Create graph using Jgraph

Question

I want to create a graph using Jgraph, and later use that graph to find the minimum spanning Tree.

How to create a graph using Jgraph?.

---

this is what I have implemented. Can you please tell me how to use kruskals algorithm from the package. I googled it, but couldn't find any information on it.

import org.jgrapht.*;
import org.jgrapht.graph.*;
public class MyGraph {
 UndirectedGraph<String, DefaultEdge> g = new SimpleGraph<String, DefaultEdge> (DefaultEdge.class);
 public void addVertex(String name) {
 // name=new String();
 g.addVertex(name);
 }
 public void addEdge(String v1,String v2) {
 g.addEdge(v1, v2);
 }
 public UndirectedGraph<String, DefaultEdge> getGraph() {
 return g;
 }
}

• yurib: whats jgraph? can you supply a link ? did you read the documentation/example code ?

Answer 1

This the main class where user input such as no of edges and vertices is taken to create a graph to the Spanning tree of the graph created. Below is the complete answer to this question.

import java.util.Scanner;
public class Main {
 public static void main(String args[]) {
 int x;
 Scanner sc=new Scanner(System.in);
 MyGraph my=new MyGraph();
 System.out.println("Enter the no of vertices");
 int no_of_ver=sc.nextInt();
 for(int i=1;i<=no_of_ver;i++) {
 System.out.println("Enter vertex"+i);
 my.addVertex(sc.next());
 }
 do {
 System.out.println("Enter the edges");
 String e1=sc.next();
 String e2=sc.next();
 my.addEdge(e1, e2);
 // my.setEdgeWeight();
 System.out.println("Continue... Yes:1 ********** No:0");
 x=sc.nextInt();
 } while(x==1);
 System.out.println("Graph\n"+my.getGraph().toString());
 System.out.println("\n\n**********Spanning Tree*********");
 my.getSpanningTree();
 // System.out.println("\nSpanning Tree Cost");
 //my.getSpanningTreeCost();
 }
}

Below MyGraph class does all the work of creating the graph by taking edges and calculating the spanning tree. I have used jgrapht library to create graph

import org.jgrapht.*;
import org.jgrapht.graph.*;
import org.jgrapht.alg.KruskalMinimumSpanningTree;
public class MyGraph {
 private UndirectedGraph<String, DefaultEdge> g = new SimpleGraph<String, DefaultEdge>(DefaultEdge.class);
 static final double DEFAULT_EDGE_WEIGHT=19;
 DefaultWeightedEdge>(DefaultWeightedEdge.class); 
 private DefaultWeightedEdge e1;
 public void addVertex(String name) {
 g.addVertex(name);
 //graph.addVertex(name);
 }
 public void addEdge(String v1,String v2) {
 g.addEdge(v1, v2);
 // e1=graph.addEdge(v1, v2);
 }
 /*public void setEdgeWeight() {
 graph.setEdgeWeight(e1, DEFAULT_EDGE_WEIGHT); 
 }*/
 public UndirectedGraph<String, DefaultEdge> getGraph() {
 return g;
 }
 /*public SimpleWeightedGraph<String,DefaultWeightedEdge> getGraph() {
 return graph;
 }*/
 public void getSpanningTree() {
 KruskalMinimumSpanningTree k=new KruskalMinimumSpanningTree(g);
 System.out.println(k.getEdgeSet().toString());
 //KruskalMinimumSpanningTree k1=new KruskalMinimumSpanningTree(graph);
 //System.out.println(k1.getEdgeSet().toString()); 
 }
 /*public void getSpanningTreeCost() {
 KruskalMinimumSpanningTree k=new KruskalMinimumSpanningTree(graph);
 System.out.println(k.getSpanningTreeCost());
 }*/ 
}

• seema: I tried using jGraphT library... I am getting edges and vertex details in logs, but nothing shows up on UI. Any idea what I am missing?