VertexInterface.java

import java.util.Iterator;
/** An interface for a vertex in a graph. */
public interface VertexInterface<T> {
	
	/** Gets this vertex's label.
	 * @return The object that labels the vertex.
	 */
	public T getLabel();

	/** Marks this vertex as visited. */
	public void visit();

	/** Removes this vertex's visited mark. */
	public void unvisit();

	/** Sees whether the vertex is marked as visited.
	 * @return True if the vertex is visited.
	 */
	public boolean isVisited();


	/** Connects this vertex and a given vertex with a weighted edge.
	 * The two vertices cannot be the same, and must not already have 
	 * this edge between them. In a directed graph, the edge points
	 * towards the given vertex.
	 * @param endVertex A vertex in the graph that ends the edge.
	 * @param edgeWeight A real-value edge weight, if any.
	 * @return True if the edge is added, or false if not.
	 */
	public boolean connect(VertexInterface<T> endVertex, double edgeWeight);

	/** Connects this vertex and given vertex with an unweighted edge.
	 * The two vertices cannot be the same, and must not already have
	 * this edge between them. In a directed graph, the edge points towards the
	 * given vertex.
	 * @param endVertex A vertex in the graph that ends the edge.
	 * @return True if the edge is added, or false if not.
	 */
	public boolean connect(VertexInterface<T> endVertex);

	/** Creates an iterator of this vertex's neighbors by following 
	 * all edges that begin at this vertex.
	 * @return An iterator of the neighboring vertices of this vertex.
	 */
	public Iterator<VertexInterface<T>> getNeighborIterator();

	/** Creates an iterator of the weights of the edges to thisthis
	 * vertex's neighbors.
	 * @return An iterator of edge weights of the edges to this vertex's neighbors.
	 */
	public Iterator<Double> getWeightIterator();

	/** Sees whether this vertex has at least one neighbor.
	 * @return True if the vertex has a neighbor.
	 */
	public boolean hasNeighbor();

	/** Gets an unvisited neighbor, if any, of this vertex.
	 * @return Either a vertex that is an unvisted neighbor or null if no such
	 * neighbor exists.
	 */
	public VertexInterface<T> getUnvistedNeighbor();

	/** Records the previous vertex on a path to this vertex.
	 * @param predecessor The vertex previous to this one along a path.
	 */
	public void setPredecessor(VertexInterface<T> predecessor);

	/** Gets the recorded predecessor of this vertex.
	 * @return Either this vertex's predecessor or null if no predecessor was recorded.
	 */
	public VertexInterface<T> getPredecessor();

	/** Sees whether a predecessor was recorded for this vertex.
	 * @return True if a predecessor was recorded.
	 */
	public boolean hasPredecessor();

	/** Records the cost of a path to this vertex.
	 * @param newCost The cost of the path.
	 */
	public void setCost(double newCost);

	/** Gets the recorded cost of the path to this vertex.
	 * @return The cost of the path.
	 */
	public double getCost(); 

}	// end VertexInterface