制作线程竞赛的实例。运行该程序时，能够产生一个带有三个跑道的界面，有三个黄色的圆形在竞赛谁跑得最快，到达终点后，程序结束运行。-threads contest produced examples. Run this program, to have a runway with three interfaces, three yellow circle in the competition, who ran the fastest arrival, the end of the program r