使用新的java线程池技术创建固定的线程去完成任务，都完成后计算总时间

package com.wind.ocean.wzhang.ikseg.longseg;

import java.util.ArrayList;

import java.util.List;

import java.util.Random;

import java.util.concurrent.Callable;

import java.util.concurrent.ExecutionException;

import java.util.concurrent.Executors;

import java.util.concurrent.Future;

import java.util.concurrent.ThreadPoolExecutor;

import java.util.concurrent.TimeUnit;

public class FactorialCalculator implements Callable<Integer> {

private int number;

public FactorialCalculator(int number) {

this.number = number;

}

@Override

public Integer call() throws Exception {

int result = 1;

if(number == 0 || number == 1) {

result = 1;

}else{

for(int i = 2; i <= number; i++) {

result *= i;

TimeUnit.MILLISECONDS.sleep(20);

}

}

System.out.printf("%s: %d\n",Thread.currentThread().

getName(),result);

return result;

}

public static void main(String[] args) {

ThreadPoolExecutor execute = (ThreadPoolExecutor) Executors.newFixedThreadPool(3);

List<Future<Integer>> results = new ArrayList<Future<Integer>>();

Random random = new Random();

for(int i = 0; i < 10; i++) {

int number = random.nextInt(20);

FactorialCalculator calcu = new FactorialCalculator(number);

Future<Integer> result = execute.submit(calcu);

results.add(result);

}

do{

System.out.printf("Main: Number of Completed Tasks:%d\n",execute.getCompletedTaskCount());

for (int i=0; i<results.size(); i++) {

Future<Integer> result=results.get(i);

System.out.printf("Main: Task %d: %s\n",i,result.isDone());

}

try {

TimeUnit.MILLISECONDS.sleep(50);

} catch (InterruptedException e) {

e.printStackTrace();

}

}while(execute.getCompletedTaskCount() < results.size());

System.out.printf("Main: Results\n");

for(Future<Integer> fus : results) {

try {

System.out.printf("Main: Task %d: %d\n",1,fus.get());

} catch (InterruptedException e) {

e.printStackTrace();

} catch (ExecutionException e) {

e.printStackTrace();

}

}

execute.shutdown();

}

}