Top Description Methods
com.google.common.graph

public Interface Network<N, E>

extends SuccessorsFunction<N>, PredecessorsFunction<N>
Known Direct Subinterfaces
com.google.common.graph.MutableNetwork
Known Direct Implementers
com.google.common.graph.AbstractNetwork
Annotations
@Beta
@DoNotMock:Use NetworkBuilder to create a real instance
@ElementTypesAreNonnullByDefault
Type Parameters
<N>
Node parameter type
<E>
Edge parameter type
Imports
com.google.common.annotations.Beta, com.google.errorprone.annotations.DoNotMock, java.util.Optional, .Set, javax.annotation.CheckForNull
An interface for graph-structured data, whose edges are unique objects.

A graph is composed of a set of nodes and a set of edges connecting pairs of nodes.

There are three primary interfaces provided to represent graphs. In order of increasing complexity they are: Graph, ValueGraph, and Network. You should generally prefer the simplest interface that satisfies your use case. See the "Choosing the right graph type" section of the Guava User Guide for more details.

Capabilities

Network supports the following use cases (definitions of terms):

Building a Network

The implementation classes that common.graph provides are not public, by design. To create an instance of one of the built-in implementations of Network, use the NetworkBuilder class: 

MutableNetwork<Integer, MyEdge> graph = NetworkBuilder.directed().build();

NetworkBuilder#build() returns an instance of MutableNetwork, which is a subtype of Network that provides methods for adding and removing nodes and edges. If you do not need to mutate a graph (e.g. if you write a method than runs a read-only algorithm on the graph), you should use the non-mutating Network interface, or an ImmutableNetwork.

You can create an immutable copy of an existing Network using ImmutableNetwork#copyOf(Network): 

ImmutableNetwork<Integer, MyEdge> immutableGraph = ImmutableNetwork.copyOf(graph);

Instances of ImmutableNetwork do not implement MutableNetwork (obviously!) and are contractually guaranteed to be unmodifiable and thread-safe.

The Guava User Guide has more information on (and examples of) building graphs.

Additional documentation

See the Guava User Guide for the common.graph package ("Graphs Explained") for additional documentation, including:

Authors
James Sexton, Joshua O'Madadhain
Since
20.0

Method Summary

Modifier and TypeMethod and Description
public Set<E>
adjacentEdges(E edge)

Returns the edges which have an incident node in common with edge.

public Set<N>
adjacentNodes(N node)

Returns the nodes which have an incident edge in common with node in this network.

public boolean
allowsParallelEdges()

Returns true if this network allows parallel edges.

public boolean
allowsSelfLoops()

Returns true if this network allows self-loops (edges that connect a node to itself).

public Graph<N>
asGraph()

Returns a live view of this network as a Graph.

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).

public Optional<E>
edgeConnecting(N nodeU, N nodeV)

Returns the single edge that directly connects nodeU to nodeV, if one is present, or Optional.empty() if no such edge exists.

public Optional<E>
edgeConnecting(EndpointPair<N> endpoints)

Returns the single edge that directly connects endpoints (in the order, if any, specified by endpoints), if one is present, or Optional.empty() if no such edge exists.

public E
edgeConnectingOrNull(N nodeU, N nodeV)

Returns the single edge that directly connects nodeU to nodeV, if one is present, or null if no such edge exists.

public E
edgeConnectingOrNull(EndpointPair<N> endpoints)

Returns the single edge that directly connects endpoints (in the order, if any, specified by endpoints), if one is present, or null if no such edge exists.

public ElementOrder<E>
edgeOrder()

Returns the order of iteration for the elements of edges().

public Set<E>
edges()

Returns all edges in this network, in the order specified by edgeOrder().

public Set<E>
edgesConnecting(N nodeU, N nodeV)

Returns the set of edges that each directly connect nodeU to nodeV.

public Set<E>
edgesConnecting(EndpointPair<N> endpoints)

Returns the set of edges that each directly connect endpoints (in the order, if any, specified by endpoints).

public boolean
equals(Object object)

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

public boolean
hasEdgeConnecting(N nodeU, N nodeV)

Returns true if there is an edge that directly connects nodeU to nodeV.

public boolean
hasEdgeConnecting(EndpointPair<N> endpoints)

Returns true if there is an edge that directly connects endpoints (in the order, if any, specified by endpoints).

public int
hashCode()

Returns the hash code for this network.

public Set<E>
incidentEdges(N node)

Returns the edges whose incident nodes in this network include node.

public EndpointPair<N>
incidentNodes(E edge)

Returns the nodes which are the endpoints of edge in this network.

public int
inDegree(N node)

Returns the count of node's incoming edges in a directed network.

public Set<E>
inEdges(N node)

Returns all edges in this network which can be traversed in the direction (if any) of the edge to end at node.

public boolean
isDirected()

Returns true if the edges in this network are directed.

public ElementOrder<N>
nodeOrder()

Returns the order of iteration for the elements of nodes().

public Set<N>
nodes()

Returns all nodes in this network, in the order specified by nodeOrder().

public int
outDegree(N node)

Returns the count of node's outgoing edges in a directed network.

public Set<E>
outEdges(N node)

Returns all edges in this network which can be traversed in the direction (if any) of the edge starting from node.

public Set<N>
predecessors(N node)

Redeclares com.google.common.graph.PredecessorsFunction.predecessors.

