
 Type Parameters:
V
 the graph vertex typeE
 the graph edge type
 All Known Subinterfaces:
ListenableGraph<V,E>
 All Known Implementing Classes:
AbstractBaseGraph
,AbstractGraph
,AsGraphUnion
,AsSubgraph
,AsSynchronizedGraph
,AsUndirectedGraph
,AsUnmodifiableGraph
,AsUnweightedGraph
,AsWeightedGraph
,BaseGraphAdapter
,BaseNetworkAdapter
,BaseValueGraphAdapter
,BlockCutpointGraph
,DefaultDirectedGraph
,DefaultDirectedWeightedGraph
,DefaultListenableGraph
,DefaultUndirectedGraph
,DefaultUndirectedWeightedGraph
,DirectedAcyclicGraph
,DirectedMultigraph
,DirectedPseudograph
,DirectedWeightedMultigraph
,DirectedWeightedPseudograph
,EdgeReversedGraph
,FastutilMapGraph
,FastutilMapIntVertexGraph
,GraphDelegator
,ImmutableDoubleValueGraphAdapter
,ImmutableGraphAdapter
,ImmutableNetworkAdapter
,ImmutableValueGraphAdapter
,MaskSubgraph
,Multigraph
,MutableDoubleValueGraphAdapter
,MutableGraphAdapter
,MutableNetworkAdapter
,MutableValueGraphAdapter
,ParanoidGraph
,Pseudograph
,SimpleDirectedGraph
,SimpleDirectedWeightedGraph
,SimpleGraph
,SimpleWeightedGraph
,SparseIntDirectedGraph
,SparseIntDirectedWeightedGraph
,SparseIntUndirectedGraph
,SparseIntUndirectedWeightedGraph
,WeightedMultigraph
,WeightedPseudograph
public interface Graph<V,E>
The root interface in the graph hierarchy. A mathematical graphtheory graph objectG(V,E)
contains a setV
of vertices and a setE
of edges. Each edge e=(v1,v2) in E connects vertex v1 to vertex v2. for more information about graphs and their related definitions see http://mathworld.wolfram.com/Graph.html.This library generally follows the terminology found at: http://mathworld.wolfram.com/topics/GraphTheory.html. Implementation of this interface can provide simplegraphs, multigraphs, pseudographs etc. The package
org.jgrapht.graph
provides a gallery of abstract and concrete graph implementations.This library works best when vertices represent arbitrary objects and edges represent the relationships between them. Vertex and edge instances may be shared by more than one graph.
Through generics, a graph can be typed to specific classes for vertices
V
and edgesE<T>
. Such a graph can contain vertices of typeV
and all subtypes and Edges of typeE
and all subtypes.For guidelines on vertex and edge classes, see this wiki page.
 Author:
 Barak Naveh


Field Summary
Fields Modifier and Type Field Description static double
DEFAULT_EDGE_WEIGHT
The default weight for an edge.

