Graph

All Known Implementing Classes:

BasicGraph
```
public interface Graph<V,E>
```
A Graph is a collection of vertices and edges between vertices. A graph can be directed or undirected (indicating whether edges are one-directional or bidirectional, respectively), and weighted or unweighted (indicating whether edges have different or uniform cost, respectively).
A Graph does not allow null vertices, but it does allow null edges, which corresponds to an edge with no extra information stored in it.
A Graph can have at most one edge with the same start and end vertex; in other words, it is not permitted to have two edges between the same vertices, except in a directed graph it is allowed to have an edge A,B and an edge B,A. Loops (edges from a vertex directly back to itself) are prohibited; an IllegalArgumentException will be thrown on an attempt to add a loop.
Implementations of the Graph interface do not allow edges with negative weights. If a negative edge weight is passed, an IllegalArgumentException is thrown. A weight of 0 is allowed.

Method Summary

All Methods Instance Methods Abstract Methods
Modifier and Type	Method and Description
`void`	`addEdge(String v1, String v2)` Adds an edge between the given two vertices, if none already exists.
`void`	`addEdge(String v1, String v2, double weight)` Adds an edge between the given two vertices, if none already exists.
`void`	`addEdge(Vertex<V> v1, Vertex<V> v2)` Adds an edge between the given two vertices, if none already exists.
`void`	`addEdge(Vertex<V> v1, Vertex<V> v2, double weight)` Adds an edge between the given two vertices, if none already exists.
`void`	`addVertex(String v)` Adds the given element as a vertex in this graph.
`void`	`clear()` Removes all vertices and edges from this graph.
`void`	`clearEdges()` Removes all edges from this graph.
`boolean`	`containsEdge(String v1, String v2)` Returns whether this graph contains an edge between the given vertices.
`boolean`	`containsEdge(Vertex<V> v1, Vertex<V> v2)` Returns whether this graph contains an edge between the given vertices.
`boolean`	`containsPath(List<String> path)` Returns true if the given list of vertices represents a path that can be formed by walking edges between those vertices in this graph, walking from the start to the end of the list.
`boolean`	`containsVertex(String v)` Returns whether this graph contains the given vertex.
`boolean`	`containsVertex(Vertex<V> v)` Returns whether this graph contains the given vertex.
`double`	`cost(List<String> path)` Returns the total cost of following the given path of vertices in this graph, which is the sum of the edge weights between the path's vertices from start to end.
`int`	`degree(String v)` Returns the number of outgoing edges from the given vertex.
`int`	`degree(Vertex<V> v)` Returns the number of outgoing edges from the given vertex.
`Edge<V,E>`	`edge(String v1, String v2)` Returns the extra information stored in the edge between vertices v1 and v2, if one exists.
`Edge<V,E>`	`edge(Vertex<V> v1, Vertex<V> v2)` Returns the extra information stored in the edge between vertices v1 and v2, if one exists.
`int`	`edgeCount()` Returns the total number of edges in this graph.
`Collection<Edge<V,E>>`	`edges()` Returns a collection of all edges in this graph.
`double`	`edgeWeight(String v1, String v2)` Returns the weight of the edge between vertices v1 and v2, if one exists.
`double`	`edgeWeight(Vertex<V> v1, Vertex<V> v2)` Returns the weight of the edge between vertices v1 and v2, if one exists.
`int`	`inDegree(String v)` Returns the number of incoming edges to the given vertex.
`int`	`inDegree(Vertex<V> v)` Returns the number of incoming edges to the given vertex.
`boolean`	`isDirected()` Returns true if this is a directed graph, and false if it is undirected.
`boolean`	`isEmpty()` Returns true if this graph does not contain any vertices or edges.
`boolean`	`isWeighted()` Returns true if this is a weighted graph and false if it is unweighted.
`Set<Vertex<V>>`	`neighbors(String v)` Returns a collection containing all neighbors, that is, all vertices that are directly connected to the given vertex by an outgoing edge.
`Set<Vertex<V>>`	`neighbors(Vertex<V> v)` Returns a collection containing all neighbors, that is, all vertices that are directly connected to the given vertex by an outgoing edge.
`int`	`outDegree(String v)` Returns the number of outgoing edges from the given vertex.
`int`	`outDegree(Vertex<V> v)` Returns the number of outgoing edges from the given vertex.
`void`	`removeEdge(Edge<V,E> e)` Removes any edge(s) that exist with the given extra info stored in it/them.
`void`	`removeEdge(String v1, String v2)` Removes any edge that exists from vertex v1 to vertex v2.
`void`	`removeEdge(Vertex<V> v1, Vertex<V> v2)` Removes any edge that exists from vertex v1 to vertex v2.
`void`	`removeVertex(String v)` Removes the given vertex from this graph, along with all edges that were touching it.
`void`	`removeVertex(Vertex<V> v)` Removes the given vertex from this graph, along with all edges that were touching it.
`void`	`resetData()` Clears out any data stored in each vertex.
`String`	`toString()` Returns a string representation of this graph and its vertices and edges, such as "{V={A, B, C}, E={(A, B), (A, C)}}".
`String`	`toStringDetailed()` Returns a detailed multi-line string representation of this graph and its vertices, such as "Graph{ vertices: A -> neighbors: [B, C] B -> neighbors: [A] C -> neighbors: [A] edges: (A,B,weight=2) (A,C) }"
`Vertex<V>`	`vertex(String name)` Returns the structure of information about the vertex with the given name.
`int`	`vertexCount()` Returns the number of vertices in this graph.
`Collection<Vertex<V>>`	`vertexes()` Returns a collection of the vertices in this graph.