Returns all nodes in this network adjacent to node which can be reached by traversing node's incoming edges against the direction (if any) of the edge.
public Set<N>
successors(N node)

Redeclares com.google.common.graph.SuccessorsFunction.successors.

Returns all nodes in this network adjacent to node which can be reached by traversing node's outgoing edges in the direction (if any) of the edge.

Method Detail

adjacentEdgesback to summary
public Set<E> adjacentEdges(E edge)

Returns the edges which have an incident node in common with edge. An edge is not considered adjacent to itself.

Exceptions
IllegalArgumentException:
if edge is not an element of this network
adjacentNodesback to summary
public Set<N> adjacentNodes(N node)

Returns the nodes which have an incident edge in common with node in this network.

This is equal to the union of predecessors(Object) and successors(Object).

Exceptions
IllegalArgumentException:
if node is not an element of this network
allowsParallelEdgesback to summary
public boolean allowsParallelEdges()

Returns true if this network allows parallel edges. Attempting to add a parallel edge to a network that does not allow them will throw an IllegalArgumentException.

allowsSelfLoopsback to summary
public boolean allowsSelfLoops()

Returns true if this network allows self-loops (edges that connect a node to itself). Attempting to add a self-loop to a network that does not allow them will throw an IllegalArgumentException.

asGraphback to summary
public Graph<N> asGraph()

Returns a live view of this network as a Graph. The resulting Graph will have an edge connecting node A to node B if this Network has an edge connecting A to B.

If this network allows parallel edges, parallel edges will be treated as if collapsed into a single edge. For example, the degree(Object) of a node in the Graph view may be less than the degree of the same node in this Network.

degreeback to summary
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 networks, this is equal to inDegree(node) + outDegree(node).

For undirected networks, this is equal to incidentEdges(node).size() + (number of self-loops incident to node).

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

Exceptions
IllegalArgumentException:
if node is not an element of this network
edgeConnectingback to summary
public Optional<E> edgeConnecting(N nodeU, N nodeV)

Returns the single edge that directly connects nodeU to nodeV, if one is present, or Optional.empty() if no such edge exists.

In an undirected network, this is equal to edgeConnecting(nodeV, nodeU).

Exceptions
IllegalArgumentException:
  • if there are multiple parallel edges connecting nodeU to nodeV
  • if nodeU or nodeV is not an element of this network
Since
23.0
edgeConnectingback to summary
public Optional<E> edgeConnecting(EndpointPair<N> endpoints)

Returns the single edge that directly connects endpoints (in the order, if any, specified by endpoints), if one is present, or Optional.empty() if no such edge exists.

If this graph is directed, the endpoints must be ordered.

Exceptions
IllegalArgumentException:
  • if there are multiple parallel edges connecting nodeU to nodeV
  • if either endpoint is not an element of this network
  • if the endpoints are unordered and the graph is directed
Since
27.1
edgeConnectingOrNullback to summary
public E edgeConnectingOrNull(N nodeU, N nodeV)

Returns the single edge that directly connects nodeU to nodeV, if one is present, or null if no such edge exists.

In an undirected network, this is equal to edgeConnectingOrNull(nodeV, nodeU).

Annotations
@CheckForNull
Exceptions
IllegalArgumentException:
  • if there are multiple parallel edges connecting nodeU to nodeV
  • if nodeU or nodeV is not an element of this network
Since
23.0
edgeConnectingOrNullback to summary
public E edgeConnectingOrNull(EndpointPair<N> endpoints)

Returns the single edge that directly connects endpoints (in the order, if any, specified by endpoints), if one is present, or null if no such edge exists.

If this graph is directed, the endpoints must be ordered.

Annotations
@CheckForNull
Exceptions
IllegalArgumentException:
  • if there are multiple parallel edges connecting nodeU to nodeV
  • if either endpoint is not an element of this network
  • if the endpoints are unordered and the graph is directed
Since
27.1
edgeOrderback to summary
public ElementOrder<E> edgeOrder()

Returns the order of iteration for the elements of edges().

edgesback to summary
public Set<E> edges()

Returns all edges in this network, in the order specified by edgeOrder().

edgesConnectingback to summary
public Set<E> edgesConnecting(N nodeU, N nodeV)

Returns the set of edges that each directly connect nodeU to nodeV.

In an undirected network, this is equal to edgesConnecting(nodeV, nodeU).

The resulting set of edges will be parallel (i.e. have equal incidentNodes(Object)). If this network does not allow parallel edges, the resulting set will contain at most one edge (equivalent to edgeConnecting(nodeU, nodeV).asSet()).

