org.jgrapht.alg

Class CycleDetector<V,E>

java.lang.Object

org.jgrapht.alg.CycleDetector<V,E>

public class CycleDetector<V,E>
extends Object

Performs cycle detection on a graph. The inspected graph is specified at construction time and cannot be modified. Currently, the detector supports only directed graphs.

Since:

Sept 16, 2004

Author:

John V. Sichi

Constructor Summary

Constructors

Constructor and Description
CycleDetector(DirectedGraph<V,E> graph) Creates a cycle detector for the specified graph.

Method Summary

Methods

Modifier and Type	Method and Description
boolean	detectCycles() Performs yes/no cycle detection on the entire graph.
boolean	detectCyclesContainingVertex(V v) Performs yes/no cycle detection on an individual vertex.
Set<V>	findCycles() Finds the vertex set for the subgraph of all cycles.
Set<V>	findCyclesContainingVertex(V v) Finds the vertex set for the subgraph of all cycles which contain a particular vertex.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

CycleDetector

public CycleDetector(DirectedGraph<V,E> graph)

Creates a cycle detector for the specified graph. Currently only directed graphs are supported.

Parameters:

graph - the DirectedGraph in which to detect cycles

Method Detail

detectCycles

public boolean detectCycles()

Performs yes/no cycle detection on the entire graph.

Returns:

true iff the graph contains at least one cycle

detectCyclesContainingVertex

public boolean detectCyclesContainingVertex(V v)

Performs yes/no cycle detection on an individual vertex.

Parameters:

v - the vertex to test

Returns:

true if v is on at least one cycle

findCycles

public Set<V> findCycles()

Finds the vertex set for the subgraph of all cycles.

Returns:

set of all vertices which participate in at least one cycle in this graph

findCyclesContainingVertex

public Set<V> findCyclesContainingVertex(V v)

Finds the vertex set for the subgraph of all cycles which contain a particular vertex.

REVIEW jvs 25-Aug-2006: This implementation is not guaranteed to cover all cases. If you want to be absolutely certain that you report vertices from all cycles containing v, it's safer (but less efficient) to use StrongConnectivityAlgorithm instead and return the strongly connected component containing v.

Parameters:

v - the vertex to test

Returns:

set of all vertices reachable from v via at least one cycle