[jelly]

I suspect that the reason your code is crashing is due to the code

Code:

		if (q1 == null){
			q1.add(data);
		}

you test the q1 reference to be null, and having found it is, you then try to use it. I suspect there are two things you need to change, firstly you need to instantiate the Queues,currently you create reference variables ( q1 and q2 ) that are capable of referring to a Queue but you never actually create the Queues. Maybe something like

Code:

	Queue<Integer> q1 = new LinkedList<Integer>();
	Queue<Integer> q2= new LinkedList<Integer>();

also you are getting confused between

Code:

q1 == null

which says that the variable is not currently referencing a Queue and

Code:

q1.peek() == null

which implies the Queue is empty - though there are edge cases where this may not be true, just don't go there yet