Exceptions
IllegalArgumentException:
if nodeU or nodeV is not an element of this network
edgesConnectingback to summary
public Set<E> edgesConnecting(EndpointPair<N> endpoints)

Returns the set of edges that each directly connect endpoints (in the order, if any, specified by endpoints).

The resulting set of edges will be parallel (i.e. have equal incidentNodes(Object)). If this network does not allow parallel edges, the resulting set will contain at most one edge (equivalent to edgeConnecting(endpoints).asSet()).

If this network is directed, endpoints must be ordered.

Exceptions
IllegalArgumentException:
  • if either endpoint is not an element of this network
  • if the endpoints are unordered and the graph is directed
Since
27.1
equalsback to summary
public boolean equals(Object object)

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

Thus, two networks 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.
  • Every edge in A and B connects the same nodes in the same direction (if any).

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

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

Annotations
@Override
hasEdgeConnectingback to summary
public boolean hasEdgeConnecting(N nodeU, N nodeV)

Returns true if there is an edge that directly connects nodeU to nodeV. This is equivalent to nodes().contains(nodeU) && successors(nodeU).contains(nodeV), and to edgeConnectingOrNull(nodeU, nodeV) != null.

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

Since
23.0
hasEdgeConnectingback to summary
public boolean hasEdgeConnecting(EndpointPair<N> endpoints)

Returns true if there is an edge that directly connects endpoints (in the order, if any, specified by endpoints).

Unlike the other EndpointPair-accepting methods, this method does not throw if the endpoints are unordered and the graph is directed; it simply returns false. This is for consistency with Graph#hasEdgeConnecting(EndpointPair) and ValueGraph#hasEdgeConnecting(EndpointPair).

Since
27.1
hashCodeback to summary
public int hashCode()

Returns the hash code for this network. The hash code of a network is defined as the hash code of a map from each of its edges to their incident nodes.

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

Annotations
@Override
incidentEdgesback to summary
public Set<E> incidentEdges(N node)

Returns the edges whose incident nodes in this network include node.

This is equal to the union of inEdges(Object) and outEdges(Object).

Exceptions
IllegalArgumentException:
if node is not an element of this network
incidentNodesback to summary
public EndpointPair<N> incidentNodes(E edge)

Returns the nodes which are the endpoints of edge in this network.

Exceptions
IllegalArgumentException:
if edge is not an element of this network
inDegreeback to summary
public int inDegree(N node)

Returns the count of node's incoming edges in a directed network. In an undirected network, returns the degree(Object).

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

Exceptions
IllegalArgumentException:
if node is not an element of this network
inEdgesback to summary
public Set<E> inEdges(N node)

Returns all edges in this network which can be traversed in the direction (if any) of the edge to end at node.

In a directed network, an incoming edge's EndpointPair#target() equals node.

In an undirected network, this is equivalent to incidentEdges(Object).

Exceptions
IllegalArgumentException:
if node is not an element of this network
isDirectedback to summary
public boolean isDirected()

Returns true if the edges in this network are directed. Directed edges connect a source node to a target node, while undirected edges connect a pair of nodes to each other.

nodeOrderback to summary
public ElementOrder<N> nodeOrder()

Returns the order of iteration for the elements of nodes().

nodesback to summary
public Set<N> nodes()

Returns all nodes in this network, in the order specified by nodeOrder().

outDegreeback to summary
public int outDegree(N node)

Returns the count of node's outgoing edges in a directed network. In an undirected network, returns the degree(Object).

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

Exceptions
IllegalArgumentException:
if node is not an element of this network
outEdgesback to summary
public Set<E> outEdges(N node)

Returns all edges in this network which can be traversed in the direction (if any) of the edge starting from node.

In a directed network, an outgoing edge's EndpointPair#source() equals node.

In an undirected network, this is equivalent to incidentEdges(Object).

Exceptions
IllegalArgumentException:
if node is not an element of this network
predecessorsback to summary
public Set<N> predecessors(N node)

Redeclares com.google.common.graph.PredecessorsFunction.predecessors.

Returns all nodes in this network adjacent to node which can be reached by traversing node's incoming edges against the direction (if any) of the edge.

In an undirected network, this is equivalent to adjacentNodes(Object).

Annotations
@Override
Exceptions
IllegalArgumentException:
if node is not an element of this network
successorsback to summary
public Set<N> successors(N node)

Redeclares com.google.common.graph.SuccessorsFunction.successors.

Returns all nodes in this network adjacent to node which can be reached by traversing node's outgoing edges in the direction (if any) of the edge.

In an undirected network, this is equivalent to adjacentNodes(Object).

This is not the same as "all nodes reachable from node by following outgoing edges". For that functionality, see Graphs#reachableNodes(Graph, Object).

Annotations
@Override
Exceptions
IllegalArgumentException:
if node is not an element of this network