Interface GraphIfc<V>

public interface GraphIfc<V>

An interface describing a Graph object. The graph can be either directed or undirected.

Author:

alchambers

Method Summary

Modifier and Type	Method and Description
void	addEdge(V u, V v) Adds an edge between vertices u and v in the graph.
void	addVertex(V v) Adds a vertex to the graph.
void	clear() Removes all vertices from the graph
boolean	containsVertex(V v) Determines whether the given vertex is already contained in the graph.
int	degree(V v) Returns the degree of the vertex.
boolean	edgeExists(V v, V u) Determines whether an edge exists between two vertices.
java.util.List<V>	getNeighbors(V v) Returns the neighbors of v in the graph.
java.util.Set<V>	getVertices() Returns the set of all vertices in the graph.
int	numEdges() Returns the number of edges in the graph
int	numVertices() Returns the number of vertices in the graph
java.lang.String	toString() Returns a string representation of the graph.

Method Detail

numVertices

int numVertices()

Returns the number of vertices in the graph

Returns:

The number of vertices in the graph

numEdges

int numEdges()

Returns the number of edges in the graph

Returns:

The number of edges in the graph

clear

void clear()

Removes all vertices from the graph

addVertex

void addVertex(V v)

Adds a vertex to the graph. This method has no effect if the vertex already exists in the graph.

Parameters:

v - The vertex to be added

addEdge

void addEdge(V u,
             V v)

Adds an edge between vertices u and v in the graph.

Parameters:

u - A vertex in the graph

v - A vertex in the graph

Throws:

java.lang.IllegalArgumentException - if either vertex does not occur in the graph.

getVertices

java.util.Set<V> getVertices()

Returns the set of all vertices in the graph.

Returns:

A set containing all vertices in the graph

getNeighbors

java.util.List<V> getNeighbors(V v)

Returns the neighbors of v in the graph. A neighbor is a vertex that is connected to v by an edge. If the graph is directed, this returns the vertices u for which an edge (v, u) exists.

Parameters:

v - An existing node in the graph

Returns:

All neighbors of v in the graph.

Throws:

java.lang.IllegalArgumentException - if the vertex does not occur in the graph

containsVertex

boolean containsVertex(V v)

Determines whether the given vertex is already contained in the graph. The comparison is based on the equals() method in the class V.

Parameters:

v - The vertex to be tested.

Returns:

True if v exists in the graph, false otherwise.

edgeExists

boolean edgeExists(V v,
                   V u)

Determines whether an edge exists between two vertices. In a directed graph, this returns true only if the edge starts at v and ends at u.

Parameters:

v - A node in the graph

u - A node in the graph

Returns:

True if an edge exists between the two vertices

Throws:

java.lang.IllegalArgumentException - if either vertex does not occur in the graph

degree

int degree(V v)

Returns the degree of the vertex. In a directed graph, this returns the outdegree of the vertex.

Parameters:

v - A vertex in the graph

Returns:

The degree of the vertex

Throws:

java.lang.IllegalArgumentException - if the vertex does not occur in the graph

toString

java.lang.String toString()

Returns a string representation of the graph. The string representation shows all vertices and edges in the graph.

Overrides:

toString in class java.lang.Object

Returns:

A string representation of the graph