小编Wes*_*son的帖子

下面写在BasicLinePix类中我尝试创建一个程序,允许用户通过按住shift键同时按住鼠标按钮并将其拖动到端点来绘制线条.问题是,当鼠标被释放时,该行消失.我试图让线条显示在面板中,以及显示以相同方式绘制的多条线条.

我的代码看起来像:

    // this method overrides the paint method defined in JFrame
    public void paint(Graphics g) {
        super.paint(g);


    }


    // Inner class - instances of this class handle action events
    private class EventHandler implements ActionListener, MouseListener,
            MouseMotionListener {

        private Point startPoint = null; // line's start point
        private Point endPoint = null; // line's most recent end point

        public void actionPerformed(ActionEvent arg0) {
            if (arg0.getActionCommand().equals("Exit")) {
                statusLabel.setText("Exiting program...");
                System.exit(0);
            }

        }

        @Override
        public void mouseClicked(MouseEvent arg0) {
            // TODO Auto-generated …