Java多线程中join方法的理解

package com.sss.test;

import java.util.Random;

/**
 * @author Shusheng Shi
 */
public class ThreadJoinTest {
    static class Computer extends Thread {
        private int start;
        private int end;
        private int result;
        private int[] array;

        public Computer(int[] array, int start, int end) {
            this.array=array;
            this.start=start;
            this.end=end;
        }

        @Override
        public void run() {
            for (int i=start; i < end; i++) {
                result+=array[i];
            }

            if (result < 0) {
                result&=Integer.MAX_VALUE;
            }

        }

        public int getResult() {
            return result;

        }
    }

    private final static int COUNTER=10000000;

    public static void main(String[] args) throws InterruptedException {
        int[] array=new int[COUNTER];
        Random random=new Random();
        for (int i=0; i < COUNTER; i++) {
            array[i]=Math.abs( random.nextInt() );
        }
        long start=System.currentTimeMillis();
        Computer c1=new Computer( array, 0, COUNTER );
        Computer c2=new Computer( array, COUNTER / 2, COUNTER );
        c1.start();
        c2.start();
        c1.join();
        c2.join();
        System.out.println( System.currentTimeMillis() - start );
        System.out.println( (c1.getResult() + c2.getResult()) & Integer.MAX_VALUE );
    }
}