package?com.imooc; import?java.awt.*; import?java.awt.event.*; import?java.applet.*; public?class?BallThread?extends?Applet?implements?Runnable{ Thread?red,?blue; Graphics?redPen,?bluePen; int?t=0; public?void?init(){ red?=?new?Thread(this); blue?=?new?Thread(this); redPen?=?getGraphics(); bluePen?=?getGraphics(); redPen.setColor(Color.red); bluePen.setColor(Color.blue); } public?void?start(){ red.start(); blue.start(); } public?void?run(){ while(true){ t=t+1; if(Thread.currentThread()==red){ if(t>100)t=0; redPen.clearRect(0,0,110,400); redPen.fillOval(50,(int)(1.0/2*t*9.8),15,15); try{ red.sleep(40); }catch(InterruptedException?e){} }else?if(Thread.currentThread()==blue){ bluePen.clearRect(120,0,900,500); bluePen.fillOval(120+7*t,(int)(1.0/2*t*9.8),15,15); try{ blue.sleep(40); }catch(InterruptedException?e){} } } } }