import java.awt.*;
import javax.swing.*;
import javax.swing.event.*;
public class SliderFace {
public static void main(String[] args) {
JSlider slider = new JSlider();
JPanel panel = new JPanel() {
public void paintComponent(Graphics g) {
super.paintComponent(g);
double r = (double)slider.getValue() / slider.getMaximum();
int w = getWidth(), h = getHeight();
int a = w / 10, b = h / 5, c = (int)(b * r);
g.drawLine(a * 2, b * 1 + c, a * 4, b * 2 - c);
g.drawLine(a * 6, b * 2 - c, a * 8, b * 1 + c);
g.drawLine(a * 3, b * 4 - c, a * 5, b * 3 + c);
g.drawLine(a * 5, b * 3 + c, a * 7, b * 4 - c);
}
};
slider.addChangeListener(e -> panel.repaint());
panel.setPreferredSize(new Dimension(250, 250));

JFrame frame = new JFrame("課題");
frame.getContentPane().add(slider, BorderLayout.NORTH);
frame.getContentPane().add(panel, BorderLayout.CENTER);
frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
frame.pack();
frame.setVisible(true);
}
}