我的监听器不能实现

public void mouseClicked(MouseEvent e) {

// TODO Auto-generated method stub

System.out.println("鼠标点击");

JOptionPane.showMessageDialog(this,"鼠标点击");

}

public void mouseEntered(MouseEvent e) {

// TODO Auto-generated method stub

System.out.println("鼠标进入");

JOptionPane.showMessageDialog(this,"鼠标进入");

}

public void mouseExited(MouseEvent e) {

// TODO Auto-generated method stub

}

public void mousePressed(MouseEvent e) {

// TODO Auto-generated method stub

}

public void mouseReleased(MouseEvent e) {

// TODO Auto-generated method stub

}