public List<Edge> incidentEdges(Vertex vertex) {
		ArrayList<Edge> edgeList = null;
		if (graphType == Type.UNDIRECTED) {
			for (EdgeListObject elo : vertex.getIncidenceList()) {
				if (edgeList == null)
					edgeList = new ArrayList<Edge>();
				edgeList.add(elo.getEdge());
			}
		} else {
			List<EdgeListObject> outEdges = vertex.getOutEdges();
			if (outEdges != null) {
				for (EdgeListObject elo : outEdges) {
					if (edgeList == null)
						edgeList = new ArrayList<Edge>();
					edgeList.add(elo.getEdge());
				}
			}
		}
		return edgeList;

	}