// CS 1621
// Deadlock example in Java

class shared
{
      private int id;
      private int data;

      public shared(int newdata, int newid)
      {
             data = newdata;
             id = newid;
      }

	public synchronized int getdata()
	{
		try 
		{
			Thread.sleep(1000);
		}
		catch (InterruptedException e) {}    
		System.out.println("About to return data for " + id);
		return data;
	}

	public synchronized void setdata(int newdata)
	{
		try 
		{
			Thread.sleep(1000);
		}
		catch (InterruptedException e) {}    
		System.out.println("About to set data for " + id);
		data = newdata;
	}

	public synchronized void swap(shared rhs)
	{
		System.out.println("Swap called for data " + id);
            
		int temp = rhs.getdata();
		rhs.setdata(getdata());
		setdata(temp);
	}
}



             
public class deadlock implements Runnable 
{
      private shared [] theData;

             
      private Thread firstThread;
      private Thread secondThread;
      
      public deadlock()
      {
             theData = new shared[2];
             theData[0] = new shared(10,0);
             theData[1] = new shared(20,1);

             firstThread = new Thread(this);
             secondThread = new Thread(this);

             firstThread.start();
             secondThread.start();
      }
             
      public void run()
      {
             if (Thread.currentThread() == firstThread)
             {
                   theData[0].swap(theData[1]);
             }
             else
             {
                   theData[1].swap(theData[0]);
             }
      }
      
      public static void main(String [] args)
      {
             deadlock theObject = new deadlock();
      }

}