java GUI输出一个空心菱形

好的，以下是Java GUI输出一个空心菱形的代码：

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

public class Diamond extends JPanel {
    public void paintComponent(Graphics g) {
        super.paintComponent(g);
        int[] xPoints = {150, 200, 150, 100};
        int[] yPoints = {100, 150, 200, 150};
        g.drawPolygon(xPoints, yPoints, 4);
    }

    public static void main(String[] args) {
        JFrame frame = new JFrame("Diamond");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        Diamond diamond = new Diamond();
        diamond.setBackground(Color.WHITE);
        frame.add(diamond);
        frame.setSize(300, 300);
        frame.setVisible(true);
    }
}

希望这个代码可以帮到你！