一个可以来回动的小球，主要是在单文档条件下的一种动态图像的实现。-A ball moving back and forth, mainly in the Single Document under the conditions of the realization of a dynamic image.

用java实现一个小球的程序，当点击开始按钮就会启动一个小球线程，并且小球在面板内移动。-To achieve with a small ball java process, when the click the Start button will start a thread ball and small ball moving in the panel.