. If someone does know, I would be interested.
The solution, that worked vor me was to add this line:
polygonButton.setOpaque(false);