structure
Class Edge<V,E>

java.lang.Object
  structure.Edge<V,E>

Direct Known Subclasses:

ComparableEdge

public class Edge<V,E>
extends java.lang.Object

A class implementing common edge type among graphs. This class supports both directed and undirected edges. Edge may also have visited flags set and cleared.

Typical usage:

     Graph g = new GraphListDirected();
     g.add("harry");
     g.add("sally");
     g.addEdge("harry","sally","friendly");
     Edge e = g.getEdge("harry","sally");
     Object label = e.label();
     if(e.isDirected()){
          Vertex source = e.here();
          Vertex destination = e.there();
     }
     e.visit();
     e.reset();
     ...
 

See Also:

Graph

Constructor Summary

Edge(V vtx1, V vtx2, E label, boolean directed)
Construct a (possibly directed) edge between two labeled vertices.

Method Summary

boolean	equals(java.lang.Object o) Test for equality of edges.
int	hashCode() Returns hashcode associated with edge.
V	here() Returns the first vertex (or source if directed).
boolean	isDirected() Check to see if edge is directed.
boolean	isVisited() Check to see if edge has been visited.
E	label() Get label associated with edge.
void	reset() Clear the visited flag associated with edge.
void	setLabel(E label) Sets the label associated with the edge.
V	there() Returns the second vertex (or source if undirected).
java.lang.String	toString() Construct a string representation of edge.
boolean	visit() Test and set visited flag on vertex.

Methods inherited from class java.lang.Object

getClass, notify, notifyAll, wait, wait, wait

Constructor Detail

Edge

public Edge(V vtx1,
            V vtx2,
            E label,
            boolean directed)

Construct a (possibly directed) edge between two labeled vertices. When edge is directed, vtx1 specifies source. When undirected, order of vertices is unimportant. Label on edge is any type, and may be null. Edge is initially unvisited.

Parameters:

vtx1 - The label of a vertex (source if directed).

vtx2 - The label of another vertex (destination if directed).

label - The label associated with the edge.

directed - True iff this edge is directed.

Post:

edge associates vtx1 and vtx2; labeled with label directed if "directed" set true

Method Detail

here

public V here()

Returns the first vertex (or source if directed).

Returns:

A vertex; if directed, the source.

Post:

returns first node in edge

there

public V there()

Returns the second vertex (or source if undirected).

Returns:

A vertex; if directed, the destination.

Post:

returns second node in edge

setLabel

public void setLabel(E label)

Sets the label associated with the edge. May be null.

Parameters:

label - Any object to label edge, or null.

Post:

sets label of this edge to label

label

public E label()

Get label associated with edge.

Returns:

The label found on the edge.

Post:

returns label associated with this edge

visit

public boolean visit()

Test and set visited flag on vertex.

Returns:

True iff edge was visited previously.

Post:

visits edge, returns whether previously visited

isVisited

public boolean isVisited()

Check to see if edge has been visited.

Returns:

True iff the edge has been visited.

Post:

returns true iff edge has been visited

isDirected

public boolean isDirected()

Check to see if edge is directed.

Returns:

True iff the edge has been visited.

Post:

returns true iff edge is directed

reset

public void reset()

Clear the visited flag associated with edge.

Post:

resets edge's visited flag to initial state

hashCode

public int hashCode()

Returns hashcode associated with edge.

Overrides:

hashCode in class java.lang.Object

Returns:

An integer code suitable for hashing.

Post:

returns suitable hashcode

equals

public boolean equals(java.lang.Object o)

Test for equality of edges. Undirected edges are equal if they connect the same vertices. Directed edges must have same direction.

Overrides:

equals in class java.lang.Object

Parameters:

o - The other edge.

Returns:

True iff this edge is equal to other edge.

Post:

returns true iff edges connect same vertices

toString

public java.lang.String toString()

Construct a string representation of edge.

Overrides:

toString in class java.lang.Object

Returns:

String representing edge.

Post:

returns string representation of edge