Thread.interrupt 返回 false

Question

I was trying out the below code, I interrupted a user thread, when I print the value of isInterrupted it is returning false, I didn't got a single true value, over here the flag will get reset when the exception has been caught or on calling interrupted method.

Secondly, as per my understanding sleep method should throw and interruptedException in each iteration, the value in catch print, but it is throwing only once.

class ThreadInterruptt extends Thread
{
    public void run()
    {

        for(int i = 0; i<100;i++)
        {
            try {
                Thread.sleep(1000);
                System.out.println(i);
                System.out.println(isInterrupted());
            } catch (InterruptedException e) {
                System.out.println("Thread Interrupted");
            }
        }
    }
}
public class ThreadInterrupt {
    public static void main(String ag[]) throws InterruptedException
    {
        ThreadInterruptt t = new ThreadInterruptt();
        t.start();
        Thread.sleep(100);
        t.interrupt();

    }

}

Answer 1

You wouldn't ever get to the isInterrupted() check if you are interrupted: Thread.sleep() would have thrown an exception, and also it clears the interrupted status of the Thread, as described in the Javadoc .

And you're then discarding the fact the thread was interrupted (because you don't reset the interrupted flag on catching the exception), so it's not interrupted on the next iteration.