Java 鼠标的坐标？

当我将鼠标移动到边框时，它不是（0,0）。为什么？例如，我将鼠标移动到左上角，它显示的是（4,30）而不是（0,0）。

将MouseListener或MouseMotionListener添加到JFrame的contentPane，而不是JFrame本身，否则您必须担心边框、菜单、插图等。例如：

public class mouse extends JFrame {
    private int x, y;
    private JLabel label;

    public mouse() {
        JPanel panel = new JPanel();
         addMouseMotionListener(new MouseMotion());
         label = new JLabel();
         panel.add(label);
         setPreferredSize(new Dimension(400, 200));
         add(panel, BorderLayout.SOUTH);
         pack();
         setVisible(true);
    }
    private class MouseMotion extends MouseMotionAdapter {
        public void mouseMoved(MouseEvent e) {
            x = e.getX();
            y = e.getY();
            label.setText("mouse coordinate " + "(" + x + "," + y + ")");
    }}
    public static void main(String[]args) {
        mouse a = new mouse();
    }
}

另外，请格式化您的代码以便我们阅读

getContentPane().addMouseMotionListener(new MouseMotion());