mutex.java

package SPOS;
public class mutex {
    public final static int NUMTHREADS = 3;
    public static int sharedData = 0;
    public static int sharedData2 = 0;

    static class theLock extends Object{
    }

    static public theLock lockObject = new theLock();

    static class theThread extends Thread 
    {
        public void run()
        {
            System.out.print("Thread " + getName() + ": Entered\n");
            synchronized (lockObject)
            {
                /********** Critical Section *******************/
                System.out.println("Thread " + getName() + ": Start critical section, in synchronized block\n");
                ++sharedData;
                --sharedData2;
                System.out.print("Thread " + getName() + ": End critical section, leave synchronized block\n");
                /********** Critical Section *******************/
            }
        }
    }

    public static void main(String argv[]) {
        theThread threads[] = new theThread[NUMTHREADS];
        System.out.print("Entered the testcase\n");
        System.out.print("Synchronize to prevent access to shared data\n");
        synchronized (lockObject)
        {
        	System.out.print("Create/start the thread\n");
            for (int i = 0; i < NUMTHREADS; ++i)
            {
                threads[i] = new theThread();
                threads[i].start();
            }
            System.out.print("Wait a bit until we're 'done' with the shared data\n");
            try
            {
                Thread.sleep(3000);
            }
            catch (InterruptedException e){
                System.out.print("sleep interrupted\n");
            }
            System.out.print("Unlock shared data\n");
        }
        System.out.print("Wait for the threads to complete\n");
        try
        {
            for (int i = 0; i < NUMTHREADS; ++i)
            {
                threads[i].join();
                System.out.print("Testcase completed\n");
                System.exit(0);
            }
        }
        catch (InterruptedException e)
        {
            System.out.print("Join interrupted\n");
        }
    }
}