请问发生以下错误时，一般是什么问题？
Multiple markers at this line
- The type drawline.handle must implement the inherited abstract method
MouseMotionListener.mouseMoved(MouseEvent)
- The serializable class handle does not declare a static final serialVersionUID field of type long
- The type drawline.handle must implement the inherited abstract method MouseListener.mouseClicked(MouseEvent)
------解决方案--------------------
问题说的挺清楚的：
- The type drawline.handle must implement the inherited abstract method
MouseMotionListener.mouseMoved(MouseEvent)
- 类型drawline.handle必须实现继承的抽象方法MouseMotionListener.mouseMoved(MouseEvent)
说明：类型drawline.handle的祖先有个抽象方法MouseMotionListener.mouseMoved(MouseEvent)，还没有实现，就想实例化这个类导致的。
- The serializable class handle does not declare a static final serialVersionUID field of type long
- 可序列化类句柄未声明一个long类型的static final serialVersionUID 成员（那就声明一个呗）
- The type drawline.handle must implement the inherited abstract method MouseListener.mouseClicked(MouseEvent)
- 与问题1类似