Method Summary
All Methods Instance Methods Abstract Methods Default Methods Modifier and Type Method Description E
addEdge(V sourceVertex, V targetVertex)
Creates a new edge in this graph, going from the source vertex to the target vertex, and returns the created edge.boolean
addEdge(V sourceVertex, V targetVertex, E e)
Adds the specified edge to this graph, going from the source vertex to the target vertex.V
addVertex()
Creates a new vertex in this graph and returns it.boolean
addVertex(V v)
Adds the specified vertex to this graph if not already present.boolean
containsEdge(E e)
Returnstrue
if this graph contains the specified edge.boolean
containsEdge(V sourceVertex, V targetVertex)
Returnstrue
if and only if this graph contains an edge going from the source vertex to the target vertex.boolean
containsVertex(V v)
Returnstrue
if this graph contains the specified vertex.int
degreeOf(V vertex)
Returns the degree of the specified vertex.java.util.Set<E>
edgeSet()
Returns a set of the edges contained in this graph.java.util.Set<E>
edgesOf(V vertex)
Returns a set of all edges touching the specified vertex.java.util.Set<E>
getAllEdges(V sourceVertex, V targetVertex)
Returns a set of all edges connecting source vertex to target vertex if such vertices exist in this graph.E
getEdge(V sourceVertex, V targetVertex)
Returns an edge connecting source vertex to target vertex if such vertices and such edge exist in this graph.V
getEdgeSource(E e)
Returns the source vertex of an edge.java.util.function.Supplier<E>
getEdgeSupplier()
Return the edge supplier that the graph uses whenever it needs to create new edges.V
getEdgeTarget(E e)
Returns the target vertex of an edge.double
getEdgeWeight(E e)
Returns the weight assigned to a given edge.GraphType
getType()
Get the graph type.java.util.function.Supplier<V>
getVertexSupplier()
Return the vertex supplier that the graph uses whenever it needs to create new vertices.java.util.Set<E>
incomingEdgesOf(V vertex)
Returns a set of all edges incoming into the specified vertex.int
inDegreeOf(V vertex)
Returns the "in degree" of the specified vertex.int
outDegreeOf(V vertex)
Returns the "out degree" of the specified vertex.java.util.Set<E>
outgoingEdgesOf(V vertex)
Returns a set of all edges outgoing from the specified vertex.boolean
removeAllEdges(java.util.Collection<? extends E> edges)
Removes all the edges in this graph that are also contained in the specified edge collection.java.util.Set<E>
removeAllEdges(V sourceVertex, V targetVertex)
Removes all the edges going from the specified source vertex to the specified target vertex, and returns a set of all removed edges.boolean
removeAllVertices(java.util.Collection<? extends V> vertices)
Removes all the vertices in this graph that are also contained in the specified vertex collection.boolean
removeEdge(E e)
Removes the specified edge from the graph.E
removeEdge(V sourceVertex, V targetVertex)
Removes an edge going from source vertex to target vertex, if such vertices and such edge exist in this graph.boolean
removeVertex(V v)
Removes the specified vertex from this graph including all its touching edges if present.void
setEdgeWeight(E e, double weight)
Assigns a weight to an edge.default void
setEdgeWeight(V sourceVertex, V targetVertex, double weight)
Assigns a weight to an edge betweensourceVertex
andtargetVertex
.java.util.Set<V>
vertexSet()
Returns a set of the vertices contained in this graph.



Field Detail

DEFAULT_EDGE_WEIGHT
static final double DEFAULT_EDGE_WEIGHT
The default weight for an edge. See Also:
 Constant Field Values


Method Detail

getAllEdges
java.util.Set<E> getAllEdges(V sourceVertex, V targetVertex)
Returns a set of all edges connecting source vertex to target vertex if such vertices exist in this graph. If any of the vertices does not exist or isnull
, returnsnull
. If both vertices exist but no edges found, returns an empty set.In undirected graphs, some of the returned edges may have their source and target vertices in the opposite order. In simple graphs the returned set is either singleton set or empty set.
 Parameters:
sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge. Returns:
 a set of all edges connecting source vertex to target vertex.

getEdge
E getEdge(V sourceVertex, V targetVertex)
Returns an edge connecting source vertex to target vertex if such vertices and such edge exist in this graph. Otherwise returnsnull
. If any of the specified vertices isnull
returnsnull
In undirected graphs, the returned edge may have its source and target vertices in the opposite order.
 Parameters:
sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge. Returns:
 an edge connecting source vertex to target vertex.

