cs205 Data Abstraction Notes
(Repeated from Class 8)
public class Graph {
// OVERVIEW: A Graph is a mutable type that represents an undirected
// graph. It consists of nodes that are named by Strings,
// and edges that connect a pair of nodes.
// A typical Graph is: < Nodes, Edges > where
// Nodes = { n1, n2, , nm }
// and
// Edges = { {a_1, b_1}, ..., {a_n, b_n} }
// (note that the elements of Edges are unordered sets)
public Graph ()
// EFFECTS: Initializes this to a graph
// with no nodes or edges: < {}, {} >.
// Mutators
public void addNode (String name) throws DuplicateException
// MODIFIES: this
// EFFECTS: If name is in Nodes, throws DuplicateException.
// Otherwise, adds a node named name to this:
// this_post = < Nodes_pre U { name }, Edges_pre >
public void addEdge (String fnode, String tnode) throws
NoNodeException, DuplicateException
// MODIFIES: this
// EFFECTS: If s and t are not names of nodes in
// this, throws NoNodeException. If there is already an edge
// between s and t, throws DuplicateEdgeException.
// Otherwise, adds an edge between s and t to this:
// thispost = < Nodespre, Edgespre U {fnode, tnode} >
// Observers
public boolean hasNode (String node)
// EFFECTS: Returns true iff node is a node in this.
Set getNeighbors (String node)
// REQUIRES: node is a node in this
// EFFECTS: Returns the set consisting of all nodes in this
// that are directly connected to node:
// { n | {node, n} is in this.edges }
}