public void depthFirstTraversal(String source)
	{

		// Getting the index of the source vertex and
		// checking if the vertex really exists
		int sourceIndex = getIndex(source);
		if(sourceIndex == -1)
		{
			System.out.print("In depthFirstTraversal: vertex ");
			System.out.print(source);
			System.out.println(" is missing.");
			return;
		}

		// Defining and initializing the visited array
		boolean[] visited = new boolean[numVertices];
		for(int j = 0; j < numVertices; j++)
			visited[j] = false;	
		visited[sourceIndex] = true;
		
		// Defining and initializing the stack 
		Stack<Integer> s = new Stack<Integer>();
		s.push(new Integer(sourceIndex));

		// The traversal can go on while the stack 
		// contains a vertex to process
		while(!s.empty())
		{
			// Peek at the current vertex
			int currentVertex = (s.peek()).intValue();

			System.out.println(Vertices[currentVertex]);

			// Get the indices of the neighbors of the current vertex
			int[] neighbors = getNeighbors(currentVertex);

			// Scan the neighbors of the current vertex, looking
			// for an unvisited neighbor
			int j = 0;
			boolean found = false;
			while (j < neighbors.length && !found)
			{
				// If an unvisited neighbor has been found,
				// then push it into the stack, mark it visited
				// and get out of the while-loop by setting found
				// to true
				if(!visited[neighbors[j]])	
				{
					s.push(new Integer(neighbors[j]));
					visited[neighbors[j]] = true;
					found = true;
				}

				j++;
			}

			if (!found)
				s.pop();
		} // end of while-stack-not-empty loop

	} // end of function