Join的使用
目的：当子线程运行结束后，父线程才能再继续运行
/**
* @ClassName ThreadJoinExample
* @projectName: object1
* @author: Zhangmingda
* @description： XXX
* date: 2021/4/24.
*/
public class ThreadJoinExample {
public static void main(String[] args) throws InterruptedException {
Runnable r = new Runnable() {
@Override
public void run() {
String tName = Thread.currentThread().getName();
try {
System.out.println(tName + "开始运行");
Thread.sleep(4000);
System.out.println(tName +"运行结束！");
} catch (InterruptedException e) {
e.printStackTrace();
}
}
};
Thread thread = new Thread(r,"子任务1");
Thread thread2 = new Thread(r,"子任务2");
thread.start();
thread2.start();
thread.join(); //子线程阻塞主线程，待子线程运行结束
thread2.join(); //子线程阻塞主线程，待子线程运行结束
Thread.sleep(1000);
System.out.println("主线程运行结束！");
}
}
不能interrupt中断一个有join()子线程的父线程
/**
* @ClassName ThreadInterruptJoinThread
* @projectName: object1
* @author: Zhangmingda
* @description： XXX
* date: 2021/4/24.
*/
public class ThreadInterruptJoinThread {
public static void main(String[] args) throws InterruptedException {
Thread thread = new Thread("parent"){
@Override
public void run() {
System.out.println(getName() + "开始运行");
Thread thread1 = new Thread("child"){
@Override
public void run() {
System.out.println(getName() + "开始运行");
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(getName() + "运行结束");
}
};
thread1.start();
//thread1.join();
try {
thread1.join();
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println(getName() + "运行结束");
}
};
thread.start();
Thread.sleep(1000);
thread.interrupt();
thread.join();
System.out.println("主线程运行结束");
}
}
如上代码执行结果：join的child子线程还没结束，父线程就被interrupt中断，会导致父线程异常，且不再等待子线程child运行结束。
join(long)：等待指定时间不结束就不等待了
/**
* @ClassName ThreadJoinTime
* @projectName: object1
* @author: Zhangmingda
* @description： XXX
* date: 2021/4/24.
*/
public class ThreadJoinTime {
public static void main(String[] args) throws InterruptedException {
Thread thread = new Thread("child"){
@Override
public void run() {
System.out.println("子线程开始运行");
try {
Thread.sleep(3000);
} catch (InterruptedException e) {
e.printStackTrace();
}
System.out.println("子线程运行结束");
}
};
thread.start();
thread.join(1000);
System.out.println("主线程代码运行结束");
}
}