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

java.lang.Object
  extended by org.jgrapht.alg.CycleDetector<V,E>

public class CycleDetector<V,E>
extends java.lang.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
CycleDetector(DirectedGraph<V,E> graph)
          Creates a cycle detector for the specified graph.
 
Method Summary
 boolean detectCycles()
          Performs yes/no cycle detection on the entire graph.
 boolean detectCyclesContainingVertex(V v)
          Performs yes/no cycle detection on an individual vertex.
 java.util.Set<V> findCycles()
          Finds the vertex set for the subgraph of all cycles.
 java.util.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 java.util.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 java.util.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 StrongConnectivityInspector 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