getVertexSupplier
java.util.function.Supplier<V> getVertexSupplier()
Return the vertex supplier that the graph uses whenever it needs to create new vertices.A graph uses the vertex supplier to create new vertex objects whenever a user calls method
addVertex()
. Users can also create the vertex in user code and then use methodaddVertex(Object)
to add the vertex.In contrast with the
Supplier
interface, the vertex supplier has the additional requirement that a new and distinct result is returned every time it is invoked. More specifically for a new vertex to be added in a graphv
must not be equal to any other vertex in the graph. More formally, the graph must not contain any vertexv2
such thatv2.equals(v)
.Care must also be taken when interchanging calls to methods
addVertex(Object)
andaddVertex()
. In such a case the user must make sure never to add vertices in the graph using methodaddVertex(Object)
, which are going to be returned in the future by the supplied vertex supplier. Such a sequence will result into anIllegalArgumentException
when calling methodaddVertex()
. Returns:
 the vertex supplier or
null
if the graph has no such supplier

getEdgeSupplier
java.util.function.Supplier<E> getEdgeSupplier()
Return the edge supplier that the graph uses whenever it needs to create new edges.A graph uses the edge supplier to create new edge objects whenever a user calls method
addEdge(Object, Object)
. Users can also create the edge in user code and then use methodaddEdge(Object, Object, Object)
to add the edge.In contrast with the
Supplier
interface, the edge supplier has the additional requirement that a new and distinct result is returned every time it is invoked. More specifically for a new edge to be added in a graphe
must not be equal to any other edge in the graph (even if the graph allows edgemultiplicity). More formally, the graph must not contain any edgee2
such thate2.equals(e)
. Returns:
 the edge supplier
null
if the graph has no such supplier

addEdge
E addEdge(V sourceVertex, V targetVertex)
Creates a new edge in this graph, going from the source vertex to the target vertex, and returns the created edge. Some graphs do not allow edgemultiplicity. In such cases, if the graph already contains an edge from the specified source to the specified target, then this method does not change the graph and returnsnull
.The source and target vertices must already be contained in this graph. If they are not found in graph
IllegalArgumentException
is thrown.This method creates the new edge
e
using this graph's edge supplier (seegetEdgeSupplier()
). For the new edge to be addede
must not be equal to any other edge the graph (even if the graph allows edgemultiplicity). More formally, the graph must not contain any edgee2
such thate2.equals(e)
. If suche2
is found then the newly created edgee
is abandoned, the method leaves this graph unchanged and returnsnull
.If the underlying graph implementation's
getEdgeSupplier()
returnsnull
, then this method cannot create edges and throws anUnsupportedOperationException
. Parameters:
sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge. Returns:
 The newly created edge if added to the graph, otherwise
null
.  Throws:
java.lang.IllegalArgumentException
 if source or target vertices are not found in the graph.java.lang.NullPointerException
 if any of the specified vertices isnull
.java.lang.UnsupportedOperationException
 if the graph was not initialized with an edge supplier See Also:
getEdgeSupplier()

addEdge
boolean addEdge(V sourceVertex, V targetVertex, E e)
Adds the specified edge to this graph, going from the source vertex to the target vertex. More formally, adds the specified edge,e
, to this graph if this graph contains no edgee2
such thate2.equals(e)
. If this graph already contains such an edge, the call leaves this graph unchanged and returnsfalse
. Some graphs do not allow edgemultiplicity. In such cases, if the graph already contains an edge from the specified source to the specified target, then this method does not change the graph and returnsfalse
. If the edge was added to the graph, returnstrue
.The source and target vertices must already be contained in this graph. If they are not found in graph IllegalArgumentException is thrown.
 Parameters:
sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge.e
 edge to be added to this graph. Returns:
true
if this graph did not already contain the specified edge. Throws:
java.lang.IllegalArgumentException
 if source or target vertices are not found in the graph.java.lang.ClassCastException
 if the specified edge is not assignment compatible with the class of edges produced by the edge factory of this graph.java.lang.NullPointerException
 if any of the specified vertices isnull
. See Also:
addEdge(Object, Object)
,getEdgeSupplier()

