如何在Java awt中合并形状？

import java.awt.*;
import java.awt.geom.*;

public class ShapeMergeExample extends Frame {
    public void paint(Graphics g) {
        Graphics2D g2d = (Graphics2D) g;

        // 创建一个矩形形状
        Rectangle2D rect = new Rectangle2D.Double(50, 50, 200, 100);

        // 创建一个椭圆形状
        Ellipse2D ellipse = new Ellipse2D.Double(150, 100, 200, 100);

        // 设置合并模式为合并
        g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.SRC_OVER));

        // 绘制矩形
        g2d.setColor(Color.RED);
        g2d.fill(rect);

        // 设置合并模式为相交
        g2d.setComposite(AlphaComposite.getInstance(AlphaComposite.DST_IN));

        // 绘制椭圆
        g2d.setColor(Color.BLUE);
        g2d.fill(ellipse);
    }

    public static void main(String[] args) {
        ShapeMergeExample example = new ShapeMergeExample();
        example.setSize(400, 300);
        example.setVisible(true);
    }
}