- Method Detail
  - addEdge
```
void addEdge(String v1,
             String v2)
```
    Adds an edge between the given two vertices, if none already exists. The edge will be given a default weight of 1. No extra information will be stored in the edge. If an edge already exists between these vertices, its extra information will be cleared and its weight is updated to 1. If this graph is undirected, the two vertices can be passed in either order.
    
    Parameters:
    
    v1 - Starting vertex.
    
    v2 - Ending vertex.
    
    Throws:
    
    IllegalArgumentException - If either vertex is not part of the graph, or if v1 and v2 are the same (a loop).
    
    NullPointerException - If any object parameter is null.
  - addEdge
```
void addEdge(Vertex<V> v1,
             Vertex<V> v2)
```
    Adds an edge between the given two vertices, if none already exists. The edge will be given a default weight of 1. No extra information will be stored in the edge. If an edge already exists between these vertices, its extra information will be cleared and its weight is updated to 1. If this graph is undirected, the two vertices can be passed in either order.
    
    Parameters:
    
    v1 - Starting vertex.
    
    v2 - Ending vertex.
    
    Throws:
    
    IllegalArgumentException - If either vertex is not part of the graph, or if v1 and v2 are the same (a loop).
    
    NullPointerException - If any object parameter is null.
  - addEdge
```
void addEdge(String v1,
             String v2,
             double weight)
```
    Adds an edge between the given two vertices, if none already exists. The edge will be given a default weight of 1. No extra information will be stored in the edge. If an edge already exists between these vertices, its extra information will be cleared and its weight is updated to 1. If this graph is undirected, the two vertices can be passed in either order.
    
    Parameters:
    
    v1 - Starting vertex.
    
    v2 - Ending vertex.
    
    weight - Edge's weight.
    
    Throws:
    
    IllegalArgumentException - If either vertex is not part of the graph, if edge weight is negative, if v1 and v2 are the same (a loop), or if this is an unweighted graph and an edge weight other than 1 is passed.
    
    NullPointerException - If any object parameter is null.
  - addEdge
```
void addEdge(Vertex<V> v1,
             Vertex<V> v2,
             double weight)
```
    Adds an edge between the given two vertices, if none already exists. The edge will be given a default weight of 1. No extra information will be stored in the edge. If an edge already exists between these vertices, its extra information will be cleared and its weight is updated to 1. If this graph is undirected, the two vertices can be passed in either order.
    
    Parameters:
    
    v1 - Starting vertex.
    
    v2 - Ending vertex.
    
    weight - Edge's weight.
    
