谁在抛出InterruptedException？

Question

In the following code, who is throwing the InterruptedException caught at line-(K+1)?

public class Den implements Runnable {

    Object T = new Object(); 

    public void m1() {

        System.out.println("here ..  "); 
        synchronized(T){
            try {
                T.wait();  // line-K
            } catch (InterruptedException ex) {  // line-(K+1)
                System.out.println("An InterruptedException is thrown ");
                ex.printStackTrace();
            }
                System.out.println("here  2"); 
        }    
    } // m1()

    @Override
    public void run() {m1();}

    public static void main (String ...jsdf) {    
        Den H = new Den();
        Thread t1 = new Thread(H);
        t1.start(); 
        t1.interrupt();        // line-W
    }
}

The output of this code is

run:
here ..  
An InterruptedException is thrown 
java.lang.InterruptedException
    at java.lang.Object.wait(Native Method)
here  2
    at java.lang.Object.wait(Object.java:502)
    at prj.Dene.m1(Dene.java:12)
    at prj.Dene.run(Dene.java:22)
    at java.lang.Thread.run(Thread.java:745)
BUILD SUCCESSFUL (total time: 0 seconds)

The stack trace tells that it's the T.wait() method that is throwing it-- as it should be, there's nothing else in the code that throws an InterruptedException .

But then-- interrupt() is called on the thread t1 and t1 is executing the Runnable H as its Thread.target object. How come T is receiving that interrupt? Is the interrupt() on Thread.target invoking in turn the interrupt() -s of objects it is waiting on? Thread.interrupt() is invoking a native Thread.interrupt0() -- can't see these.

TIA.

Answer 1

t1.interrupt(); is obviously the initiation of the interrupt. You may be unaware, but this only "schedules" an interrupt; the target thread (t1) is not necessarily immediately disturbed... InterruptedException only occurs at well defined points so that you can handled this in code.

wait() is one of these well defined points (along w/ sleep() , and some I/O operations).

In your case, the system injects an exception inside the wait() call. Don't put toooooo much into the line number reported.