我有以下类(class)
class ThreadDemo extends Thread {
private Thread t;
private String threadName;
ThreadDemo( String name) {
threadName = name;
}
public void run() {
for(int i = 5; i > 0; i--) {
System.out.println("Thread " + threadName + " Counter --- " + i );
}
try {
Thread.sleep(1000);
} catch (Exception e) {
System.out.println("Sleep issue");
}
System.out.println("Finishing run");
try {
Thread.sleep(1000);
} catch (Exception e) {
System.out.println("Sleep issue");
}
}
public void start () {
t = new Thread (this, threadName);
t.start ();
}
}
测试如下
public class Main {
public static void main(String[] args) {
ThreadDemo T1 = new ThreadDemo( "Thread - 1 ");
ThreadDemo T2 = new ThreadDemo( "Thread - 2 ");
T1.start();
T2.start();
//Let's give some time for threads to run
try {
Thread.sleep(10);
} catch (Exception e) {
System.out.println("Main sleep issue");
}
try {
T1.join();
T2.join();
} catch ( Exception e) {
System.out.println("Interrupted");
}
System.out.println("Finishing main.");
}
}
为什么我总是在输出中的“Finishing run”之前得到“Finishing main”,尽管我使用了 T1.join() 和 T2.join() 来等待它们完成?最初我认为这可能是由于缓冲区延迟造成的,所以我在 run() 末尾添加了 Thread.sleep(1000) 以给一些时间来打印“Finishing run”,但它没有帮助。我猜这是由于第一次出现 Thread.sleep(1000) (当我删除它时,它工作正常),但不知道为什么。
最佳答案
是因为这个:
public void start () {
t = new Thread (this, threadName);
t.start ();
}
因此,您的 ThreadDemo
实例实际上从未作为线程启动:打印 Finishing run
消息的线程是在该方法中创建的线程。该线程和 ThreadDemo 之间没有链接。
删除 start()
方法。
关于java Thread.join 未按预期工作,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/47443975/