    Throws:
    
    IllegalArgumentException - If either vertex is not part of the graph, if edge weight is negative, if v1 and v2 are the same (a loop), or if this is an unweighted graph and an edge weight other than 1 is passed.
    
    NullPointerException - If any object parameter is null.
  - addVertex
```
void addVertex(String v)
```
    Adds the given element as a vertex in this graph. If the given element is already a vertex in this graph, no change is made.
    
    Parameters:
    
    v - The vertex to add.
    
    Throws:
    
    NullPointerException - If the vertex is null.
  - clear
```
void clear()
```
    Removes all vertices and edges from this graph.
  - clearEdges
```
void clearEdges()
```
    Removes all edges from this graph.
  - containsEdge
```
boolean containsEdge(String v1,
                     String v2)
```
    Returns whether this graph contains an edge between the given vertices. If either vertex is not part of this graph, returns false.
  - containsEdge
```
boolean containsEdge(Vertex<V> v1,
                     Vertex<V> v2)
```
    Returns whether this graph contains an edge between the given vertices. If either vertex is not part of this graph, returns false.
  - containsPath
```
boolean containsPath(List<String> path)
```
    Returns true if the given list of vertices represents a path that can be formed by walking edges between those vertices in this graph, walking from the start to the end of the list. If any vertex in the path is not found in this graph, or if there is not an edge between any pair of neighboring vertices in the list, returns false. Returns true for an empty list, and for a one-element list where the one element is a vertex that is found in this graph.
    
    Parameters:
    
    path - The list of vertices representing the path to check.
    
    Throws:
    
    NullPointerException - If the list or any of its elements is null.
  - containsVertex
```
boolean containsVertex(String v)
```
    Returns whether this graph contains the given vertex. If the vertex passed is null, returns false.
    
    Parameters:
    
    v - The vertex.
  - containsVertex
```
boolean containsVertex(Vertex<V> v)
```
    Returns whether this graph contains the given vertex. If the vertex passed is null, returns false.
    
    Parameters:
    
    v - The vertex.
  - cost
```
double cost(List<String> path)
```
    Returns the total cost of following the given path of vertices in this graph, which is the sum of the edge weights between the path's vertices from start to end.
    
    Parameters:
    
    path - The list of vertices in the path to examine.
    
    Throws:
    
    IllegalArgumentException - If any vertex in the path is not part of this graph, or if there is not an edge between any two neighboring vertices in the path.
    
    NullPointerException - If the path or any vertex in it is null.
  - degree
```
int degree(String v)
```
    Returns the number of outgoing edges from the given vertex. This method is an alias for outDegree; it is provided because undirected graphs generally just think of vertices as having one overall degree and not a separate in- and out- degree.
    
    Parameters:
    
    v - The vertex.
    
    Throws:
    
    IllegalArgumentException - If the vertex is not part of the graph.
    
    NullPointerException - If any object parameter is null.
  - degree
```
int degree(Vertex<V> v)
```
    Returns the number of outgoing edges from the given vertex. This method is an alias for outDegree; it is provided because undirected graphs generally just think of vertices as having one overall degree and not a separate in- and out- degree.
    
    Parameters:
    
    v - The vertex.
    
    Throws:
    
    IllegalArgumentException - If the vertex is not part of the graph.
    
    NullPointerException - If any object parameter is null.
  - edge
```
Edge<V,E> edge(String v1,
               String v2)
```
    Returns the extra information stored in the edge between vertices v1 and v2, if one exists. If this graph is undirected, the two vertices can be passed in either order. Returns null if there is no edge between the given vertices or if the edge between the given vertices contains no extra information.
    
    Parameters:
    
    v1 - The starting vertex.
    
    v2 - The ending vertex.
    
    Throws:
    
    IllegalArgumentException - If either vertex is not part of the graph.
    
    NullPointerException - If any object parameter is null.
  - edge
```
Edge<V,E> edge(Vertex<V> v1,
               Vertex<V> v2)
```
    Returns the extra information stored in the edge between vertices v1 and v2, if one exists. If this graph is undirected, the two vertices can be passed in either order. Returns null if there is no edge between the given vertices or if the edge between the given vertices contains no extra information.
    
