Kruskal's Algorithm using Priority Queue

    public class Main {
        public static void main(String[] args) {
            int noOfVertices = 5;

            List<int[]> adj=new ArrayList<>();
            //int[] = {source, destination, weight}
            adj.add(new int[]{0,1,4});
            adj.add(new int[]{0,2,1});
            adj.add(new int[]{1,2,2});
            adj.add(new int[]{1,4,5});
            adj.add(new int[]{2,3,4});
            adj.add(new int[]{3,4,3});

            PriorityQueue<int[]> q=new PriorityQueue<>((a,b) -> a[2]-b[2]);

            for(int[] edges:adj){
                q.add(edges);
            }

            List<int[]> mst =new ArrayList<>();

            while(!q.isEmpty() && mst.size()<noOfVertices-1){
                int[] edge=q.poll();

                int source=edge[0];
                int destination=edge[1];

                if(!isCycle(source,destination,mst,new boolean[mst.size()])){
                    mst.add(edge);
                }
            }

            System.out.println("MST formed by edges :");
            for(int[] edge:mst){
                    System.out.println((char)(edge[0]+'A')+" - "+(char)(edge[1]+'A')+" --> "+edge[2]);
            }
        }    

        static boolean isCycle(int source, int destination, List<int[]> mst, boolean[] visited){
            if(source==destination){
                return true;
            }
            boolean flag=false;
            for(int i=0;i<mst.size();i++){
                int[] edge=mst.get(i);
                if(!visited[i]){
                    if(source==edge[0]){
                        visited[i]=true;
                        flag=flag || isCycle(edge[1],destination,mst,visited);
                        visited[i]=false;
                    }
                    if(source==edge[1]){
                        visited[i]=true;
                        flag=flag || isCycle(edge[0],destination,mst,visited);
                        visited[i]=false;
                    }
                }
            }
            return flag;
        }
    }