addVertex
V addVertex()
Creates a new vertex in this graph and returns it.This method creates the new vertex
v
using this graph's vertex supplier (seegetVertexSupplier()
). For the new vertex to be addedv
must not be equal to any other vertex in the graph. More formally, the graph must not contain any vertexv2
such thatv2.equals(v)
. If suchv2
is found then the newly created vertexv
is abandoned, the method leaves this graph unchanged and throws anIllegalArgumentException
.If the underlying graph implementation's
getVertexSupplier()
returnsnull
, then this method cannot create vertices and throws anUnsupportedOperationException
.Care must also be taken when interchanging calls to methods
addVertex(Object)
andaddVertex()
. In such a case the user must make sure never to add vertices in the graph using methodaddVertex(Object)
, which are going to be returned in the future by the supplied vertex supplier. Such a sequence will result into anIllegalArgumentException
when calling methodaddVertex()
. Returns:
 The newly created vertex if added to the graph.
 Throws:
java.lang.IllegalArgumentException
 if the graph supplier returns a vertex which is already in the graphjava.lang.UnsupportedOperationException
 if the graph was not initialized with a vertex supplier See Also:
getVertexSupplier()

addVertex
boolean addVertex(V v)
Adds the specified vertex to this graph if not already present. More formally, adds the specified vertex,v
, to this graph if this graph contains no vertexu
such thatu.equals(v)
. If this graph already contains such vertex, the call leaves this graph unchanged and returnsfalse
. In combination with the restriction on constructors, this ensures that graphs never contain duplicate vertices. Parameters:
v
 vertex to be added to this graph. Returns:
true
if this graph did not already contain the specified vertex. Throws:
java.lang.NullPointerException
 if the specified vertex isnull
.

containsEdge
boolean containsEdge(V sourceVertex, V targetVertex)
Returnstrue
if and only if this graph contains an edge going from the source vertex to the target vertex. In undirected graphs the same result is obtained when source and target are inverted. If any of the specified vertices does not exist in the graph, or if isnull
, returnsfalse
. Parameters:
sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge. Returns:
true
if this graph contains the specified edge.

containsEdge
boolean containsEdge(E e)
Returnstrue
if this graph contains the specified edge. More formally, returnstrue
if and only if this graph contains an edgee2
such thate.equals(e2)
. If the specified edge isnull
returnsfalse
. Parameters:
e
 edge whose presence in this graph is to be tested. Returns:
true
if this graph contains the specified edge.

containsVertex
boolean containsVertex(V v)
Returnstrue
if this graph contains the specified vertex. More formally, returnstrue
if and only if this graph contains a vertexu
such thatu.equals(v)
. If the specified vertex isnull
returnsfalse
. Parameters:
v
 vertex whose presence in this graph is to be tested. Returns:
true
if this graph contains the specified vertex.

edgeSet
java.util.Set<E> edgeSet()
Returns a set of the edges contained in this graph. The set is backed by the graph, so changes to the graph are reflected in the set. If the graph is modified while an iteration over the set is in progress, the results of the iteration are undefined.The graph implementation may maintain a particular set ordering (e.g. via
LinkedHashSet
) for deterministic iteration, but this is not required. It is the responsibility of callers who rely on this behavior to only use graph implementations which support it. Returns:
 a set of the edges contained in this graph.

degreeOf
int degreeOf(V vertex)
Returns the degree of the specified vertex.A degree of a vertex in an undirected graph is the number of edges touching that vertex. Edges with same source and target vertices (selfloops) are counted twice.
In directed graphs this method returns the sum of the "in degree" and the "out degree".
 Parameters:
vertex
 vertex whose degree is to be calculated. Returns:
 the degree of the specified vertex.
 Throws:
java.lang.IllegalArgumentException
 if vertex is not found in the graph.java.lang.NullPointerException
 if vertex isnull
.