    Parameters:
    
    v1 - The starting vertex.
    
    v2 - The ending vertex.
    
    Throws:
    
    IllegalArgumentException - If either vertex is not part of the graph.
    
    NullPointerException - If any object parameter is null.
  - edgeCount
```
int edgeCount()
```
    Returns the total number of edges in this graph. Note that this does not necessarily equal edges().size() because edges() returns a set of unique edge information values stored in each edge, excluding nulls (edges without any extra information stored in them), while this method returns a count of all edges including ones without any information stored in them and ones with information that is a duplicate of that stored in some other edge.
  - edges
```
Collection<Edge<V,E>> edges()
```
    Returns a collection of all edges in this graph. The collection is a shallow 'view' of the edges. Any changes made to it are written back to the graph. New edges cannot be added directly to the collection returned by this method, because it would not know which vertices to associate the edge with. But edges can be removed, cleared, etc.
  - edgeWeight
```
double edgeWeight(String v1,
                  String v2)
```
    Returns the weight of the edge between vertices v1 and v2, if one exists. If this graph is undirected, the two vertices can be passed in either order. Returns -1 if there is no edge between the given vertices.
    
    Parameters:
    
    v1 - The starting vertex.
    
    v2 - The ending vertex.
    
    Throws:
    
    IllegalArgumentException - If either vertex is not part of the graph.
    
    NullPointerException - If any object parameter is null.
  - edgeWeight
```
double edgeWeight(Vertex<V> v1,
                  Vertex<V> v2)
```
    Returns the weight of the edge between vertices v1 and v2, if one exists. If this graph is undirected, the two vertices can be passed in either order. Returns -1 if there is no edge between the given vertices.
    
    Parameters:
    
    v1 - The starting vertex.
    
    v2 - The ending vertex.
    
    Throws:
    
    IllegalArgumentException - If either vertex is not part of the graph.
    
    NullPointerException - If any object parameter is null.
  - inDegree
```
int inDegree(String v)
```
    Returns the number of incoming edges to the given vertex.
    
    Parameters:
    
    v - The vertex to examine.
    
    Throws:
    
    IllegalArgumentException - If the vertex is not part of the graph.
    
    NullPointerException - If any object parameter is null.
  - inDegree
```
int inDegree(Vertex<V> v)
```
    Returns the number of incoming edges to the given vertex.
    
    Parameters:
    
    v - The vertex to examine.
    
    Throws:
    
    IllegalArgumentException - If the vertex is not part of the graph.
    
    NullPointerException - If any object parameter is null.
  - isDirected
```
boolean isDirected()
```
    Returns true if this is a directed graph, and false if it is undirected.
  - isEmpty
```
boolean isEmpty()
```
    Returns true if this graph does not contain any vertices or edges.
  - isWeighted
```
boolean isWeighted()
```
    Returns true if this is a weighted graph and false if it is unweighted.
  - neighbors
```
Set<Vertex<V>> neighbors(String v)
```
    Returns a collection containing all neighbors, that is, all vertices that are directly connected to the given vertex by an outgoing edge. The collection is a shallow 'view' of the neighboring vertices. Any changes made to it are written back to the graph. New vertices cannot be added directly to the collection returned by this method. But vertices can be removed, cleared, etc.
    
    Parameters:
    
    v - The vertex to examine.
    
    Throws:
    
    IllegalArgumentException - If the vertex is not part of this graph.
    
    NullPointerException - If the vertex is null.
  - neighbors
```
Set<Vertex<V>> neighbors(Vertex<V> v)
```
    Returns a collection containing all neighbors, that is, all vertices that are directly connected to the given vertex by an outgoing edge. The collection is a shallow 'view' of the neighboring vertices. Any changes made to it are written back to the graph. New vertices cannot be added directly to the collection returned by this method. But vertices can be removed, cleared, etc.
    
    Parameters:
    
    v - The vertex to examine.
    
    Throws:
    
    IllegalArgumentException - If the vertex is not part of this graph.
    
