stopping a thread

[Komal Amaresh]

Sir,

I want to stop a thread. I'm reading "Thinking in java" which says either interrupt() or the static metthod interrupted() would help me leave run() as stop() is deprecated. i'm using it in the code but the thread is not stopping. the code is:

    
public class InterruptDemo implements Runnable{

	int i;
	public void run()
	{
		while(true)
		{
			System.out.println(Thread.currentThread().getName()+" "+ i);
			//i++;
			try{
				
				Thread.sleep(1000);
			}
			catch(Exception e){
				System.out.println(Thread.currentThread().getName()+" interrupted");
			}
			i++;
			if(i == 10)
			{
				try{
					
					Thread.interrupted();
				}
				catch(Exception e){
					System.out.println(Thread.currentThread().getName()+" interrupted");
				}
				finally{
					System.out.println(Thread.currentThread().isAlive());
				}
			}
		}
	}
	public static void main(String[] args) {
		// TODO Auto-generated method stub
		InterruptDemo id = new InterruptDemo();
		Thread t1 = new Thread(id);
		t1.start();
		System.out.println("MAin thread in progress");
		System.out.println("t1 state : "+ t1.isAlive());
		System.out.println("main thread ending...");
	}

}

I don't want to use executors initially.
Can you help me.

Thanks in advance

Komal

[Campbell Ritchie]

Too difficult a question for us beginners. Moving.

[Ulf Dittmer]

You're misunderstanding how interrupt/interrupted works. "interrupt" would generally be called from outside the thread, while the thread would use "interrupted" to check whether "interrupt" has been called. (Note that "interrupted" doesn't do anything - it returns something, which your code currently ignores.)

java.lang.Thread

[Manoj Maniraj]

You can stop like this

  class MyThread extends Thread {
  public boolean stopped = false;

  int count = 0;

  public void run() {
    while (!stopped) {
      try {
        sleep(1000);
      } catch (InterruptedException e) {
      }
      System.out.println(count++);
      ;
    }
  }
}

public class MainClass {

  public static void main(String[] args) {
    MyThread thread = new MyThread();
    thread.start();
    thread.stopped = true;
    System.out.println("exit");
  }

}  

[Jelle Klap]

Ulf Dittmer wrote:Note that "interrupted" doesn't do anything - it returns something, which your code currently ignores.

Well, in addition to returning the interrupted status of the thread the interrupted() method also reset the interrupted status. So if you want to get the interrupted status without resetting it you should use isInterrupted() instead.
A subtle but important distinction.

[Komal Amaresh]

hi manoj,

well, your code works fine. but it exits with no result.

regards,
komal

[Naga Niranjan]

Komal,

Modify your code to implement finite loop instead of infiite loop. Otherwise use break statement instead of using Thread.inrerrupted()

Thanks,
Niranjan

[Komal Amaresh]

I'am able to use a finite loop and stop the thread by a boolean, but the interrupt() as such is not working.
can anybody please help me.
please show how the interrupt works through some code

regards,
Komal

[Sanju Thomas]

change your code to interrupt the current thread.

Thread.currentThread().interrupt();

in the catch block write the logic to break your loop.

[Komal Amaresh]

Thanks Sanju,

i got it. i called a condition in a seperate method and interrupted the thread there and called the method into run where i used an infinite loop. ctecking if the thread is interrupted by thread.interrupted, i used break to exit the run.
but my question still is not answered.

Dittmer had said:
"interrupt" would generally be called from outside the thread

the interrupt whether called from outside is called on the same thread. how can we call it from outside. i would be glad if you can be more elaborate.

thanking you,

with regards,
komal

[Paul Clapham]

You just keep a reference to the Thread, then call the interrupt() method on that reference.

Thread example = new Thread(...);
example.start();

// later...

example.interrupt();

[Walsh graham]

Hi hi,

I'm no expert but shouldn't the stopped variable be declared as volatile to prevent it from being cached in registers?

happy easter

Graham

Manoj Maniraj wrote:You can stop like this

  class MyThread extends Thread {
  public boolean stopped = false;

  int count = 0;

  public void run() {
    while (!stopped) {
      try {
        sleep(1000);
      } catch (InterruptedException e) {
      }
      System.out.println(count++);
      ;
    }
  }
}

public class MainClass {

  public static void main(String[] args) {
    MyThread thread = new MyThread();
    thread.start();
    thread.stopped = true;
    System.out.println("exit");
  }

}  

[Komal Amaresh]

The following is my code. As i have to call the method which calls interrupt() insie run to stop the thread. where is the question of calling it from outside.

    
public class InterruptDemo implements Runnable{
	
	volatile int i;
	//private boolean cancel = false;
	String name;	

	public void stop1()
	{
		if( i == 10)
		{
			Thread.currentThread().interrupt();
		}
	}
	
	public void run()
	{
		while(true)
		{
			
			System.out.println(Thread.currentThread().getName()+" "+ i);
			i++;
			try {
				Thread.sleep(1000);
			} catch (InterruptedException e) {
				// TODO Auto-generated catch block
				e.printStackTrace();
				
