Package org.jgrapht.alg
Class DirectedNeighborIndex<V,E>
- java.lang.Object
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- org.jgrapht.alg.DirectedNeighborIndex<V,E>
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- All Implemented Interfaces:
java.util.EventListener
,GraphListener<V,E>
,VertexSetListener<V>
public class DirectedNeighborIndex<V,E> extends java.lang.Object implements GraphListener<V,E>
Maintains a cache of each vertex's neighbors. While lists of neighbors can be obtained fromGraphs
, they are re-calculated at each invocation by walking a vertex's incident edges, which becomes inordinately expensive when performed often.A vertex's neighbors are cached the first time they are asked for (i.e. the index is built on demand). The index will only be updated automatically if it is added to the associated graph as a listener. If it is added as a listener to a graph other than the one it indexes, results are undefined.
- Since:
- Dec 13, 2005
- Author:
- Charles Fry
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Constructor Summary
Constructors Constructor Description DirectedNeighborIndex(DirectedGraph<V,E> g)
Creates a neighbor index for the specified directed graph.
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Method Summary
All Methods Instance Methods Concrete Methods Modifier and Type Method Description void
edgeAdded(GraphEdgeChangeEvent<V,E> e)
Notifies that an edge has been added to the graph.void
edgeRemoved(GraphEdgeChangeEvent<V,E> e)
Notifies that an edge has been removed from the graph.java.util.List<V>
predecessorListOf(V v)
Returns the set of vertices which are the predecessors of a specified vertex.java.util.Set<V>
predecessorsOf(V v)
Returns the set of vertices which are the predecessors of a specified vertex.java.util.List<V>
successorListOf(V v)
Returns the set of vertices which are the successors of a specified vertex.java.util.Set<V>
successorsOf(V v)
Returns the set of vertices which are the successors of a specified vertex.void
vertexAdded(GraphVertexChangeEvent<V> e)
Notifies that a vertex has been added to the graph.void
vertexRemoved(GraphVertexChangeEvent<V> e)
Notifies that a vertex has been removed from the graph.
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Constructor Detail
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DirectedNeighborIndex
public DirectedNeighborIndex(DirectedGraph<V,E> g)
Creates a neighbor index for the specified directed graph.- Parameters:
g
- the graph for which a neighbor index is to be created.
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Method Detail
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predecessorsOf
public java.util.Set<V> predecessorsOf(V v)
Returns the set of vertices which are the predecessors of a specified vertex. The returned set is backed by the index, and will be updated when the graph changes as long as the index has been added as a listener to the graph.- Parameters:
v
- the vertex whose predecessors are desired- Returns:
- all unique predecessors of the specified vertex
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predecessorListOf
public java.util.List<V> predecessorListOf(V v)
Returns the set of vertices which are the predecessors of a specified vertex. If the graph is a multigraph, vertices may appear more than once in the returned list. Because a list of predecessors can not be efficiently maintained, it is reconstructed on every invocation by duplicating entries in the neighbor set. It is thus more efficient to usepredecessorsOf(Object)
unless duplicate neighbors are required.- Parameters:
v
- the vertex whose predecessors are desired- Returns:
- all predecessors of the specified vertex
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successorsOf
public java.util.Set<V> successorsOf(V v)
Returns the set of vertices which are the successors of a specified vertex. The returned set is backed by the index, and will be updated when the graph changes as long as the index has been added as a listener to the graph.- Parameters:
v
- the vertex whose successors are desired- Returns:
- all unique successors of the specified vertex
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successorListOf
public java.util.List<V> successorListOf(V v)
Returns the set of vertices which are the successors of a specified vertex. If the graph is a multigraph, vertices may appear more than once in the returned list. Because a list of successors can not be efficiently maintained, it is reconstructed on every invocation by duplicating entries in the neighbor set. It is thus more efficient to usesuccessorsOf(Object)
unless duplicate neighbors are required.- Parameters:
v
- the vertex whose successors are desired- Returns:
- all successors of the specified vertex
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edgeAdded
public void edgeAdded(GraphEdgeChangeEvent<V,E> e)
Description copied from interface:GraphListener
Notifies that an edge has been added to the graph.- Specified by:
edgeAdded
in interfaceGraphListener<V,E>
- Parameters:
e
- the edge event.- See Also:
GraphListener.edgeAdded(GraphEdgeChangeEvent)
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edgeRemoved
public void edgeRemoved(GraphEdgeChangeEvent<V,E> e)
Description copied from interface:GraphListener
Notifies that an edge has been removed from the graph.- Specified by:
edgeRemoved
in interfaceGraphListener<V,E>
- Parameters:
e
- the edge event.- See Also:
GraphListener.edgeRemoved(GraphEdgeChangeEvent)
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vertexAdded
public void vertexAdded(GraphVertexChangeEvent<V> e)
Description copied from interface:VertexSetListener
Notifies that a vertex has been added to the graph.- Specified by:
vertexAdded
in interfaceVertexSetListener<V>
- Parameters:
e
- the vertex event.- See Also:
VertexSetListener.vertexAdded(GraphVertexChangeEvent)
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vertexRemoved
public void vertexRemoved(GraphVertexChangeEvent<V> e)
Description copied from interface:VertexSetListener
Notifies that a vertex has been removed from the graph.- Specified by:
vertexRemoved
in interfaceVertexSetListener<V>
- Parameters:
e
- the vertex event.- See Also:
VertexSetListener.vertexRemoved(GraphVertexChangeEvent)
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