第 9 章 多线程与 Applet//例程 9-1：Pi.java/*演示采用多线程技术计算圆周率*/public class Pi{ public static void main(String[] args){ PiCaculator pc = new PiCaculator(); Thread t = new Thread(pc); t.start(); try{ Thread.sleep (10000); //休眠，等待可能出现的异常情况 t.interrupt(); }catch(InterruptedException e){ e.printStackTrace(); } }}class PiCaculator implements Runnable{ private double latestPiEstimate; public void run(){ try{ System.out.print ("Math.PI = "+Math.PI+ "\t" ); calPi(0.00001); System.out.println ("the latestPI = "+this.latestPiEstimate ); }catch(InterruptedException e){ System.out.println("Thecaculator is Interrupted."); } } /**用于计算圆周率的方法，accuracy 为计算精度*/ private void calPi(double accuracy) throws InterruptedException { this.latestPiEstimate =0.0; long iteration= 0; intsign = -1; //按给定精度计算圆周率 while(Math.abs (Math.PI-this.latestPiEstimate)>accuracy){ if(Thread.interrupted ()) throw new InterruptedException(); iteration++; sign = -sign; this.latestPiEstimate += (sign*4.0/(2*iteration-1)); } }}//例程 9-2：SynDemo.java/*演示没有进行线程同步所带来的问题*/public class SynDemo{ public static void main(String[] args){ Demostrator shareDemostrator = new Demostrator(); Thread t1 = new Thread(shareDemostrator,"t1"); Thread t2 = new Thread(shareDemostrator,"t2"); t1.start(); t2.start(); }}class Demostrator implements Runnable{ private int shareData = 0; public void run(){ Thread t = Thread.currentThread (); for(int i = 1; i <= 5; i++){ int copy = shareData; try{ Thread.sleep ((int)(Math.random ()*1000)); }catch(Exception e){ e.printStackTrace(); } System.out.println ("Thread "+t.getName ()+": copy="+copy+"\tshareData="+shareData); shareData++; } }}//例程 9-3：DeadLockDemo.javapublic class DeadLockDemo{ public static void main(String[] args){ DemoObject a = new...
