如何在JFrame中将绘制的内容居中？

import javax.swing.JFrame;
import javax.swing.JPanel;

public class CenteredContentExample {
    public static void main(String[] args) {
        JFrame frame = new JFrame("Centered Content Example");
        frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE);
        frame.setSize(400, 300);
        frame.setLayout(null);

        JPanel content = new JPanel();
        content.setSize(200, 150);
        int frameWidth = frame.getWidth();
        int frameHeight = frame.getHeight();
        int contentWidth = content.getWidth();
        int contentHeight = content.getHeight();
        int x = (frameWidth - contentWidth) / 2;
        int y = (frameHeight - contentHeight) / 2;
        content.setBounds(x, y, contentWidth, contentHeight);

        frame.add(content);
        frame.setVisible(true);
    }
}