			}			
			stop1();
			if(Thread.interrupted())
			{
				System.out.println("Thread stoopped");
				break;
			}
		}			
	}
	
	
	public static void main(String[] args) throws InterruptedException 
	{
		// TODO Auto-generated method stub
		InterruptDemo id = new InterruptDemo();
		Thread t1 = new Thread(id);
		
		t1.start();
		//id.stop1();
		System.out.println("Main thread started");
//		
	}	
}

help me please.

thanks in advance.

komal

[Naga Niranjan]

Komal,

Check my modifications to your code. I think it will solve your problem.

public class InterruptDemo implements Runnable{   
       
    volatile int i;   
    //private boolean cancel = false;   
    String name;       
  
    public void stop1(Thread t)   
    {   
        /*if( i == 10)   
        {   
            Thread.currentThread().interrupt();   
        } */
    	t.interrupt();
    }   
       
    public void run()   
    {   
        while(true)   
        {   
               
            System.out.println(Thread.currentThread().getName()+" "+ i);   
            i++;   
            try {   
                Thread.sleep(1000);   
            } catch (InterruptedException e) {   
                // TODO Auto-generated catch block   
                e.printStackTrace();   
                   
            }              
            //stop1();   
            if(Thread.interrupted())   
            {   
                System.out.println("Thread stoopped");   
                break;   
            }   
        }              
    }   
       
       
    public static void main(String[] args) throws InterruptedException    
    {   
        // TODO Auto-generated method stub   
        InterruptDemo id = new InterruptDemo();   
        Thread t1 = new Thread(id);   
           
        t1.start();  
        Thread.sleep(10000);
        id.stop1(t1);   
        System.out.println("Main thread started");   
//         
    }      
}      

Thanks,
Niranjan

[Komal Amaresh]

Nope Naga, it is not working, seems like after main thread completes its sleeptime, the interrupted exception is being thrown from there. it is being interrupted in the main and the mainthread is exiting.the uaser thread is continuiing the loop after throwing an interrupted exception.

any solution anyone.

Thanks,
komal

[Walsh graham]

Hi,

try putting the break statement in this try/catch. You're testing isInterrupted AFTER its been interrupted... I think...




try {
Thread.sleep(1000);
} catch (InterruptedException e) {
// TODO Auto-generated catch block
e.printStackTrace();
BREAK; // HERE

}


so by the time you get here...

//stop1();
if(Thread.interrupted())
{
System.out.println("Thread stoopped");
break;
}


you're no longer interrupted.

let me know if this helps

Naga Niranjan wrote:Komal,

Check my modifications to your code. I think it will solve your problem.

public class InterruptDemo implements Runnable{   
       
    volatile int i;   
    //private boolean cancel = false;   
    String name;       
  
    public void stop1(Thread t)   
    {   
        /*if( i == 10)   
        {   
            Thread.currentThread().interrupt();   
        } */
    	t.interrupt();
    }   
       
    public void run()   
    {   
        while(true)   
        {   
               
            System.out.println(Thread.currentThread().getName()+" "+ i);   
            i++;   
            try {   
                Thread.sleep(1000);   
            } catch (InterruptedException e) {   
                // TODO Auto-generated catch block   
                e.printStackTrace();   
                   
            }              
            //stop1();   
            if(Thread.interrupted())   
            {   
                System.out.println("Thread stoopped");   
                break;   
            }   
        }              
    }   
       
       
    public static void main(String[] args) throws InterruptedException    
    {   
        // TODO Auto-generated method stub   
        InterruptDemo id = new InterruptDemo();   
        Thread t1 = new Thread(id);   
           
        t1.start();  
        Thread.sleep(10000);
        id.stop1(t1);   
        System.out.println("Main thread started");   
//         
    }      
}      

Thanks,
Niranjan

[Maris Orbidans]

read javadoc before coding !

The interrupted status of the current thread is cleared when this exception is thrown.

    /**	
     * Causes the currently executing thread to sleep (temporarily cease 
     * execution) for the specified number of milliseconds. The thread 
     * does not lose ownership of any monitors.
     *
     * @param      millis   the length of time to sleep in milliseconds.
     * @exception  InterruptedException if another thread has interrupted
     *             the current thread.  The <i>interrupted status</i> of the
     *             current thread is cleared when this exception is thrown.
     * @see        java.lang.Object#notify()
     */
    public static native void sleep(long millis) throws InterruptedException;

[Komal Amaresh]

Hi Warrent,

Thanks loads,
it worked!!

I later used a boolean and flagged the loop in the run. calling the method stop1 with a thread parameter.i called this method in the main putting the stop1 in the main.get it...

boolean cancel = false;

stop1(Thread t){
cancel = true;
}
run(){
//all code here
}
public static void main()
{
//thread obj;

Thread.sleep(10000);

obj.stop1(t1)//t1 is the thread i created and obj my class object.
}

i could resolve it, BUT this is what is wanted.
Thanks loads

regards,
komal

[Walsh graham]

Hi Hi,

delighted your're up and running.


make that boolean flag volatile to be safe. You've nothing to lose except register storage and it could save you a lot of debugging in months to come if somebody modifies/misuses your code. If performance is a huge part of your applications requirements (and I mean HUGE ), then check before making it volatile.

have a nice day

Graham

[Au Yong Jin Yoo]

I have going to implement similar changes in my company, the headache of my situation is in the store procedure/ function have update the same table (it might have same row record but different column). I hope that you have any others advice or better solution for record lock issues ? Hope you can reply. Thanks in advance.