Interface Network<N,E>
- Type Parameters:
N
- Node parameter typeE
- Edge parameter type
- All Known Subinterfaces:
MutableNetwork<N,
E>
- All Known Implementing Classes:
AbstractNetwork
,ImmutableNetwork
A graph is composed of a set of nodes and a set of edges connecting pairs of nodes.
There are three main 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):
- directed graphs
- undirected graphs
- graphs that do/don't allow parallel edges
- graphs that do/don't allow self-loops
- graphs whose nodes/edges are insertion-ordered, sorted, or unordered
- graphs whose edges are unique objects
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:
- Since:
- 20.0
-
Method Summary
Modifier and TypeMethodDescriptionadjacentEdges
(Object edge) Returns the edges which have anincident node
in common withedge
.adjacentNodes
(Object node) Returns the nodes which have an incident edge in common withnode
in this network.boolean
Returns true if this network allows parallel edges.boolean
Returns true if this network allows self-loops (edges that connect a node to itself).asGraph()
Returns a live view of this network as aGraph
.int
Returns the count ofnode
'sincident edges
, counting self-loops twice (equivalently, the number of times an edge touchesnode
).Returns the order of iteration for the elements ofedges()
.edges()
Returns all edges in this network, in the order specified byedgeOrder()
.edgesConnecting
(Object nodeU, Object nodeV) Returns the set of edges directly connectingnodeU
tonodeV
.boolean
For the defaultNetwork
implementations, returns true ifthis == object
(reference equality).int
hashCode()
For the defaultNetwork
implementations, returnsSystem.identityHashCode(this)
.incidentEdges
(Object node) Returns the edges whoseincident nodes
in this network includenode
.incidentNodes
(Object edge) Returns the nodes which are the endpoints ofedge
in this network.int
Returns the count ofnode
'sincoming edges
in a directed network.Returns all edges in this network which can be traversed in the direction (if any) of the edge to end atnode
.boolean
Returns true if the edges in this network are directed.Returns the order of iteration for the elements ofnodes()
.nodes()
Returns all nodes in this network, in the order specified bynodeOrder()
.int
Returns the count ofnode
'soutgoing edges
in a directed network.Returns all edges in this network which can be traversed in the direction (if any) of the edge starting fromnode
.predecessors
(Object node) Returns all nodes in this network adjacent tonode
which can be reached by traversingnode
's incoming edges against the direction (if any) of the edge.successors
(Object node) Returns all nodes in this network adjacent tonode
which can be reached by traversingnode
's outgoing edges in the direction (if any) of the edge.
-
Method Details
-
nodes
Returns all nodes in this network, in the order specified bynodeOrder()
. -
edges
Returns all edges in this network, in the order specified byedgeOrder()
. -
asGraph
Returns a live view of this network as aGraph
. The resultingGraph
will have an edge connecting node A to node B if thisNetwork
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, thedegree(Object)
of a node in theGraph
view may be less than the degree of the same node in thisNetwork
. -
isDirected
boolean isDirected()Returns true if the edges in this network are directed. Directed edges connect asource node
to atarget node
, while undirected edges connect a pair of nodes to each other. -
allowsParallelEdges
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 anUnsupportedOperationException
. -
allowsSelfLoops
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 anUnsupportedOperationException
. -
nodeOrder
ElementOrder<N> nodeOrder()Returns the order of iteration for the elements ofnodes()
. -
edgeOrder
ElementOrder<E> edgeOrder()Returns the order of iteration for the elements ofedges()
. -
adjacentNodes
Returns the nodes which have an incident edge in common withnode
in this network.- Throws:
IllegalArgumentException
- ifnode
is not an element of this network
-
predecessors
Returns all nodes in this network adjacent tonode
which can be reached by traversingnode
's incoming edges against the direction (if any) of the edge.In an undirected network, this is equivalent to
adjacentNodes(Object)
.- Throws:
IllegalArgumentException
- ifnode
is not an element of this network
-
successors
Returns all nodes in this network adjacent tonode
which can be reached by traversingnode
'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, seeGraphs.reachableNodes(Graph, Object)
.- Throws:
IllegalArgumentException
- ifnode
is not an element of this network
-
incidentEdges
Returns the edges whoseincident nodes
in this network includenode
.- Throws:
IllegalArgumentException
- ifnode
is not an element of this network
-
inEdges
Returns all edges in this network which can be traversed in the direction (if any) of the edge to end atnode
.In a directed network, an incoming edge's
EndpointPair.target()
equalsnode
.In an undirected network, this is equivalent to
incidentEdges(Object)
.- Throws:
IllegalArgumentException
- ifnode
is not an element of this network
-
outEdges
Returns all edges in this network which can be traversed in the direction (if any) of the edge starting fromnode
.In a directed network, an outgoing edge's
EndpointPair.source()
equalsnode
.In an undirected network, this is equivalent to
incidentEdges(Object)
.- Throws:
IllegalArgumentException
- ifnode
is not an element of this network
-
degree
Returns the count ofnode
'sincident edges
, counting self-loops twice (equivalently, the number of times an edge touchesnode
).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 tonode
).If the count is greater than
Integer.MAX_VALUE
, returnsInteger.MAX_VALUE
.- Throws:
IllegalArgumentException
- ifnode
is not an element of this network
-
inDegree
Returns the count ofnode
'sincoming edges
in a directed network. In an undirected network, returns thedegree(Object)
.If the count is greater than
Integer.MAX_VALUE
, returnsInteger.MAX_VALUE
.- Throws:
IllegalArgumentException
- ifnode
is not an element of this network
-
outDegree
Returns the count ofnode
'soutgoing edges
in a directed network. In an undirected network, returns thedegree(Object)
.If the count is greater than
Integer.MAX_VALUE
, returnsInteger.MAX_VALUE
.- Throws:
IllegalArgumentException
- ifnode
is not an element of this network
-
incidentNodes
Returns the nodes which are the endpoints ofedge
in this network.- Throws:
IllegalArgumentException
- ifedge
is not an element of this network
-
adjacentEdges
Returns the edges which have anincident node
in common withedge
. An edge is not considered adjacent to itself.- Throws:
IllegalArgumentException
- ifedge
is not an element of this network
-
edgesConnecting
Returns the set of edges directly connectingnodeU
tonodeV
.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 notallow parallel edges
, the resulting set will contain at most one edge.- Throws:
IllegalArgumentException
- ifnodeU
ornodeV
is not an element of this network
-
equals
For the defaultNetwork
implementations, returns true ifthis == object
(reference equality). External implementations are free to define this method as they see fit, as long as they satisfy theObject.equals(Object)
contract.To compare two
Network
s based on their contents rather than their references, seeGraphs.equivalent(Network, Network)
. -
hashCode
int hashCode()For the defaultNetwork
implementations, returnsSystem.identityHashCode(this)
. External implementations are free to define this method as they see fit, as long as they satisfy theObject.hashCode()
contract.
-