V
 the graph vertex typeE
 the graph edge typepublic interface Graph<V,E>
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 edges
E<T>
. Such a graph can contain vertices of type V
and all
subtypes and Edges of type
E
and all subtypes.
For guidelines on vertex and edge classes, see this wiki page.
Modifier and Type  Field and Description 

static double 
DEFAULT_EDGE_WEIGHT
The default weight for an edge.

Modifier and Type  Method and 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)
Returns true if this graph contains the specified edge.

boolean 
containsEdge(V sourceVertex,
V targetVertex)
Returns true if and only if this graph contains an edge going from the source vertex
to the target vertex.

boolean 
containsVertex(V v)
Returns true if this graph contains the specified vertex.

int 
degreeOf(V vertex)
Returns the degree of the specified vertex.

Set<E> 
edgeSet()
Returns a set of the edges contained in this graph.

Set<E> 
edgesOf(V vertex)
Returns a set of all edges touching the specified vertex.

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.

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.

Supplier<V> 
getVertexSupplier()
Return the vertex supplier that the graph uses whenever it needs to create new vertices.

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.

Set<E> 
outgoingEdgesOf(V vertex)
Returns a set of all edges outgoing from the specified vertex.

boolean 
removeAllEdges(Collection<? extends E> edges)
Removes all the edges in this graph that are also contained in the specified edge collection.

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(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 between
sourceVertex and targetVertex . 
Set<V> 
vertexSet()
Returns a set of the vertices contained in this graph.

