Package edu.princeton.cs.algs4

Class Edge

Object

edu.princeton.cs.algs4.Edge

All Implemented Interfaces:

Comparable<Edge>

public class Edge
extends Object
implements Comparable<Edge>

The Edge class represents a weighted edge in an EdgeWeightedGraph. Each edge consists of two integers (naming the two vertices) and a real-value weight. The data type provides methods for accessing the two endpoints of the edge and the weight. The natural order for this data type is by ascending order of weight.

For additional documentation, see Section 4.3 of Algorithms, 4th Edition by Robert Sedgewick and Kevin Wayne.

Author:

Robert Sedgewick, Kevin Wayne

Constructor Summary

Constructors

Constructor	Description
Edge(int v, int w, double weight)	Initializes an edge between vertices v and w of the given weight.

Method Summary

Modifier and Type	Method	Description
int	compareTo(Edge that)	Compares two edges by weight.
int	either()	Returns either endpoint of this edge.
static void	main(String[] args)	Unit tests the Edge data type.
int	other(int vertex)	Returns the endpoint of this edge that is different from the given vertex.
String	toString()	Returns a string representation of this edge.
double	weight()	Returns the weight of this edge.

Methods inherited from class java.lang.Object

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

Constructor Detail

Edge

public Edge(int v,
            int w,
            double weight)

Initializes an edge between vertices v and w of the given weight.

Parameters:

v - one vertex

w - the other vertex

weight - the weight of this edge

Throws:

IllegalArgumentException - if either v or w is a negative integer

IllegalArgumentException - if weight is NaN

Method Detail

weight

public double weight()

Returns the weight of this edge.

Returns:

the weight of this edge

either

public int either()

Returns either endpoint of this edge.

Returns:

either endpoint of this edge

other

public int other(int vertex)

Returns the endpoint of this edge that is different from the given vertex.

Parameters:

vertex - one endpoint of this edge

Returns:

the other endpoint of this edge

Throws:

IllegalArgumentException - if the vertex is not one of the endpoints of this edge

compareTo

public int compareTo(Edge that)

Compares two edges by weight. Note that compareTo() is not consistent with equals(), which uses the reference equality implementation inherited from Object.

Specified by:

compareTo in interface Comparable<Edge>

Parameters:

that - the other edge

Returns:

a negative integer, zero, or positive integer depending on whether the weight of this is less than, equal to, or greater than the argument edge

toString

public String toString()

Returns a string representation of this edge.

Overrides:

toString in class Object

Returns:

a string representation of this edge

main

public static void main(String[] args)

Unit tests the Edge data type.

Parameters:

args - the command-line arguments