interrupt() method can kill a thread??

[basha khan]

look this mock question
Which statements regarding the following code are correct?
class A extends Thread{
public void run(){
System.out.println("starting loop");
while(true){};//(1)
System.out.println("ending loop");
}
}
public class TestClass {
public static void main(String asd[]){
A a=new A();
a.start();
Thread.sleep(1000);
a.interrupt();//(2)
}
}
---------------------------------------
answer is
it will run and end cleanly if //(1) is replaced to while(!isInterrupted())

why it is possible?
The user thread is interrupted at (2) it is not stopped
so how the program will quit?
can interrupt method stop a Thread??.
if interrupt can,plz tell me about interrupt() behavior

[R K Singh]

when u interrupt a thread ... interupted thread can take any action .. if it wants to take by checking isInterupted() method..
here in your prog.. if while is changed with
while(!isInterrupted()) then when it will be interrupted then it will return true .. which in turn becomes false(note ! operator).. so loop won't execute any more ...
so thread will end.
CMIW
HIH

[chung lee]

Hi Basha,
Just to add to what Ravish has said, the main method is a thread which spawns the class A thread.
So when the thread A is executing in the
while(!isInterrupted()){}
it is waiting for an interrupt signal from the main thread which sleeps for at least 1000 milliseconds before calling interrupt() on thread A.
chung

[Bob Graffagnino]

I was under the impression that a call to a Thread object's interrupt() method sets a isInterrupted flag to true. If the program never checks the flag, it won't stop.
The funny thing is, neither the Thread class nor the Object class have an isInterrupted field. Anyone care to explain this to me?

[Rob Ross]

Better check your javadocs again. This method is clearly documented!!

public boolean isInterrupted()
Tests whether this thread has been interrupted. The interrupted status of the thread is unaffected by this method.
Returns:
true if this thread has been interrupted; false otherwise.

Rob

[basha khan]

a few questions from myself not pointed the correct target.this is the latest
my questien was not on isInterrupted() method which comes on //(1)
my questien was on interrupt() on // (2)
here is my questien,
----------------------------------------
class A extends Thread{
public void run(){
System.out.println("starting loop");
while(!isInterruted()){}//(1)
System.out.println("ending loop");
}
}
public class TestClass {
public static void main(String asd[]){
A a=new A();
a.start();
Thread.sleep(1000);//(a)
a.interrupt();//(2)
}
}
---------------------------------------
user thread a will start when main thread sleeps(//a)
thread 'a' will enter into run() and check
!isInterrupted(),the condition is true now.
after the sleeping period of main,thread sheduler have two options
opt(1)main thread can enter on run state,which will make thread 'a' interrupted.so thread 'a' not stopped.
opt(2)user thread can continue,it executes an endless loop.so there is no way to terminate.
above two options, the program will not terminate unless the interrupt() method can kill the thread 'a'
my questien is whether interrupt() method can kill a thread??.if so,plz tell me the behavior of interrupt method?.anyone plz..

[chung lee]

Hi Basha,
I think that you're confusing yourself here. Please feel free to correct me if I'm wrong, but the activity of interrupt() does not kill the thread. Threads may only die when the run() method returns (or if someone turns off your computer etc).
As Rob has correctly pointed out, interrupt() will cause an internal state change within the thread and the boolean "interrupt" flag will change from false to true when the thread is interrupted. This has no affect on the current activity of the running thread.
If interrupt() caused the running thread to stop and/or die, you will be faced with alot of problems. See the deprecated methods of stop(), resume() and suspend() for the full explanation.
I hope that helps.
chung

[basha khan]

afterall i understood
thanks to everybody