N
 Node parameter typeE
 Edge parameter type@Beta public interface Network<N,E>
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.
Yes: Go to question 2. No: Use Graph
.
equal
to each other. A common example
where this would not be the case is with weighted graphs.
Yes: Go to question 3. No: Use ValueGraph
.
Yes: Use Network
. No: Go to question 4.
Yes: Use Network
. No: Use ValueGraph
.
Although MutableValueGraph
and MutableNetwork
both require users to provide
objects to associate with edges when adding them, the differentiating factor is that in ValueGraph
s, these objects can be any arbitrary data. Like the values in a Map
, they do
not have to be unique, and can be mutated while in the graph. In a Network
, these objects
serve as keys into the data structure. Like the keys in a Map
, they must be unique, and
cannot be mutated in a way that affects their equals/hashcode or the data structure will become
corrupted.
In all three interfaces, nodes have all the same requirements as keys in a Map
.
All mutation methods live on the subinterface MutableNetwork
. If you do not need to
mutate a network (e.g. if you write a method than runs a readonly algorithm on the network), you
should prefer the nonmutating Network
interface.
We provide an efficient implementation of this interface via NetworkBuilder
. When
using the implementation provided, all collectionreturning methods provide live, unmodifiable
views of the network. In other words, you cannot add an element to the collection, but if an
element is added to the Network
that would affect the collection, the collection will be
updated automatically. This also means that you cannot mutate a Network
in a way that
would affect a collection while iterating over that collection. For example, you cannot remove
either foo
or any successors of foo
from the network while iterating over successors(foo)
(unless you first make a copy of the successors), just as you could not remove
keys from a Map
while iterating over its Map.keySet()
. Behavior in such a case is
undefined, and may result in ConcurrentModificationException
.
Example of use:
MutableNetwork roadNetwork = NetworkBuilder.undirected().build();
roadNetwork.addEdge("Springfield", "Shelbyville", "Monorail");
roadNetwork.addEdge("New York", "New New York", "Applied Cryogenics");
roadNetwork.addEdge("Springfield", "New New York", "Secret Wormhole");
String roadToQuery = "Secret Wormhole";
if (roadNetwork.edges().contains(roadToQuery)) {
EndpointPair cities = roadNetwork.incidentNodes(roadToQuery);
System.out.format("%s and %s connected via %s", cities.nodeU(), cities.nodeV(), roadToQuery);
}
Modifier and Type  Method and Description 

Set<E> 
adjacentEdges(Object edge)
Returns the edges which have an
incident node in common with
edge . 
Set<N> 
adjacentNodes(Object node)
Returns the nodes which have an incident edge in common with
node in this network. 
boolean 
allowsParallelEdges()
Returns true if this network allows parallel edges.

boolean 
allowsSelfLoops()
Returns true if this network allows selfloops (edges that connect a node to itself).

Graph<N> 
asGraph()
Returns a live view of this network as a
Graph . 
int 
degree(Object node)
Returns the count of
node 's incident edges , counting
selfloops twice (equivalently, the number of times an edge touches node ). 
ElementOrder<E> 
edgeOrder()
Returns the order of iteration for the elements of
edges() . 
Set<E> 
edges()
Returns all edges in this network, in the order specified by
edgeOrder() . 
Set<E> 
edgesConnecting(Object nodeU,
Object nodeV)
Returns the set of edges directly connecting
nodeU to nodeV . 
boolean 
equals(Object object)
For the default
Network implementations, returns true iff this == object
(reference equality). 
int 
hashCode()
For the default
Network implementations, returns System.identityHashCode(this) . 
Set<E> 
incidentEdges(Object node)
Returns the edges whose
incident nodes in this network include
node . 
EndpointPair<N> 
incidentNodes(Object edge)
Returns the nodes which are the endpoints of
edge in this network. 
int 
inDegree(Object node)
Returns the count of
node 's incoming edges in a directed
network. 
Set<E> 
inEdges(Object node)
Returns all edges in this network which can be traversed in the direction (if any) of the edge
to end at
node . 
boolean 
isDirected()
Returns true if the edges in this network are directed.

ElementOrder<N> 
nodeOrder()
Returns the order of iteration for the elements of
nodes() . 
Set<N> 
nodes()
Returns all nodes in this network, in the order specified by
nodeOrder() . 
int 
outDegree(Object node)
Returns the count of
node 's outgoing edges in a directed
network. 
Set<E> 
outEdges(Object node)
Returns all edges in this network which can be traversed in the direction (if any) of the edge
starting from
node . 
Set<N> 
predecessors(Object node)
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. 
Set<N> 
successors(Object node)
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. 
Set<N> nodes()
nodeOrder()
.Set<E> edges()
edgeOrder()
.Graph<N> asGraph()
Graph
. The resulting Graph
will have
an edge connecting node A to node B iff 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
.
boolean isDirected()
source node
to a target node
, while
undirected edges connect a pair of nodes to each other.boolean allowsParallelEdges()
UnsupportedOperationException
.boolean allowsSelfLoops()
UnsupportedOperationException
.ElementOrder<N> nodeOrder()
nodes()
.ElementOrder<E> edgeOrder()
edges()
.Set<N> adjacentNodes(Object node)
node
in this network.IllegalArgumentException
 if node
is not an element of this networkSet<N> predecessors(Object node)
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)
.
IllegalArgumentException
 if node
is not an element of this networkSet<N> successors(Object node)
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)
.
IllegalArgumentException
 if node
is not an element of this networkSet<E> incidentEdges(Object node)
incident nodes
in this network include
node
.IllegalArgumentException
 if node
is not an element of this networkSet<E> inEdges(Object node)
node
.
In a directed network, an incoming edge's EndpointPair.target()
equals node
.
In an undirected network, this is equivalent to incidentEdges(Object)
.
IllegalArgumentException
 if node
is not an element of this networkSet<E> outEdges(Object node)
node
.
In a directed network, an outgoing edge's EndpointPair.source()
equals node
.
In an undirected network, this is equivalent to incidentEdges(Object)
.
IllegalArgumentException
 if node
is not an element of this networkint degree(Object node)
node
's incident edges
, counting
selfloops 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
selfloops incident to node
).
If the count is greater than Integer.MAX_VALUE
, returns Integer.MAX_VALUE
.
IllegalArgumentException
 if node
is not an element of this networkint inDegree(Object node)
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
.
IllegalArgumentException
 if node
is not an element of this networkint outDegree(Object node)
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
.
IllegalArgumentException
 if node
is not an element of this networkEndpointPair<N> incidentNodes(Object edge)
edge
in this network.IllegalArgumentException
 if edge
is not an element of this networkSet<E> adjacentEdges(Object edge)
incident node
in common with
edge
. An edge is not considered adjacent to itself.IllegalArgumentException
 if edge
is not an element of this networkSet<E> edgesConnecting(Object nodeU, Object nodeV)
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.
IllegalArgumentException
 if nodeU
or nodeV
is not an element of this
networkboolean equals(@Nullable Object object)
Network
implementations, returns true iff this == object
(reference equality). External implementations are free to define this method as they see fit,
as long as they satisfy the Object.equals(Object)
contract.
To compare two Network
s based on their contents rather than their references, see
Graphs.equivalent(Network, Network)
.
int hashCode()
Network
implementations, returns System.identityHashCode(this)
.
External implementations are free to define this method as they see fit, as long as they
satisfy the Object.hashCode()
contract.Copyright © 20102016. All Rights Reserved.