 Type Parameters:
V
 the graph vertex typeE
 the graph edge type
 All Implemented Interfaces:
java.io.Serializable
,Graph<V,E>
public class AsSynchronizedGraph<V,E> extends GraphDelegator<V,E> implements Graph<V,E>, java.io.Serializable
Users need to manually synchronize on edge supplier (see Graph.getEdgeSupplier()
) if
creating an edge needs to access shared resources. Failure to follow this advice may result in
nondeterministic behavior.
For all methods returning a Set, the Graph guarantees that all operations on the returned Set do
not affect the backing Graph. For edgeSet
and vertexSet
methods, the
returned Set is backed by the underlying graph, but when a traversal over the set is started via
a method such as iterator(), a snapshot of the underlying Set is copied for iteration purposes.
For edgesOf
, incomingEdgesOf
and outgoingEdgesOf
methods,
the returned Set is a unmodifiable copy of the result produced by the underlying Graph. Users can
control whether those copies should be cached; caching may significantly increase memory
requirements. If users decide to cache those copies and the backing graph's changes don't affect
them, those copies will be returned the next time the method is called. If the backing graph's
changes affect them, they will be removed from cache and recreated the next time the method is
called. If users decide to not cache those copies, the graph will create ephemeral copies every
time the method is called. For other methods returning a Set, the Set is just the backing Graph's
return.
As an alternative, a copyless mode is supported. When enabled, no collection copies are
made at all (and hence the cache setting is ignored). This requires the caller to explicitly
synchronize iteration via the getLock()
method. This approach requires quite a bit of care
on the part of the calling application, so it is disabled by default.
Even though this graph implementation is threadsafe, callers should still be aware of potential
hazards from removal methods. If calling code obtains a reference to a vertex or edge from the
graph, and then calls another graph method to access information about that object, an
IllegalArgumentException
may be thrown if another thread has concurrently removed that
object. Therefore, calling the remove methods concurrently with a typical algorithm is likely to
cause the algorithm to fail with an IllegalArgumentException
. So really the main
concurrent read/write use case is addonly.
eg: If threadA tries to get all edges touching a certain vertex after threadB removes the vertex,
the algorithm will be interrupted by IllegalArgumentException
.
Thread threadA = new Thread(() > {
Set vertices = graph.vertexSet();
for (Object v : vertices) {
// IllegalArgumentException
may be thrown since other threads may have removed
// the vertex.
Set edges = graph.edgesOf(v);
doOtherThings();
}
});
Thread threadB = new Thread(() > {
Set vertices = graph.vertexSet();
for (Object v : vertices) {
if (someConditions) {
graph.removeVertex(v);
}
}
});
One way to avoid the hazard noted above is for the calling application to explicitly synchronize
all iterations using the getLock()
method.
The created Graph's hashCode is equal to the backing set's hashCode. And the created Graph is equal to another Graph if they are the same Graph or the backing Graph is equal to the other Graph.
 Author:
 CHEN Kui
 See Also:
 Serialized Form

Nested Class Summary
Nested Classes Modifier and Type Class Description static class
AsSynchronizedGraph.Builder<V,E>
A builder forAsSynchronizedGraph
. 
Field Summary

Constructor Summary
Constructors Constructor Description AsSynchronizedGraph(Graph<V,E> g)
Constructor for AsSynchronizedGraph with default settings (cache disabled, nonfair mode, and copyless mode disabled). 
Method Summary
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.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.boolean
equals(java.lang.Object o)
Indicates whether some other object is "equal to" this graph.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.V
getEdgeTarget(E e)
Returns the target vertex of an edge.double
getEdgeWeight(E e)
Returns the weight assigned to a given edge.java.util.concurrent.locks.ReentrantReadWriteLock
getLock()
Get the read/write lock used to synchronize all access to this graph.int
hashCode()
Returns a hash code value for this graph.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.boolean
isCacheEnabled()
Return whether the graph uses cache foredgesOf
,incomingEdgesOf
andoutgoingEdgesOf
methods.boolean
isCopyless()
Return whether copyless mode is used for collectionreturning methods.boolean
isFair()
Return whether fair mode is used for synchronizing access to this graph.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.AsSynchronizedGraph<V,E>
setCache(boolean cacheEnabled)
Set the cache strategy foredgesOf
,incomingEdgesOf
andoutgoingEdgesOf
methods.void
setEdgeWeight(E e, double weight)
Assigns a weight to an edge.java.lang.String
toString()
Returns a string of the parenthesized pair (V, E) representing this G=(V,E) graph.java.util.Set<V>
vertexSet()
Returns a set of the vertices contained in this graph.Methods inherited from class org.jgrapht.graph.GraphDelegator
addVertex, getDelegate, getEdgeSupplier, getType, getVertexSupplier
Methods inherited from class org.jgrapht.graph.AbstractGraph
assertVertexExist, removeAllEdges, toStringFromSets
Methods inherited from class java.lang.Object
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
Methods inherited from interface org.jgrapht.Graph
addVertex, getEdgeSupplier, getType, getVertexSupplier, iterables, setEdgeWeight