edgesOf
java.util.Set<E> edgesOf(V vertex)
Returns a set of all edges touching the specified vertex. If no edges are touching the specified vertex returns an empty set. Parameters:
vertex
 the vertex for which a set of touching edges is to be returned. Returns:
 a set of all edges touching the specified vertex.
 Throws:
java.lang.IllegalArgumentException
 if vertex is not found in the graph.java.lang.NullPointerException
 if vertex isnull
.

inDegreeOf
int inDegreeOf(V vertex)
Returns the "in degree" of the specified vertex.The "in degree" of a vertex in a directed graph is the number of inward directed edges from that vertex. See http://mathworld.wolfram.com/Indegree.html.
In the case of undirected graphs this method returns the number of edges touching the vertex. Edges with same source and target vertices (selfloops) are counted twice.
 Parameters:
vertex
 vertex whose degree is to be calculated. Returns:
 the degree of the specified vertex.
 Throws:
java.lang.IllegalArgumentException
 if vertex is not found in the graph.java.lang.NullPointerException
 if vertex isnull
.

incomingEdgesOf
java.util.Set<E> incomingEdgesOf(V vertex)
Returns a set of all edges incoming into the specified vertex.In the case of undirected graphs this method returns all edges touching the vertex, thus, some of the returned edges may have their source and target vertices in the opposite order.
 Parameters:
vertex
 the vertex for which the list of incoming edges to be returned. Returns:
 a set of all edges incoming into the specified vertex.
 Throws:
java.lang.IllegalArgumentException
 if vertex is not found in the graph.java.lang.NullPointerException
 if vertex isnull
.

outDegreeOf
int outDegreeOf(V vertex)
Returns the "out degree" of the specified vertex.The "out degree" of a vertex in a directed graph is the number of outward directed edges from that vertex. See http://mathworld.wolfram.com/Outdegree.html.
In the case of undirected graphs this method returns the number of edges touching the vertex. Edges with same source and target vertices (selfloops) are counted twice.
 Parameters:
vertex
 vertex whose degree is to be calculated. Returns:
 the degree of the specified vertex.
 Throws:
java.lang.IllegalArgumentException
 if vertex is not found in the graph.java.lang.NullPointerException
 if vertex isnull
.

outgoingEdgesOf
java.util.Set<E> outgoingEdgesOf(V vertex)
Returns a set of all edges outgoing from the specified vertex.In the case of undirected graphs this method returns all edges touching the vertex, thus, some of the returned edges may have their source and target vertices in the opposite order.
 Parameters:
vertex
 the vertex for which the list of outgoing edges to be returned. Returns:
 a set of all edges outgoing from the specified vertex.
 Throws:
java.lang.IllegalArgumentException
 if vertex is not found in the graph.java.lang.NullPointerException
 if vertex isnull
.

removeAllEdges
boolean removeAllEdges(java.util.Collection<? extends E> edges)
Removes all the edges in this graph that are also contained in the specified edge collection. After this call returns, this graph will contain no edges in common with the specified edges. This method will invoke theremoveEdge(Object)
method. Parameters:
edges
 edges to be removed from this graph. Returns:
true
if this graph changed as a result of the call Throws:
java.lang.NullPointerException
 if the specified edge collection isnull
. See Also:
removeEdge(Object)
,containsEdge(Object)

removeAllEdges
java.util.Set<E> removeAllEdges(V sourceVertex, V targetVertex)
Removes all the edges going from the specified source vertex to the specified target vertex, and returns a set of all removed edges. Returnsnull
if any of the specified vertices does not exist in the graph. If both vertices exist but no edge is found, returns an empty set. This method will either invoke theremoveEdge(Object)
method, or theremoveEdge(Object, Object)
method. Parameters:
sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge. Returns:
 the removed edges, or
null
if either vertex is not part of graph

removeAllVertices
boolean removeAllVertices(java.util.Collection<? extends V> vertices)
Removes all the vertices in this graph that are also contained in the specified vertex collection. After this call returns, this graph will contain no vertices in common with the specified vertices. This method will invoke theremoveVertex(Object)
method. Parameters:
vertices
 vertices to be removed from this graph. Returns:
true
if this graph changed as a result of the call Throws:
java.lang.NullPointerException
 if the specified vertex collection isnull
. See Also:
removeVertex(Object)
,containsVertex(Object)

removeEdge
E removeEdge(V sourceVertex, V targetVertex)
Removes an edge going from source vertex to target vertex, if such vertices and such edge exist in this graph. Returns the edge if removed ornull
otherwise. Parameters:
sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge. Returns:
 The removed edge, or
null
if no edge removed.

