Question

求解JAVA编程题:编写一个应用程序,创建三个线程分别显示各自的运行时间

要用Calendar
不好使。。。

Answer 1

public class ThreadRuningTime {
	public static AtomicInteger integer = new AtomicInteger(0);
	public static AtomicInteger s = new AtomicInteger(0);
	public static int threadNum = 3;
	public static void main(String[] args) {

		for (int i = 0; i < threadNum; i++) {
			new Thread(new MyThread()).start();
		}
		
		
		new Thread(new Runnable() {
			public void run() {
				while(true) {
					if (s.get()==threadNum) {
						System.out.println(integer.get());
						break;
					}
				}
			}
		}).start();
	}
	public static class MyThread implements Runnable {
		@Override
		public void run() {
			long startTime = System.currentTimeMillis();
			try {
				Thread.sleep(new Random().nextInt(2000));
			} catch (InterruptedException e) {
				e.printStackTrace();
			}
			for (int i = 0; i < 10000000; i++) {
				integer.incrementAndGet();
			}
			
			System.out.println(Thread.currentThread().getName()+" running time "+(System.currentTimeMillis()-startTime+"ms"));
			s.incrementAndGet();
		}
		
	}
}

Answer 2

用Calendar的话,打印时间的地方就改为Calendar.getInstance().getTime() 

我很奇怪,为什么代码贴不上来?? 图片也插入不了?

Answer 3

import java.util.Calendar;
import java.util.concurrent.locks.Lock;

public class MultiThread {
static Lock mylock;
public static void main(String[] args) {
RunningObject1 r1 = new RunningObject1();

Thread t1 = new Thread(r1, "t1");
Thread t2 = new Thread(r1, "t2");
Thread t3 = new Thread(r1, "t3");
t1.start();
t3.start();
t2.start();
}

static class RunningObject1 implements Runnable {
public void run() {
synchronized(this){
String name=Thread.currentThread().getName();
System.out.println(name+"开始时间:"+Calendar.getInstance().getTimeInMillis());

for (int i = 0; i < 100000000; i++) {
if (i == 9999999) {
System.out.println(name+"结束时间:"+Calendar.getInstance().getTimeInMillis());
break;
}
}
}
}
}

}

Answer 4

public class ThreadE{
class Thread2 implements Runnable{
public void run(){
System.out.println(Thread.currentThread().getName()+" run "+Calendar.getInstance().getTime());
}
}

public static void main(String[] args) {
ThreadE te = new ThreadE();
new Thread(te.new Thread2()).start();
new Thread(te.new Thread2()).start();
new Thread(te.new Thread2()).start();
}
}

Answer 5

import java.util.Calendar;

public class MyThread implements Runnable{

String name;

public MyThread(String name){

this.name = name;

}

@Override

public void run() {

Calendar time1  = Calendar.getInstance();

long t1 = time1.getTimeInMillis();

/*---------------------

线程体

-----------------------------------*/

Calendar time2  = Calendar.getInstance();

long t2 = time2.getTimeInMillis();

System.out.println("线程"+name+"运行时间为:"+(t2-t1)+"毫秒");

}

}