ptolemy.graph
Class Edge

java.lang.Object
  ptolemy.graph.Element
      ptolemy.graph.Edge

public final class Edge
extends Element

A weighted or unweighted edge for a directed or undirected graph. The connectivity of edges is specified by source nodes and sink nodes. A directed edge is directed from its source node to its sink node. For an undirected edge, the source node is simply the first node that was specified when the edge was created, and the sink node is the second node. This convention allows undirected edges to later be converted in a consistent manner to directed edges, if desired.

On creation of an edge, an arbitrary object can be associated with the edge as the weight of the edge. We say that an edge is unweighted if it does not have an assigned weight. It is an error to attempt to access the weight of an unweighted edge.

Self-loop edges (edges whose source and sink nodes are identical) are allowed.

Once an edge is created, its source node and sink node cannot be changed.

Since:

Ptolemy II 2.0

Version:

$Id: Edge.java 38798 2005-07-08 20:00:01Z cxh $

Author:

Shuvra S. Bhattacharyya

See Also:

Node

Accepted Rating:

Red (cxh)

Proposed Rating:

Red (cxh)

Field Summary

private Node	_sink
private Node	_source

Fields inherited from class ptolemy.graph.Element

_weight

Constructor Summary

Edge(Node source, Node sink)
Construct an unweighted edge with a specified source node and sink node.

Edge(Node source, Node sink, java.lang.Object weight)
Construct a weighted edge with a specified source node, sink node, and edge weight.

Method Summary

java.lang.String	descriptor() A one-word description of the type of this graph element.
boolean	isSelfLoop() Return true if this is a self-loop edge.
Node	sink() Return the sink node of the edge.
Node	source() Return the source node of the edge.
java.lang.String	toString() Return a string representation of the edge, including information about the edge weight.
java.lang.String	toString(boolean showWeight) Return a string representation of the edge, optionally including information about the edge weight.

Methods inherited from class ptolemy.graph.Element

getWeight, hasWeight, removeWeight, setWeight

Methods inherited from class java.lang.Object

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

Field Detail

_sink

private Node _sink

_source

private Node _source

Constructor Detail

Edge

public Edge(Node source,
            Node sink)

Construct an unweighted edge with a specified source node and sink node.

Parameters:

source - The source node.

sink - The sink node.

Edge

public Edge(Node source,
            Node sink,
            java.lang.Object weight)

Construct a weighted edge with a specified source node, sink node, and edge weight.

Parameters:

source - The source node.

sink - The sink node.

weight - The edge weight.

Throws:

java.lang.IllegalArgumentException - If the specified weight is null.

Method Detail

descriptor

public java.lang.String descriptor()

A one-word description of the type of this graph element.

Overrides:

descriptor in class Element

Returns:

The description.

isSelfLoop

public boolean isSelfLoop()

Return true if this is a self-loop edge.

Returns:

True if this is a self-loop edge.

sink

public Node sink()

Return the sink node of the edge.

Returns:

The sink node.

source

public Node source()

Return the source node of the edge.

Returns:

The source node.

toString

public java.lang.String toString(boolean showWeight)

Return a string representation of the edge, optionally including information about the edge weight. The string representation is of the form

(source, sink, weight),

where source, sink, and weight are string representations of the source node, sink node, and edge weight, respectively. If the edge is unweighted or the showWeight argument is false, then the string representation is simply

(source, sink).

Parameters:

showWeight - True to include a string representation of the edge weight in the string representation of the edge.

Returns:

A string representation of the edge.

toString

public java.lang.String toString()

Return a string representation of the edge, including information about the edge weight.

Overrides:

toString in class java.lang.Object

Returns:

A string representation of the edge.

See Also:

toString(boolean)