com.google.common.graph

Class AbstractGraph<N>

java.lang.Object

com.google.common.graph.AbstractGraph<N>

Type Parameters:

N - Node parameter type

All Implemented Interfaces:

Graph<N>

Direct Known Subclasses:

ImmutableGraph

@Beta
public abstract class AbstractGraph<N>
extends Object
implements Graph<N>

This class provides a skeletal implementation of Graph. It is recommended to extend this class rather than implement Graph directly.

Since:

20.0

Author:

James Sexton

Constructor Summary

Constructors

Constructor and Description
AbstractGraph()

Method Summary

Modifier and Type	Method and Description
int	degree(N node) Returns the count of node's incident edges, counting self-loops twice (equivalently, the number of times an edge touches node).
protected long	edgeCount() Returns the number of edges in this graph; used to calculate the size of edges().
Set<EndpointPair<N>>	edges() An implementation of BaseGraph.edges() defined in terms of nodes() and successors(Object).
boolean	equals(Object obj) Returns true iff object is a Graph that has the same elements and the same structural relationships as those in this graph.
boolean	hasEdgeConnecting(N nodeU, N nodeV) Returns true if there is an edge directly connecting nodeU to nodeV.
int	hashCode() Returns the hash code for this graph.
int	inDegree(N node) Returns the count of node's incoming edges (equal to predecessors(node).size()) in a directed graph.
int	outDegree(N node) Returns the count of node's outgoing edges (equal to successors(node).size()) in a directed graph.
String	toString() Returns a string representation of this graph.

Methods inherited from class java.lang.Object

clone, finalize, getClass, notify, notifyAll, wait, wait, wait

Methods inherited from interface com.google.common.graph.Graph

adjacentNodes, allowsSelfLoops, degree, edges, hasEdgeConnecting, inDegree, isDirected, nodeOrder, nodes, outDegree, predecessors, successors

Constructor Detail

AbstractGraph

public AbstractGraph()

Method Detail

equals

public final boolean equals(@Nullable
                            Object obj)

Description copied from interface: Graph

Returns true iff object is a Graph that has the same elements and the same structural relationships as those in this graph.

Thus, two graphs A and B are equal if all of the following are true:

• A and B have equal directedness.
• A and B have equal node sets.
• A and B have equal edge sets.

Graph properties besides directedness do not affect equality. For example, two graphs may be considered equal even if one allows self-loops and the other doesn't. Additionally, the order in which nodes or edges are added to the graph, and the order in which they are iterated over, are irrelevant.

A reference implementation of this is provided by equals(Object).

Specified by:

equals in interface Graph<N>

Overrides:

equals in class Object

hashCode

public final int hashCode()

Description copied from interface: Graph

Returns the hash code for this graph. The hash code of a graph is defined as the hash code of the set returned by Graph.edges().

A reference implementation of this is provided by hashCode().

Specified by:

hashCode in interface Graph<N>

Overrides:

hashCode in class Object

toString

public String toString()

Returns a string representation of this graph.

Overrides:

toString in class Object

edgeCount

protected long edgeCount()

Returns the number of edges in this graph; used to calculate the size of edges(). This implementation requires O(|N|) time. Classes extending this one may manually keep track of the number of edges as the graph is updated, and override this method for better performance.

edges

public Set<EndpointPair<N>> edges()

An implementation of BaseGraph.edges() defined in terms of nodes() and successors(Object).

degree

public int degree(N node)

Returns the count of node's incident edges, counting self-loops twice (equivalently, the number of times an edge touches node).

For directed graphs, this is equal to inDegree(node) + outDegree(node).

For undirected graphs, this is equal to adjacentNodes(node).size() + (1 if node has an incident self-loop, 0 otherwise).

If the count is greater than Integer.MAX_VALUE, returns Integer.MAX_VALUE.

inDegree

public int inDegree(N node)

Returns the count of node's incoming edges (equal to predecessors(node).size()) in a directed graph. In an undirected graph, returns the degree(Object).

If the count is greater than Integer.MAX_VALUE, returns Integer.MAX_VALUE.

outDegree

public int outDegree(N node)

Returns the count of node's outgoing edges (equal to successors(node).size()) in a directed graph. In an undirected graph, returns the degree(Object).

If the count is greater than Integer.MAX_VALUE, returns Integer.MAX_VALUE.

hasEdgeConnecting

public boolean hasEdgeConnecting(N nodeU,
                                 N nodeV)

Returns true if there is an edge directly connecting nodeU to nodeV. This is equivalent to nodes().contains(nodeU) && successors(nodeU).contains(nodeV).

In an undirected graph, this is equal to hasEdgeConnecting(nodeV, nodeU).