Thread的join方法demo
代码语言：javascript复制/**
* 关于join官方的解释是 Waits for this thread to die. 也就是等待一个线程结束。
*/
public class ThreadJoinTest {
public static void main(String[] args) throws InterruptedException {
long startTimestamp = System.currentTimeMillis();
// 假设有三台机器，开启三个线程。
Thread m1 = new Thread(new CaptureRunnable("M1", 1_000L));
Thread m2 = new Thread(new CaptureRunnable("M2", 2_000L));
Thread m3 = new Thread(new CaptureRunnable("M3", 3_000L));
/**
* 可以看到三个线程还没走完，就提前把时间打印出来了，这个不是我我们想要的效果，那么我们让三个线程join一下试试：
* Save data begin timestamp is 1665222904024, end timestamp is 1665222904025
* Spend time is 1
* M1 completed data capture at timestamp [1665222905026] and successful.
* M2 completed data capture at timestamp [1665222906025] and successful.
* M3 completed data capture at timestamp [1665222907026] and successful.
*/
m1.start();
m2.start();
m3.start();
/**
*
* 打开注释输出：
* M1 completed data capture at timestamp [1665222874569] and successful.
* M2 completed data capture at timestamp [1665222875569] and successful.
* M3 completed data capture at timestamp [1665222876569] and successful.
* Save data begin timestamp is 1665222873568, end timestamp is 1665222876569
* Spend time is 3001
*/
// m1.join();
// m2.join();
// m3.join();
long endTimestamp = System.currentTimeMillis();
System.out.printf("Save data begin timestamp is %s, end timestamp is %sn", startTimestamp, endTimestamp);
System.out.printf("Spend time is %sn", endTimestamp - startTimestamp);
}
/**
* 采集服务器节点的任务。
*/
static class CaptureRunnable implements Runnable {
// 机器节点的名称
private String machineName;
// 采集花费时间
private long spendTime;
public CaptureRunnable(String machineName, long spendTime) {
this.machineName = machineName;
this.spendTime = spendTime;
}
@Override
public void run() {
// do the really capture data.
try {
Thread.sleep(spendTime);
System.out.printf(machineName " completed data capture at timestamp [%s] and successful.n", System.currentTimeMillis());
} catch (InterruptedException e) {
e.printStackTrace();
}
}
public String getResult() {
return machineName " finish.";
}
}
}
