Java程序设计教程 冶金工业出版社第9章.doc

第9章多线程与Applet
//例程9-1:
/*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);
();
try{
(10000); //休眠,等待可能出现的异常情况
();
}catch(InterruptedException e){
();
}
}
}
class PiCaculator implements Runnable{
private double latestPiEstimate;
public void run(){
try{
(" = "+ + "\t" );
calPi();
("the latest PI = "+ );
}catch(InterruptedException e){
("The caculator 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
{
=;
long iteration = 0;
int sign = -1;
//按给定精度计算圆周率
while( (-)>accuracy){
if( ())
throw new InterruptedException();
iteration++;
sign = -sign;
+= (sign*/(2*iteration-1));
}
}
}
//例程9-2:
/*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");
();
();
}
}
class Demostrator implements Runnable