static final double DEFAULT_EDGE_WEIGHT
Set<E> getAllEdges(V sourceVertex, V targetVertex)
null
, returns
null
. 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.
sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge.E getEdge(V sourceVertex, V targetVertex)
null
. If any of the specified vertices is null
returns null
In undirected graphs, the returned edge may have its source and target vertices in the opposite order.
sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge.Supplier<V> getVertexSupplier()
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 method
addVertex(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 graph v
must not be equal
to any other vertex in the graph. More formally, the graph must not contain any vertex
v2
such that v2.equals(v)
.
Care must also be taken when interchanging calls to methods addVertex(Object)
and addVertex()
. In such a case the user must make sure never to add vertices
in the graph using method addVertex(Object)
, which are going to be returned in
the future by the supplied vertex supplier. Such a sequence will result into an
IllegalArgumentException
when calling method addVertex()
.
null
if the graph has no such supplierSupplier<E> getEdgeSupplier()
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 method addEdge(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 graph e
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 edge e2
such that e2.equals(e)
.
null
if the graph has no such supplierE addEdge(V sourceVertex, V targetVertex)
null
.
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 (see
getEdgeSupplier()
). For the new edge to be added e
must not be
equal to any other edge the graph (even if the graph allows edgemultiplicity). More
formally, the graph must not contain any edge e2
such that
e2.equals(e)
. If such
e2
is found then the newly created edge e
is abandoned, the method leaves
this graph unchanged and returns null
.
If the underlying graph implementation's getEdgeSupplier()
returns
null
, then this method cannot create edges and throws an
UnsupportedOperationException
.
sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge.
null
.IllegalArgumentException
 if source or target vertices are not found in the graph.NullPointerException
 if any of the specified vertices is null
.UnsupportedOperationException
 if the graph was not initialized with an edge suppliergetEdgeSupplier()
boolean addEdge(V sourceVertex, V targetVertex, E e)
e
, to this graph if this graph contains no edge e2
such that
e2.equals(e)
. If this graph already contains such an edge, the call leaves this
graph unchanged and returns false. Some graphs do not allow edgemultiplicity. In
such cases, if the graph already contains an edge from the specified source to the specified
target, than this method does not change the graph and returns
false
. If the edge was added to the graph, returns
true
.
The source and target vertices must already be contained in this graph. If they are not found in graph IllegalArgumentException is thrown.
sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge.e
 edge to be added to this graph.IllegalArgumentException
 if source or target vertices are not found in the graph.ClassCastException
 if the specified edge is not assignment compatible with the class
of edges produced by the edge factory of this graph.NullPointerException
 if any of the specified vertices is
null
.addEdge(Object, Object)
,
getEdgeSupplier()
V addVertex()
This method creates the new vertex v
using this graph's vertex supplier (see
getVertexSupplier()
). For the new vertex to be added v
must not
be equal to any other vertex in the graph. More formally, the graph must not contain any
vertex v2
such that v2.equals(v)
. If such
v2
is found then the newly created vertex v
is abandoned, the method
leaves this graph unchanged and throws an IllegalArgumentException
.
If the underlying graph implementation's getVertexSupplier()
returns
null
, then this method cannot create vertices and throws an
UnsupportedOperationException
.
Care must also be taken when interchanging calls to methods addVertex(Object)
and addVertex()
. In such a case the user must make sure never to add vertices
in the graph using method addVertex(Object)
, which are going to be returned in
the future by the supplied vertex supplier. Such a sequence will result into an
IllegalArgumentException
when calling method addVertex()
.
IllegalArgumentException
 if the graph supplier returns a vertex which is already in
the graphUnsupportedOperationException
 if the graph was not initialized with a vertex suppliergetVertexSupplier()
boolean addVertex(V v)
v
, to this graph if this graph contains no vertex
u
such that
u.equals(v)
. If this graph already contains such vertex, the call leaves this graph
unchanged and returns false. In combination with the restriction on constructors,
this ensures that graphs never contain duplicate vertices.v
 vertex to be added to this graph.NullPointerException
 if the specified vertex is
null
.boolean containsEdge(V sourceVertex, V targetVertex)
null
, returns false
.sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge.boolean containsEdge(E e)
e2
such that
e.equals(e2)
. If the specified edge is null
returns
false
.e
 edge whose presence in this graph is to be tested.boolean containsVertex(V v)
u
such that
u.equals(v)
. If the specified vertex is null
returns
false
.v
 vertex whose presence in this graph is to be tested.Set<E> edgeSet()
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.
int degreeOf(V 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".
vertex
 vertex whose degree is to be calculated.IllegalArgumentException
 if vertex is not found in the graph.NullPointerException
 if vertex is null
.Set<E> edgesOf(V vertex)
vertex
 the vertex for which a set of touching edges is to be returned.IllegalArgumentException
 if vertex is not found in the graph.NullPointerException
 if vertex is null
.int inDegreeOf(V 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.
vertex
 vertex whose degree is to be calculated.IllegalArgumentException
 if vertex is not found in the graph.NullPointerException
 if vertex is null
.Set<E> incomingEdgesOf(V 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.
vertex
 the vertex for which the list of incoming edges to be returned.IllegalArgumentException
 if vertex is not found in the graph.NullPointerException
 if vertex is null
.int outDegreeOf(V 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.
vertex
 vertex whose degree is to be calculated.IllegalArgumentException
 if vertex is not found in the graph.NullPointerException
 if vertex is null
.Set<E> outgoingEdgesOf(V 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.
vertex
 the vertex for which the list of outgoing edges to be returned.IllegalArgumentException
 if vertex is not found in the graph.NullPointerException
 if vertex is null
.boolean removeAllEdges(Collection<? extends E> edges)
removeEdge(Object)
method.edges
 edges to be removed from this graph.NullPointerException
 if the specified edge collection is
null.removeEdge(Object)
,
containsEdge(Object)
Set<E> removeAllEdges(V sourceVertex, V targetVertex)
null
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 the removeEdge(Object)
method, or the
removeEdge(Object, Object)
method.sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge.null
if either vertex is not part of graphboolean removeAllVertices(Collection<? extends V> vertices)
removeVertex(Object)
method.vertices
 vertices to be removed from this graph.NullPointerException
 if the specified vertex collection is
null.removeVertex(Object)
,
containsVertex(Object)
E removeEdge(V sourceVertex, V targetVertex)
null
otherwise.sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge.null
if no edge removed.boolean removeEdge(E e)
e2
such that e2.equals(e)
, if the graph contains such edge. Returns
true 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
returns
false
.
e
 edge to be removed from this graph, if present.true
if and only if the graph contained the specified edge.boolean removeVertex(V v)
u
such that u.equals(v)
, the call removes all edges that touch
u
and then removes u
itself. If no such u
is found,
the call leaves the graph unchanged. Returns true 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
returns
false
.
v
 vertex to be removed from this graph, if present.true
if the graph contained the specified vertex; false
otherwise.Set<V> vertexSet()
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.
V getEdgeSource(E e)
e
 edge of interestV getEdgeTarget(E e)
e
 edge of interestGraphType getType()
double getEdgeWeight(E e)
DEFAULT_EDGE_WEIGHT
), allowing weightedgraph algorithms to apply to them when
meaningful.e
 edge of interestvoid setEdgeWeight(E e, double weight)
e
 edge on which to set weightweight
 new weight for edgeUnsupportedOperationException
 if the graph does not support weightsdefault void setEdgeWeight(V sourceVertex, V targetVertex, double weight)
sourceVertex
and targetVertex
.
If no edge exists between sourceVertex
and targetVertex
or either
of these vertices is null
, a NullPointerException
is thrown.
When there exist multiple edges between sourceVertex
and
targetVertex
, consider using setEdgeWeight(Object, double)
instead.
sourceVertex
 source vertex of the edgetargetVertex
 target vertex of the edgeweight
 new weight for edgeUnsupportedOperationException
 if the graph does not support weightsCopyright © 2019. All rights reserved.