Constructor Details

AsSynchronizedGraph
Constructor for AsSynchronizedGraph with default settings (cache disabled, nonfair mode, and copyless mode disabled). Parameters:
g
 the backing graph (the delegate)


Method Details

getAllEdges
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.
 Specified by:
getAllEdges
in interfaceGraph<V,E>
 Overrides:
getAllEdges
in classGraphDelegator<V,E>
 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
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.

addEdge
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 (seeGraph.getEdgeSupplier()
). 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
Graph.getEdgeSupplier()
returnsnull
, then this method cannot create edges and throws anUnsupportedOperationException
. Specified by:
addEdge
in interfaceGraph<V,E>
 Overrides:
addEdge
in classGraphDelegator<V,E>
 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
.  See Also:
Graph.getEdgeSupplier()

addEdge
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.
 Specified by:
addEdge
in interfaceGraph<V,E>
 Overrides:
addEdge
in classGraphDelegator<V,E>
 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. See Also:
Graph.addEdge(Object, Object)
,Graph.getEdgeSupplier()

addVertex
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. 
containsEdge
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
. Specified by:
containsEdge
in interfaceGraph<V,E>
 Overrides:
containsEdge
in classAbstractGraph<V,E>
 Parameters:
sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge. Returns:
true
if this graph contains the specified edge. See Also:
Graph.containsEdge(Object, Object)

containsEdge
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
. Specified by:
containsEdge
in interfaceGraph<V,E>
 Overrides:
containsEdge
in classGraphDelegator<V,E>
 Parameters:
e
 edge whose presence in this graph is to be tested. Returns:
true
if this graph contains the specified edge.

containsVertex
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
. Specified by:
containsVertex
in interfaceGraph<V,E>
 Overrides:
containsVertex
in classGraphDelegator<V,E>
 Parameters:
v
 vertex whose presence in this graph is to be tested. Returns:
true
if this graph contains the specified vertex.

degreeOf
Returns the degree of the specified vertex. 
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. 
edgesOf
Returns a set of all edges touching the specified vertex. If no edges are touching the specified vertex returns an empty set. 
inDegreeOf
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.
 Specified by:
inDegreeOf
in interfaceGraph<V,E>
 Overrides:
inDegreeOf
in classGraphDelegator<V,E>
 Parameters:
vertex
 vertex whose degree is to be calculated. Returns:
 the degree of the specified vertex.

incomingEdgesOf
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.
 Specified by:
incomingEdgesOf
in interfaceGraph<V,E>
 Overrides:
incomingEdgesOf
in classGraphDelegator<V,E>
 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.

outDegreeOf
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.
 Specified by:
outDegreeOf
in interfaceGraph<V,E>
 Overrides:
outDegreeOf
in classGraphDelegator<V,E>
 Parameters:
vertex
 vertex whose degree is to be calculated. Returns:
 the degree of the specified vertex.

outgoingEdgesOf
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.
 Specified by:
outgoingEdgesOf
in interfaceGraph<V,E>
 Overrides:
outgoingEdgesOf
in classGraphDelegator<V,E>
 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.

removeAllEdges
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 theGraph.removeEdge(Object)
method. Specified by:
removeAllEdges
in interfaceGraph<V,E>
 Overrides:
removeAllEdges
in classAbstractGraph<V,E>
 Parameters:
edges
 edges to be removed from this graph. Returns:
true
if this graph changed as a result of the call See Also:
Graph.removeAllEdges(Collection)

removeAllEdges
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 theGraph.removeEdge(Object)
method, or theGraph.removeEdge(Object, Object)
method. Specified by:
removeAllEdges
in interfaceGraph<V,E>
 Overrides:
removeAllEdges
in classAbstractGraph<V,E>
 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  See Also:
Graph.removeAllEdges(Object, Object)

removeAllVertices
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 theGraph.removeVertex(Object)
method. Specified by:
removeAllVertices
in interfaceGraph<V,E>
 Overrides:
removeAllVertices
in classAbstractGraph<V,E>
 Parameters:
vertices
 vertices to be removed from this graph. Returns:
true
if this graph changed as a result of the call See Also:
Graph.removeAllVertices(Collection)

removeEdge
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
. Specified by:
removeEdge
in interfaceGraph<V,E>
 Overrides:
removeEdge
in classGraphDelegator<V,E>
 Parameters:
e
 edge to be removed from this graph, if present. Returns:
true
if and only if the graph contained the specified edge.

