J2ME实现小球在屏幕上弹跳，碰到屏幕边缘后回弹并改变颜色，可供J2ME学习使用，代码非常简洁，算法清楚简单-J2ME the ball bounce on the screen, the rebound after encounter the edge of the screen and change the color, available J2ME learn to use, the code is very simple, clear and simple algorithm