java - MousEvent 不起作用，因为 MouseListener 实现行为怪异

Question

在过去的半个小时里我一直在忙这个，但我不明白为什么我的 Handlerclass 在我实现 MouseListener 和 MouseMotionListener 需要的每一个方法时总是给出一个方法不是抽象的错误。请帮忙。这是代码：

public class PanelClass extends JFrame {
private JPanel m;
private JLabel s;

public PanelClass() {
    super("Testing");

    m = new JPanel();
    m.setBackground(Color.RED);
    add(m, BorderLayout.CENTER);
    s = new JLabel("Hello and welcome. We're showing you what your mouse does in this bar. Let's get started!");
    add(s, BorderLayout.SOUTH);

    Handlerclass handler = new Handlerclass();
    m.addMouseListener(handler);
    m.addMouseMotionListener(handler);

}

private class Handlerclass implements MouseListener, MouseMotionListener {


    public void mouseClicked(MouseEvent event) {
        s.setText("You cliced the mouse.");
    }


    public void mousePressed(MouseEvent event) {
        s.setText(String.format ("You pressed the mouse"));
    }


    public void mouseReleased(MouseEvent event) {
        s.setText("You ain't clickin' shit boi..");
    }


    public void mouseEntered(MouseEvent event) {
        s.setText("The mouse has entered the panel..");
        m.setBackground(Color.PINK);
    }


    public void mouseExited(MouseEvent event) {
        s.setText("The mouse has left the panel..");
        m.setBackground(Color.BLUE);
    }

    public void mouseDragged(MouseEvent event) {
       s.setText("You been dragging. ");
    }

    public void mouseMoved(MouseEvent event) {
        s.setText("Moving around.");
    }

}

}