N
 Node parameter type@Beta public abstract class AbstractGraph<N> extends Object implements Graph<N>
Graph
. It is recommended to extend this
class rather than implement Graph
directly.Constructor and Description 

AbstractGraph() 
Modifier and Type  Method and Description 

int 
degree(N node)
Returns the count of
node 's incident edges, counting selfloops twice (equivalently,
the number of times an edge touches node ). 
protected long 
edgeCount()
Returns the number of edges in this graph; used to calculate the size of
edges() . 
Set<EndpointPair<N>> 
edges()

boolean 
equals(@Nullable Object obj)
Indicates whether some other object is "equal to" this one.

boolean 
hasEdgeConnecting(EndpointPair<N> endpoints)
Returns true if there is an edge that directly connects
endpoints (in the order, if
any, specified by endpoints ). 
boolean 
hasEdgeConnecting(N nodeU,
N nodeV)
Returns true if there is an edge that directly connects
nodeU to nodeV . 
int 
hashCode()
Returns a hash code value for the object.

Set<EndpointPair<N>> 
incidentEdges(N node)
Returns the edges in this graph whose endpoints include
node . 
int 
inDegree(N node)
Returns the count of
node 's incoming edges (equal to predecessors(node).size() )
in a directed graph. 
protected boolean 
isOrderingCompatible(EndpointPair<?> endpoints) 
int 
outDegree(N node)
Returns the count of
node 's outgoing edges (equal to successors(node).size() )
in a directed graph. 
String 
toString()
Returns a string representation of this graph.

protected void 
validateEndpoints(EndpointPair<?> endpoints)
Throws
IllegalArgumentException if the ordering of endpoints is not compatible
with the directionality of this graph. 
clone, finalize, getClass, notify, notifyAll, wait, wait, wait
adjacentNodes, allowsSelfLoops, degree, edges, hasEdgeConnecting, hasEdgeConnecting, incidentEdges, inDegree, isDirected, nodeOrder, nodes, outDegree, predecessors, successors
public AbstractGraph()
public final boolean equals(@Nullable Object obj)
java.lang.Object
The equals
method implements an equivalence relation
on nonnull object references:
x
, x.equals(x)
should return
true
.
x
and y
, x.equals(y)
should return true
if and only if
y.equals(x)
returns true
.
x
, y
, and z
, if
x.equals(y)
returns true
and
y.equals(z)
returns true
, then
x.equals(z)
should return true
.
x
and y
, multiple invocations of
x.equals(y)
consistently return true
or consistently return false
, provided no
information used in equals
comparisons on the
objects is modified.
x
,
x.equals(null)
should return false
.
The equals
method for class Object
implements
the most discriminating possible equivalence relation on objects;
that is, for any nonnull reference values x
and
y
, this method returns true
if and only
if x
and y
refer to the same object
(x == y
has the value true
).
Note that it is generally necessary to override the hashCode
method whenever this method is overridden, so as to maintain the
general contract for the hashCode
method, which states
that equal objects must have equal hash codes.
public final int hashCode()
java.lang.Object
HashMap
.
The general contract of hashCode
is:
hashCode
method
must consistently return the same integer, provided no information
used in equals
comparisons on the object is modified.
This integer need not remain consistent from one execution of an
application to another execution of the same application.
equals(Object)
method, then calling the hashCode
method on each of
the two objects must produce the same integer result.
Object.equals(java.lang.Object)
method, then calling the hashCode
method on each of the
two objects must produce distinct integer results. However, the
programmer should be aware that producing distinct integer results
for unequal objects may improve the performance of hash tables.
As much as is reasonably practical, the hashCode method defined by
class Object
does return distinct integers for distinct
objects. (This is typically implemented by converting the internal
address of the object into an integer, but this implementation
technique is not required by the
Java™ programming language.)
hashCode
in interface Graph<N>
hashCode
in class Object
Object.equals(java.lang.Object)
,
System.identityHashCode(java.lang.Object)
protected long edgeCount()
edges()
. This
implementation requires O(N) time. Classes extending this one may manually keep track of the
number of edges as the graph is updated, and override this method for better performance.public Set<EndpointPair<N>> edges()
public Set<EndpointPair<N>> incidentEdges(N node)
node
.
This is equal to the union of incoming and outgoing edges.
public int degree(N node)
node
's incident edges, counting selfloops twice (equivalently,
the number of times an edge touches node
).
For directed graphs, this is equal to inDegree(node) + outDegree(node)
.
For undirected graphs, 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
.
public int inDegree(N node)
node
's incoming edges (equal to predecessors(node).size()
)
in a directed graph. In an undirected graph, returns the degree(Object)
.
If the count is greater than Integer.MAX_VALUE
, returns Integer.MAX_VALUE
.
public int outDegree(N node)
node
's outgoing edges (equal to successors(node).size()
)
in a directed graph. In an undirected graph, returns the degree(Object)
.
If the count is greater than Integer.MAX_VALUE
, returns Integer.MAX_VALUE
.
public boolean hasEdgeConnecting(N nodeU, N nodeV)
nodeU
to nodeV
. This is
equivalent to nodes().contains(nodeU) && successors(nodeU).contains(nodeV)
.
In an undirected graph, this is equal to hasEdgeConnecting(nodeV, nodeU)
.
public boolean hasEdgeConnecting(EndpointPair<N> endpoints)
endpoints
(in the order, if
any, specified by endpoints
). This is equivalent to edges().contains(endpoints)
.
Unlike the other EndpointPair
accepting methods, this method does not throw if the
endpoints are unordered; it simply returns false. This is for consistency with the behavior of
Collection#contains(Object)
(which does not generally throw if the object cannot be
present in the collection), and the desire to have this method's behavior be compatible with
edges().contains(endpoints)
.
protected final void validateEndpoints(EndpointPair<?> endpoints)
IllegalArgumentException
if the ordering of endpoints
is not compatible
with the directionality of this graph.protected final boolean isOrderingCompatible(EndpointPair<?> endpoints)
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