Thread Ques

[Swati Gupta]

From Jqplus

 class A extends Thread
{
public void run()
{
System.out.println("Starting loop");
while(true){}; 
}
}
public class TestClass 
{
public static void main(String args[]) throws Exception
{
A a = new A();
a.start(); 
Thread.sleep(1000);
a.interrupt();
}
}

What will be the effect of interrupt() method here.
The answer says it will run forever.
I thought due to interrupt() the flag will set to true.
I am really doing very bad in thread ques in mock exams.
[ June 11, 2002: Message edited by: swati gupta ]

[Abhijeet Gholkar]

class A extends Thread
{
public void run()
{
System.out.println("Starting loop");
while(true)
{
if(isInterrupted())
{
System.out.println("Interrupting");
break;
}
}
}
}
public class TestClass
{
public static void main(String args[]) throws Exception
{
A a = new A();
a.start();
Thread.sleep(1000);
a.interrupt();
}
}
Try this code to putoff the thread

[Bonnie Beach-Morin]

If your looking for a reason as to why it will run forever, it's because the interrupted() method doesn't actually do anything other than set a flag variable. The run method of class A never bothers to check the interrupted flag, so it doesn't know it should stop and runs forever.
Another solution would be to do the following

  
class A extends Thread { 
    public void run() { 
        System.out.println("Starting loop"); 
        while(!isInterrupted()) { };
    }
}
public class TestClass  { 
    public static void main(String args[]) throws Exception { 
        A a = new A(); 
        a.start(); 
        Thread.sleep(1000); 
        a.interrupt(); 
    }
}