removeEdge
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. Specified by:
removeEdge
in interfaceGraph<V,E>
 Overrides:
removeEdge
in classGraphDelegator<V,E>
 Parameters:
sourceVertex
 source vertex of the edge.targetVertex
 target vertex of the edge. Returns:
 The removed edge, or
null
if no edge removed.

removeVertex
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
. Specified by:
removeVertex
in interfaceGraph<V,E>
 Overrides:
removeVertex
in classGraphDelegator<V,E>
 Parameters:
v
 vertex to be removed from this graph, if present. Returns:
true
if the graph contained the specified vertex;false
otherwise.

toString
public java.lang.String toString()Returns a string of the parenthesized pair (V, E) representing this G=(V,E) graph. 'V' is the string representation of the vertex set, and 'E' is the string representation of the edge set. Overrides:
toString
in classGraphDelegator<V,E>
 Returns:
 a string representation of this graph.

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. 
getEdgeSource
Returns the source vertex of an edge. For an undirected graph, source and target are distinguishable designations (but without any mathematical meaning). Specified by:
getEdgeSource
in interfaceGraph<V,E>
 Overrides:
getEdgeSource
in classGraphDelegator<V,E>
 Parameters:
e
 edge of interest Returns:
 source vertex

getEdgeTarget
Returns the target vertex of an edge. For an undirected graph, source and target are distinguishable designations (but without any mathematical meaning). Specified by:
getEdgeTarget
in interfaceGraph<V,E>
 Overrides:
getEdgeTarget
in classGraphDelegator<V,E>
 Parameters:
e
 edge of interest Returns:
 target vertex

getEdgeWeight
Returns the weight assigned to a given edge. Unweighted graphs return 1.0 (as defined byGraph.DEFAULT_EDGE_WEIGHT
), allowing weightedgraph algorithms to apply to them when meaningful. Specified by:
getEdgeWeight
in interfaceGraph<V,E>
 Overrides:
getEdgeWeight
in classGraphDelegator<V,E>
 Parameters:
e
 edge of interest Returns:
 edge weight

setEdgeWeight
Assigns a weight to an edge. Specified by:
setEdgeWeight
in interfaceGraph<V,E>
 Overrides:
setEdgeWeight
in classGraphDelegator<V,E>
 Parameters:
e
 edge on which to set weightweight
 new weight for edge

isCacheEnabled
public boolean isCacheEnabled()Return whether the graph uses cache foredgesOf
,incomingEdgesOf
andoutgoingEdgesOf
methods. Returns:
true
if cache is in use,false
if cache is not in use.

isCopyless
public boolean isCopyless()Return whether copyless mode is used for collectionreturning methods. Returns:
true
if the graph uses copyless mode,false
otherwise

setCache
Set the cache strategy foredgesOf
,incomingEdgesOf
andoutgoingEdgesOf
methods. Parameters:
cacheEnabled
 a flag whether to use cache for those methods, iftrue
, cache will be used for those methods, otherwise cache will not be used. Returns:
 the AsSynchronizedGraph

hashCode
public int hashCode()Returns a hash code value for this graph. The hash code of a graph is defined to be the sum of the hash codes of vertices and edges in the graph. It is also based on graph topology and edges weights. Overrides:
hashCode
in classAbstractGraph<V,E>
 Returns:
 the hash code value this graph
 See Also:
Object.hashCode()

equals
public boolean equals(java.lang.Object o)Indicates whether some other object is "equal to" this graph. Returnstrue
if the given object is also a graph, the two graphs are instances of the same graph class, have identical vertices and edges sets with the same weights. Overrides:
equals
in classAbstractGraph<V,E>
 Parameters:
o
 object to be compared for equality with this graph Returns:
true
if the specified object is equal to this graph See Also:
Object.equals(Object)

isFair
public boolean isFair()Return whether fair mode is used for synchronizing access to this graph. Returns:
true
if the graph uses fair mode,false
if nonfair mode

getLock
public java.util.concurrent.locks.ReentrantReadWriteLock getLock()Get the read/write lock used to synchronize all access to this graph. This can be used by calling applications to explicitly synchronize compound sequences of graph accessses. The lock is reentrant, so the locks acquired internally by AsSynchronizedGraph will not interfere with the caller's acquired lock. However, write methods MUST NOT be called while holding a read lock, otherwise a deadlock will occur. Returns:
 the reentrant read/write lock used to synchronize all access to this graph
