Create GraphImplementation.java

Java/Algorithms/Graphs/GraphImplementation.java

@@ -0,0 +1,119 @@
+import java.util.*;   
+class Graph<T>   
+{   
+//creating an object of the Map class that stores the edges of the graph  
+private Map<T, List<T> > map = new HashMap<>();   
+//the method adds a new vertex to the graph  
+public void addNewVertex(T s)   
+{   
+map.put(s, new LinkedList<T>());   
+}   
+//the method adds an edge between source and destination   
+public void addNewEdge(T source, T destination, boolean bidirectional)   
+{   
+//      
+if (!map.containsKey(source))   
+addNewVertex(source);   
+if (!map.containsKey(destination))   
+addNewVertex(destination);   
+map.get(source).add(destination);   
+if (bidirectional == true)   
+{   
+map.get(destination).add(source);   
+}   
+}   
+//the method counts the number of vertices  
+public void countVertices()   
+{   
+System.out.println("Total number of vertices: "+ map.keySet().size());   
+}   
+//the method counts the number of edges  
+public void countEdges(boolean bidirection)   
+{   
+//variable to store number of edges      
+int count = 0;   
+for (T v : map.keySet())   
+{   
+count = count + map.get(v).size();   
+}   
+if (bidirection == true)   
+{   
+count = count / 2;   
+}   
+System.out.println("Total number of edges: "+ count);   
+}   
+//checks a graph has vertex or not  
+public void containsVertex(T s)   
+{   
+if (map.containsKey(s))   
+{   
+System.out.println("The graph contains "+ s + " as a vertex.");   
+}   
+else   
+{   
+System.out.println("The graph does not contain "+ s + " as a vertex.");   
+}   
+}   
+//checks a graph has edge or not  
+//where s and d are the two parameters that represent source(vertex) and destination (vertex)  
+public void containsEdge(T s, T d)   
+{   
+if (map.get(s).contains(d))   
+{   
+System.out.println("The graph has an edge between "+ s + " and " + d + ".");   
+}   
+else   
+{   
+System.out.println("There is no edge between "+ s + " and " + d + ".");   
+}   
+}   
+//prints the adjacencyS list of each vertex  
+//here we have overridden the toString() method of the StringBuilder class  
+@Override  
+public String toString()   
+{   
+StringBuilder builder = new StringBuilder();   
+//foreach loop that iterates over the keys  
+for (T v : map.keySet())   
+{   
+builder.append(v.toString() + ": ");   
+//foreach loop for getting the vertices  
+for (T w : map.get(v))   
+{   
+builder.append(w.toString() + " ");   
+}   
+builder.append("\n");   
+}   
+return (builder.toString());   
+}   
+}   
+//creating a class in which we have implemented the driver code  
+public class GraphImplementation  
+{   
+public static void main(String args[])   
+{   
+//creating an object of the Graph class  
+Graph graph=new Graph();  
+//adding edges to the graph  
+graph.addNewEdge(0, 1, true);   
+graph.addNewEdge(0, 4, true);   
+graph.addNewEdge(1, 2, true);   
+graph.addNewEdge(1, 3, false);   
+graph.addNewEdge(1, 4, true);   
+graph.addNewEdge(2, 3, true);   
+graph.addNewEdge(2, 4, true);   
+graph.addNewEdge(3, 0, true);   
+graph.addNewEdge(2, 0, true);   
+//prints the adjacency matrix that represents the graph  
+System.out.println("Adjacency List for the graph:\n"+ graph.toString());   
+//counts the number of vertices in the graph   
+graph.countVertices();   
+//counts the number of edges in the graph   
+graph.countEdges(true);   
+//checks whether an edge is present or not between the two specified vertices  
+graph.containsEdge(3, 4);   
+graph.containsEdge(2, 4);   
+//checks whether vertex is present or not   
+graph.containsVertex(3);   
+graph.containsVertex(5);   
+}