Euler Circuit in an Undirected Graph

class Solution {
    int[] vis;
    public boolean isEularCircuitExist(int v, ArrayList<ArrayList<Integer>> adj) {
       //1...
       vis=new int[v+1];
       // Checking connected or not...
       dfs(0, vis, adj);
       
       for(int i=0;i<v;i++){
           if(vis[i]==0 && adj.get(i).size()>0)
           return false;
       }
       // 2...
       int cnt=0;
       for(int i=0;i<v;i++){
           if((adj.get(i).size()%2)==1)
           cnt++;
       }
       // Violates the condition for exactly once...
       if(cnt>2)
       return false;
       // Making, sure exactly once and diff start and end...
       else if(cnt==2)
       return false;
       // if(cnt==0)
       else
       return true;
    }
    void dfs(int u, int[] vis, ArrayList<ArrayList<Integer>> adj){
        vis[u]=1;
        for(int v:adj.get(u)){
            if(vis[v]==0)
            dfs(v, vis, adj);
        }
    }
}