DirectedEdge (Algorithms 4/e)

Object
- edu.princeton.cs.algs4.DirectedEdge

```
public class DirectedEdge
extends Object
```
The DirectedEdge class represents a weighted edge in an EdgeWeightedDigraph. 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 directed edge and the weight.
For additional documentation, see Section 4.4 of Algorithms, 4th Edition by Robert Sedgewick and Kevin Wayne.

Author:

Robert Sedgewick, Kevin Wayne

Constructor Summary

Constructors
Constructor Description

DirectedEdge(int v, int w, double weight)
Initializes a directed edge from vertex v to vertex w with the given weight.

Method Summary

All Methods Static Methods Instance Methods Concrete Methods
Modifier and Type	Method	Description
`int`	`from()`	Returns the tail vertex of the directed edge.
`static void`	`main(String[] args)`	Unit tests the `DirectedEdge` data type.
`int`	`to()`	Returns the head vertex of the directed edge.
`String`	`toString()`	Returns a string representation of the directed edge.
`double`	`weight()`	Returns the weight of the directed edge.

Methods inherited from class java.lang.Object
clone, equals, getClass, hashCode, notify, notifyAll, wait, wait, wait

- Constructor Detail
  - DirectedEdge
```
public DirectedEdge(int v,
                    int w,
                    double weight)
```
    Initializes a directed edge from vertex v to vertex w with the given weight.
    
    Parameters:
    
    v - the tail vertex
    
    w - the head vertex
    
    weight - the weight of the directed edge
    
    Throws:
    
    IllegalArgumentException - if either v or w is a negative integer
    
    IllegalArgumentException - if weight is NaN
- Method Detail
  - from
```
public int from()
```
    Returns the tail vertex of the directed edge.
    
    Returns:
    
    the tail vertex of the directed edge
  - to
```
public int to()
```
    Returns the head vertex of the directed edge.
    
    Returns:
    
    the head vertex of the directed edge
  - weight
```
public double weight()
```
    Returns the weight of the directed edge.
    
    Returns:
    
    the weight of the directed edge
  - toString
```
public String toString()
```
    Returns a string representation of the directed edge.
    
    Overrides:
    
    toString in class Object
    
    Returns:
    
    a string representation of the directed edge
  - main
```
public static void main(String[] args)
```
    Unit tests the DirectedEdge data type.
    
    Parameters:
    
    args - the command-line arguments