Kosaraju's Algorithm

public class Main {

    static boolean[] visited;
    static int[][] adjMatrix;
    static int noOfVertices;
    
    public static void main(String[] args) {

        noOfVertices=4;
        adjMatrix=new int[][]{
            {0,1,0,1},
            {0,0,1,0},
            {1,0,0,1},
            {0,0,0,0}
        };
        System.out.println("Each line is a list of vertex which form \na strongly connected component:");
        stronglyConnected();
    }
    
    static void stronglyConnected(){
        visited=new boolean[noOfVertices];
        Stack<Integer> stack=new Stack<>();
        
        //First DFS
        for(int vertex=0;vertex<noOfVertices;vertex++){
            if(!visited[vertex]){
                findOrder(vertex,stack);
            }
        }
        
        //Reverse All edges
        //Now edge is represented by 2 insted of 1
        transpose();     
        
        //Second DFS
        visited=new boolean[noOfVertices];
        
        //Printing all the strongly connected components
        while(!stack.isEmpty()){
            int vertex = stack.pop();
            if(!visited[vertex]){
                dfs(vertex);
                System.out.println("");
            }
        }
    }
    
    static void findOrder(int vertex,Stack<Integer> stack){
        visited[vertex]=true;
        
        for(int v=0;v<noOfVertices;v++){
            if(adjMatrix[vertex][v]==1 && !visited[v]){
                findOrder(v,stack);
            }
        }
        stack.push(vertex);
    }
    
    static void transpose(){
        for(int i=0;i<noOfVertices;i++){
            for(int j=0;j<noOfVertices;j++){
                if(adjMatrix[i][j]==1){
                    adjMatrix[i][j]=0;
                    adjMatrix[j][i]=2;
                }
            }
        }
    }
    
    static void dfs(int vertex){
        visited[vertex] = true;
        System.out.print(vertex+" ");
        
        for(int v=0;v<noOfVertices;v++){
            if(adjMatrix[vertex][v]==2 && !visited[v]){
                dfs(v);
            }
        }
    }
}