CODEWITHSUNDEEP
javamultithreading
Denys_newbie
Denys_newbie

Reputation: 1160

Didn't get the InterruptedException from the join() method

Why I don't get InterruptedException in the main thread? Here says that it throws InterruptedException - if any thread has interrupted the current thread. So why I don't get caught InterruptedException when I interrupted thread in the run() method?

public class Test
{
    public static void main(String[] args)
    {
        try
        {
            Thread t1 = new Test1();
            t1.start();
            t1.join();
        }
        catch (InterruptedException e)
        {
            System.out.println("exception has been caught");
        }
    }
}

class Test1 extends Thread
{
    public void run()
    {
        // to ensure that ```t1.join``` in the ```main``` thread executed earlier than ```Thread.currentThread().interrupt();```
        for (int i = 0; i < 10_000; i++) {}

        Thread.currentThread().interrupt();
    }
}

Upvotes: 2

Views: 391

Answers (1)

rzwitserloot
rzwitserloot

Reputation: 103273

Thread.currentThread().interrupt()

This is useless: You're interrupting your own thread, there is never any point in doing this. All this does is raise the interrupt flag on your own thread, meaning, the next time your thread executed any method that is declared to throw interruptedexception, it will immediately do so. Thus: pointless.

What you really wanted to do was interrupt the other thread. t1.join() is an operation that will 'sleep' this thread until t1 finishes. This is an interruptable operation: You do that not by interrupting t1, but by interrupting your main thread.

Here is an example:

public class Test
{
    public static void main(String[] args)
    {
        try
        {
            Test1 t1 = new Test1();
            t1.threadToInterrupt = Thread.currentThread();
            t1.start();
            t1.join();
        }
        catch (InterruptedException e)
        {
            System.out.println("exception has been caught");
        }
    }
}

class Test1 extends Thread
{
    Thread threadToInterrupt;
    public void run()
    {
        for (int i = 0; i < 10_000; i++) {}

        threadToInterrupt.interrupt();
    }
}

Upvotes: 2

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