Graph

package lab;// IMPORTS /* * A common interface for the Graph ADT, encompassing directed and undirected weighted graphs with integer weights. * The vertex are represented by natural numbers (e.g. 0,1,2,3...), and remain the same after the creation * of an instance of a Graph. Therefore, no vertex can be added or removed after the creation of the graph instance. * The same occurs with the characteristic of being directed or not. A graph can not change this characteristic * after its creation. * Self-loops are allowed. * Any method that takes one or more vertex IDs as arguments must throw an IndexOutOfBoundsException * if any input ID is out of bounds. An error message explaining that the vertex does not exist must appear in the screen. */ import lab.components.Edge; import lab.components.Vertex; import java.util.List; public interface Graph { // 1. ABSTRACT METHOD numVerts: Returns the number of vertices in the graph. public abstract int numVerts(); /* * 2. ABSTRACT METHOD numEdges: Returns the number of edges in the graph. * The result does *not* double-count edges in undirected graphs. */ public abstract int numEdges(); /* * 3. ABSTRACT METHOD addEdge: Adds and Edge between vertex v1 and v2 with weight w. * If the edge v1 and v2 already exists with a different weight, it modifies the weight to w. * In undirected graphs both directions of the edge must be represented. */ public abstract boolean addEdge(Vertex v1, Vertex v2, int weight); /* * 4. ABSTRACT METHOD removeEdge: Removes an edge between vertex v1 and v2. * Remember that in undirected graphs both directions of the edge must be removed. */ public abstract boolean removeEdge(Vertex v1, Vertex v2, int weight); /* * 5. ABSTRACT METHOD hasEdge: Checks whether an edge exists between two vertices. * In directed graphs returns true if there is a vertex from a vertex v1 to a vertex v2. * In an undirected graph, this method returns the same as hasEdge from vertex v2 to v1 (opposite order). */ public abstract boolean hasEdge(Vertex v1, Vertex v2); /* * 6. ABSTRACT METHOD getWeightEdge: Returns the weight an edge (if exists) between two vertices. * If it does not exist, it prints an error message in the screen. * In directed graphs returns the weight of the edge from the vertex v1 to a vertex v2. * In an undirected graph, this method returns the same as getWeightEdge from vertex v2 to v1 (opposite order). */ public abstract int getWeightEdge(Vertex v1, Vertex v2); /* * 7. ABSTRACT METHOD getNeighbors: Returns a List of the neighbors of * the specified vertex v (equivalent to the out-degree/out-edges of the vertex v. * In particular, the vertex u is included in the list if and only if there is an edge from v to u in the graph. */ public abstract List<Edge> getNeighbors(Vertex v); /* * 8. ABSTRACT METHOD getDegree: Returns the degree of the specified vertex v. * In undirected graphs the degree is equal to the sum of the in-degree and the out-degree * The result does *not* double-count edges in undirected graphs. */ public abstract int getDegree(Vertex v); // 9. ABSTRACT METHOD toString: The method is used to get a String object representing the graph. //You have freedom for representing the string that describes the graph, but it should contain: // all its vertices, all its edges and their weights. public abstract String toSting(); }