Question

java中的repaint方法

为什么要重绘，老师好像讲的是paint是自动调用的不是吗？不是每操作一次就会调用一次吗，repaint是什么
还是说之后调用paint不会直接在显示出来，所以才repaint

Answer 1

我的理解如下，老师讲的有欠缺，没有讲清楚这个方法的使用范围
java里repaint()是重绘component的方法；
component中己有的图形发生变化后不会立刻显示，须使用repaint方法。

Answer 2

球球了，看个源码吧，里面都有些
第一行就是， repaints this component
/**
* Repaints this component.
* <p>
* If this component is a lightweight component, this method
* causes a call to this component's {@code paint}
* method as soon as possible. Otherwise, this method causes
* a call to this component's {@code update} method as soon
* as possible.
* <p>
* <b>Note</b>: For more information on the paint mechanisms utilitized
* by AWT and Swing, including information on how to write the most
* efficient painting code, see
* <a href="http://www.oracle.com/technetwork/java/painting-140037.html">Painting in AWT and Swing</a>.

*
* @see #update(Graphics)
* @since 1.0
*/