thread

 /*************************************************
* Semaphore Class implemented using synchronized *
* & the system calls wait() & notify()           *
* ============================================== *
* Name: Nantipat Tullwattana                     *
* Major: B.Sc. of Software Engineering           *
*************************************************/
public class Semaphore
{

    public Semaphore(int i){ value=i;}
    /*Wait() implemented as synchronized to ensure that it is done atomically*/
    public synchronized void Wait()
    {
        /*decremnt the semaphore*/
        value--;
        /*force the process to wait if value<0 */
        if(value<0)
            wait();
    }
    /*Signal() is implemented as synchronized to ensure it is done atomically*/
    public synchronized void Signal()
    {
        value++; /* increment semaphore value*/
        /*wake up any waiting processes*/
        if(value<=0)
            notify();
    }
}