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));

		// Initializing the depth first traversal tree
		for(int j = 0; j < numVertices; j++)
			dFTTree[j] = j;

		boolean more;
		do
		{
			// 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,
					// make the current vertex its parent,
					// 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;
						dFTTree[neighbors[j]] = currentVertex;
					}

					j++; // scan the next vertex
				}

				// If no unvisited vertices have been found, it is time
				// to backtrack
				if (!found)
					s.pop();
			} // end of while-stack-not-empty loop

			// Determine if there are more unvisited vertices
			// by scanning the visited array and looking for the
			// first unvisited vertex
			more = false;
			int j = 0;
			while(j < numVertices && !more)
			{
				if(!visited[j])
					more = true;
				j++;
			}	

		}
		while(more);

	} // end of function