public 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.
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.

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.

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.

EdgeFactory<V,E> 
getEdgeFactory()
Returns the edge factory using which this graph creates new edges.

V 
getEdgeSource(E e)
Returns the source vertex of an edge.

V 
getEdgeTarget(E e)
Returns the target vertex of an edge.

double 
getEdgeWeight(E e)
Returns the weight assigned to a given edge.

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.

java.util.Set<V> 
vertexSet()
Returns a set of the vertices contained in this graph.

java.util.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.EdgeFactory<V,E> getEdgeFactory()
E 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
EdgeFactory
. 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 returns
null
.
sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge.
null
.java.lang.IllegalArgumentException
 if source or target vertices are not
found in the graph.java.lang.NullPointerException
 if any of the specified vertices is
null
.getEdgeFactory()
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.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 is
null
.addEdge(Object, Object)
,
getEdgeFactory()
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.java.lang.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.java.util.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.
java.util.Set<E> edgesOf(V vertex)
vertex
 the vertex for which a set of touching edges is to be
returned.java.lang.IllegalArgumentException
 if vertex is not found in the graph.java.lang.NullPointerException
 if vertex is null
.boolean removeAllEdges(java.util.Collection<? extends E> edges)
removeEdge(Object)
method.edges
 edges to be removed from this graph.java.lang.NullPointerException
 if the specified edge collection is
null.removeEdge(Object)
,
containsEdge(Object)
java.util.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 no either vertex not
part of graphboolean removeAllVertices(java.util.Collection<? extends V> vertices)
removeVertex(Object)
method.vertices
 vertices to be removed from this graph.java.lang.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.java.util.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 interestdouble getEdgeWeight(E e)
WeightedGraph.DEFAULT_EDGE_WEIGHT
), allowing
weightedgraph algorithms to apply to them where meaningful.e
 edge of interestWeightedGraph