    NullPointerException - If the vertex is null.
  - outDegree
```
int outDegree(String v)
```
    Returns the number of outgoing edges from the given vertex.
    
    Parameters:
    
    v - The vertex to examine.
  - outDegree
```
int outDegree(Vertex<V> v)
```
    Returns the number of outgoing edges from the given vertex.
    
    Parameters:
    
    v - The vertex to examine.
  - removeEdge
```
void removeEdge(Edge<V,E> e)
```
    Removes any edge(s) that exist with the given extra info stored in it/them. If multiple edges have the given extra info, all are removed. If null is passed, removes any edges that have no extra info stored in them. If no edge exists in this graph with the given extra info, has no effect. This implementation must examine all edges in the graph to find the specified edge, so it is inefficient.
    
    Parameters:
    
    e - The edge extra info of the edge to remove.
  - removeEdge
```
void removeEdge(String v1,
                String v2)
```
    Removes any edge that exists from vertex v1 to vertex v2. If this graph is undirected, the two vertices can be passed in either order. If no edge exists in this graph between the two given vertices, has no effect.
    
    Parameters:
    
    v1 - The starting vertex of the edge.
    
    v2 - The ending vertex of the edge.
    
    Throws:
    
    IllegalArgumentException - If either vertex is not part of the graph.
    
    NullPointerException - If any object parameter is null.
  - removeEdge
```
void removeEdge(Vertex<V> v1,
                Vertex<V> v2)
```
    Removes any edge that exists from vertex v1 to vertex v2. If this graph is undirected, the two vertices can be passed in either order. If no edge exists in this graph between the two given vertices, has no effect.
    
    Parameters:
    
    v1 - The starting vertex of the edge.
    
    v2 - The ending vertex of the edge.
    
    Throws:
    
    IllegalArgumentException - If either vertex is not part of the graph.
    
    NullPointerException - If any object parameter is null.
  - removeVertex
```
void removeVertex(String v)
```
    Removes the given vertex from this graph, along with all edges that were touching it. If the given vertex is not part of this graph, has no effect.
    
    Parameters:
    
    v - The vertex to remove.
    
    Throws:
    
    NullPointerException - If the vertex is null.
  - removeVertex
```
void removeVertex(Vertex<V> v)
```
    Removes the given vertex from this graph, along with all edges that were touching it. If the given vertex is not part of this graph, has no effect.
    
    Parameters:
    
    v - The vertex to remove.
    
    Throws:
    
    NullPointerException - If the vertex is null.
  - resetData
```
void resetData()
```
    Clears out any data stored in each vertex.
  - toString
```
String toString()
```
    Returns a string representation of this graph and its vertices and edges, such as "{V={A, B, C}, E={(A, B), (A, C)}}".
    
    Overrides:
    
    toString in class Object
  - toStringDetailed
```
String toStringDetailed()
```
    Returns a detailed multi-line string representation of this graph and its vertices, such as "Graph{ vertices: A -> neighbors: [B, C] B -> neighbors: [A] C -> neighbors: [A] edges: (A,B,weight=2) (A,C) }"
  - vertex
```
Vertex<V> vertex(String name)
```
    Returns the structure of information about the vertex with the given name.
  - vertexCount
```
int vertexCount()
```
    Returns the number of vertices in this graph.
  - vertexes
```
Collection<Vertex<V>> vertexes()
```
    Returns a collection of the vertices in this graph. The collection is a shallow 'view' of the vertices. Any changes made to it are written back to the graph. Vertices can be added, removed, cleared, etc. on this collection.

Interface Graph<V,E>

Method Summary

Method Detail

addEdge

addEdge

addEdge

addEdge

addVertex

clear

clearEdges

containsEdge

containsEdge

containsPath

containsVertex

containsVertex

cost

degree

degree

edge

edge

edgeCount

edges

edgeWeight

edgeWeight

inDegree

inDegree

isDirected

isEmpty

isWeighted

neighbors

neighbors

outDegree

outDegree

removeEdge

removeEdge

removeEdge

removeVertex

removeVertex

resetData

toString

toStringDetailed

vertex

vertexCount

vertexes