removeEdge
boolean removeEdge(E e)
Removes the specified edge from the graph. Removes the specified edge from this graph if it is present. More formally, removes an edgee2
such thate2.equals(e)
, if the graph contains such edge. Returnstrue
if the graph contained the specified edge. (The graph will not contain the specified edge once the call returns).If the specified edge is
null
returnsfalse
. Parameters:
e
 edge to be removed from this graph, if present. Returns:
true
if and only if the graph contained the specified edge.

removeVertex
boolean removeVertex(V v)
Removes the specified vertex from this graph including all its touching edges if present. More formally, if the graph contains a vertexu
such thatu.equals(v)
, the call removes all edges that touchu
and then removesu
itself. If no suchu
is found, the call leaves the graph unchanged. Returnstrue
if the graph contained the specified vertex. (The graph will not contain the specified vertex once the call returns).If the specified vertex is
null
returnsfalse
. Parameters:
v
 vertex to be removed from this graph, if present. Returns:
true
if the graph contained the specified vertex;false
otherwise.

vertexSet
java.util.Set<V> vertexSet()
Returns a set of the vertices contained in this graph. The set is backed by the graph, so changes to the graph are reflected in the set. If the graph is modified while an iteration over the set is in progress, the results of the iteration are undefined.The graph implementation may maintain a particular set ordering (e.g. via
LinkedHashSet
) for deterministic iteration, but this is not required. It is the responsibility of callers who rely on this behavior to only use graph implementations which support it. Returns:
 a set view of the vertices contained in this graph.

getEdgeSource
V getEdgeSource(E e)
Returns the source vertex of an edge. For an undirected graph, source and target are distinguishable designations (but without any mathematical meaning). Parameters:
e
 edge of interest Returns:
 source vertex

getEdgeTarget
V getEdgeTarget(E e)
Returns the target vertex of an edge. For an undirected graph, source and target are distinguishable designations (but without any mathematical meaning). Parameters:
e
 edge of interest Returns:
 target vertex

getType
GraphType getType()
Get the graph type. The graph type can be used to query for additional metadata such as whether the graph supports directed or undirected edges, selfloops, multiple (parallel) edges, weights, etc. Returns:
 the graph type

getEdgeWeight
double getEdgeWeight(E e)
Returns the weight assigned to a given edge. Unweighted graphs return 1.0 (as defined byDEFAULT_EDGE_WEIGHT
), allowing weightedgraph algorithms to apply to them when meaningful. Parameters:
e
 edge of interest Returns:
 edge weight

setEdgeWeight
void setEdgeWeight(E e, double weight)
Assigns a weight to an edge. Parameters:
e
 edge on which to set weightweight
 new weight for edge Throws:
java.lang.UnsupportedOperationException
 if the graph does not support weights

setEdgeWeight
default void setEdgeWeight(V sourceVertex, V targetVertex, double weight)
Assigns a weight to an edge betweensourceVertex
andtargetVertex
. If no edge exists betweensourceVertex
andtargetVertex
or either of these vertices isnull
, aNullPointerException
is thrown.When there exist multiple edges between
sourceVertex
andtargetVertex
, consider usingsetEdgeWeight(Object, double)
instead. Parameters:
sourceVertex
 source vertex of the edgetargetVertex
 target vertex of the edgeweight
 new weight for edge Throws:
java.lang.UnsupportedOperationException
 if the graph does not support weights

