java - 从 JButton 创建 slider

Question

我在 JPanel 上有 JTextField 和 JButton。我想向 JButton 添加监听器，这样当我按下按钮并移动鼠标时，文本字段值开始改变(当我向右移动鼠标时增加，当我向左移动鼠标时减少)。所以它有点像 slider 。这是代码

 final JPanel panel=new JPanel();
 final JTextField text = new JTextField("10");
 JButton button=new JButton("f");
 panel.add(text);
 panel.add(button);

 button.addMouseListener(new MouseAdapter(){
        @Override
        public void mousePressed(final MouseEvent evt){

        //here we add listener to read mouse position when mouse pressed on button
        panel.addMouseListener(new MouseAdapter(){

                int x1 = evt.getXOnScreen();

                int x2;

                @Override
                public void mouseMoved(MouseEvent e){
                    // this method is never called
                    x2=e.getXOnScreen();
                    //increase(decrese) number in textfield by 1% for every moved pixel
                    double d = (x2-x1)*0.01+Double.parseDouble(text.getText());
                    text.setText(Double.toString(d));
                    x1=x2;

                                                    }


                                              });

                        }
       // now, when mouse released we should remove listener from panel
        @Override
        public void mouseReleased(final MouseEvent evt){
            MouseListener[] ml = panel.getListeners(MouseListener.class);
            panel.removeMouseListener(ml[0]);


        }
    });

问题是，永远不会调用 panelListener 的 mouseMoved 方法。我该怎么办？

Answer 1

就用

panel.addMouseMotionListener(...)

代替:

panel.addMouseListener(...)

来自 Java Docs :

public interface MouseListener: The listener interface for receiving "interesting" mouse events (press, release, click, enter, and exit) on a component. (To track mouse moves and mouse drags, use the MouseMotionListener.)