I can't show any output and I've been having this error in calling DepthFirst Search in Main class

//THis is my main class
public class MainDriver{
  
    public static void main(String[] args) {
        
        Graph mygraph = new Graph(22);
        mygraph.addEdge(1,2);
        mygraph.addEdge(2,4);
        mygraph.addEdge(2,5);
        mygraph.addEdge(4,8);
        mygraph.addEdge(4,9);
        mygraph.addEdge(8,16);
        mygraph.addEdge(8,17);
        mygraph.addEdge(9,18);
        mygraph.addEdge(9,19);
        mygraph.addEdge(5,10);
        mygraph.addEdge(5,11);
        mygraph.addEdge(10,20);
        mygraph.addEdge(10,21);
        mygraph.addEdge(1,3);
        mygraph.addEdge(3,6);
        mygraph.addEdge(3,7);
        mygraph.addEdge(6,12);
        mygraph.addEdge(6,13);
        mygraph.addEdge(7,14);
        mygraph.addEdge(7,15);
        
    }
      
     DepthFirstSearch dfs = new DepthFirstSearch();
    
}

//This is my DFS class
public class DepthFirstSearch{

private boolean[] marked;
private int count;

public DepthFirstSearch(Graph G, int s) {
    marked = new boolean[G.getV()];
    dfs(G, s);

}

private void dfs(Graph G, int v) {
   
    marked[v] = true;
    System.out.print(v);
    count++;
    
    for (int w : G.adj(v)) {
        if (!marked[w]) {
            dfs(G, w);
        }
       
    }
    
}

public boolean marked(int w) {
    return marked[w];
    
}


public int count() {
    return count;
}

}