structure
Interface Graph

All Superinterfaces:

Structure

All Known Implementing Classes:

GraphList, GraphListDirected, GraphListUndirected, GraphMatrix, GraphMatrixDirected, GraphMatrixUndirected

public interface Graph
extends Structure

The interface describing all Graph objects. Graphs are collections of vertices connected by a set of edges. Edges may or may not be directed. Portions of the graph may be marked visited to support iterative algorithms. Iteration is provided over vertices, edges, and vertices adjacent to a particular vertex

See Also:

GraphList, GraphMatrix

Method Summary

void	add(Object label) Add a vertex to the graph
void	addEdge(Object vtx1, Object vtx2, Object label) Add an edge between two vertices within the graph.
void	clear() Remove all vertices (and thus, edges) of the graph.
boolean	contains(Object label) Test for vertex membership.
boolean	containsEdge(Object vLabel1, Object vLabel2) Test for edge membership.
int	degree(Object label) Determine out degree of vertex.
int	edgeCount() Determine the number of edges in graph.
Iterator	edges() Construct an iterator over all edges.
Object	get(Object label) Get reference to actual label of vertex.
Edge	getEdge(Object label1, Object label2) Get reference to actual edge.
boolean	isDirected() Determine if graph is directed.
boolean	isEmpty() Determine if graph is empty.
boolean	isVisited(Object label) Return visited flag of vertex.
boolean	isVisitedEdge(Edge e) Return visited flag of edge.
Iterator	iterator() Construct vertex iterator.
Iterator	neighbors(Object label) Construct an adjacent vertex iterator.
Object	remove(Object label) Remove a vertex from the graph.
Object	removeEdge(Object vLabel1, Object vLabel2) Remove possible edge between vertices labeled vLabel1 and vLabel2.
void	reset() Clear visited flags of edges and vertices.
int	size() Determine number of vertices within graph.
boolean	visit(Object label) Test and set visited flag of vertex
boolean	visitEdge(Edge e) Test and set visited flag of edge.

Methods inherited from interface structure.Structure

elements, values

Method Detail

add

void add(Object label)

Add a vertex to the graph

Specified by:

add in interface Structure

Parameters:

label - Label of the vertex; should be non-null

addEdge

void addEdge(Object vtx1,
             Object vtx2,
             Object label)

Add an edge between two vertices within the graph. Edge is directed iff graph is directed. Duplicate edges are silently replaced. Labels on edges may be null.

Parameters:

vtx1 - First (or source, if directed) vertex.

vtx2 - Second (or destination, if directed) vertex.

label - Label associated with the edge.

remove

Object remove(Object label)

Remove a vertex from the graph. Associated edges are also removed. Non-vertices are silently ignored.

Specified by:

remove in interface Structure

Parameters:

label - The label of the vertex within the graph.

Returns:

The label associated with the vertex.

removeEdge

Object removeEdge(Object vLabel1,
                  Object vLabel2)

Remove possible edge between vertices labeled vLabel1 and vLabel2. Directed edges consider vLabel1 to be the source.

Parameters:

vLabel1 - First (or source, if directed) vertex.

vLabel2 - Second (or destination, if directed) vertex.

Returns:

The label associated with the edge removed.

get

Object get(Object label)

Get reference to actual label of vertex. Vertex labels are matched using their equals method, which may or may not test for actual equivalence. Result remains part of graph.

Parameters:

label - The label of the vertex sought.

Returns:

The actual label, or null if none is found.

getEdge

Edge getEdge(Object label1,
             Object label2)

Get reference to actual edge. Edge is identified by the labels on associated vertices. If edge is directed, the label1 indicates source.

Parameters:

label1 - The first (or source, if directed) vertex.

label2 - The second (or destination, if directed) vertex.

Returns:

The edge, if found, or null.

contains

boolean contains(Object label)

Test for vertex membership.

Specified by:

contains in interface Structure

Parameters:

label - The label of the vertex sought.

Returns:

True iff vertex with matching label is found.

containsEdge

boolean containsEdge(Object vLabel1,
                     Object vLabel2)

Test for edge membership. If edges are directed, vLabel1 indicates source.

Parameters:

vLabel1 - First (or source, if directed) vertex.

vLabel2 - Second (or destination, if directed) vertex.

Returns:

True iff the edge exists within the graph.

visit

boolean visit(Object label)

Test and set visited flag of vertex

Parameters:

label - Label of vertex to be visited.

Returns:

Previous value of visited flag on vertex.

visitEdge

boolean visitEdge(Edge e)

Test and set visited flag of edge.

Parameters:

e - Edge object that is part of graph.

Returns:

Previous value of the Edge's visited flag.

isVisited

boolean isVisited(Object label)

Return visited flag of vertex.

Parameters:

label - Label of vertex.

Returns:

True if vertex has been visited.

isVisitedEdge

boolean isVisitedEdge(Edge e)

Return visited flag of edge.

Parameters:

e - Edge of graph to be considered.

Returns:

True if the edge has been visited.

reset

void reset()

Clear visited flags of edges and vertices.

size

int size()

Determine number of vertices within graph.

Specified by:

size in interface Structure

Returns:

The number of vertices within graph.

degree

int degree(Object label)

Determine out degree of vertex.

Parameters:

label - Label associated with vertex.

Returns:

The number of edges with this vertex as source.

edgeCount

int edgeCount()

Determine the number of edges in graph.

Returns:

Number of edges in graph.

iterator

Iterator iterator()

Construct vertex iterator. Vertices are not visited in any guaranteed order.

Specified by:

iterator in interface Structure

Returns:

Iterator traversing vertices in graph.

See Also:

AbstractIterator, Iterator, Enumeration, Structure.elements()

neighbors

Iterator neighbors(Object label)

Construct an adjacent vertex iterator. Adjacent vertices (those on destination of edge, if directed) are considered, but not in any guaranteed order.

Parameters:

label - Label of the vertex.

Returns:

Iterator traversing the adjacent vertices of labeled vertex.

edges

Iterator edges()

Construct an iterator over all edges. Every directed/undirected edge is considered exactly once. Order is not guaranteed.

Returns:

Iterator over edges.

clear

void clear()

Remove all vertices (and thus, edges) of the graph.

Specified by:

clear in interface Structure

isEmpty

boolean isEmpty()

Determine if graph is empty.

Specified by:

isEmpty in interface Structure

Returns:

True iff there are no vertices in graph.

isDirected

boolean isDirected()

Determine if graph is directed.

Returns:

True iff the graph is directed.