Java code to create adjacency list for Graph DSA problems

AdjacencyList.java

import java.util.*;


public class Graph {
    
    private enum GraphType {
        DIRECTED,
        UNDIRECTED
    }
    
    // util method to add edge
    static void addEdge(List<List<Integer>> adjList, int from, int to, String graphType){
        adjList.get(from).add(to);
        if("UNDIRECTED".equalsIgnoreCase(graphType))
            adjList.get(to).add(from);
    }
    
    public static void main(String []args){
        int noOfEdges = 5;
        // initialization of adjacency list
        List<List<Integer>> adjList = new ArrayList<>(noOfEdges);
        for(int i = 0; i < noOfEdges; i++)
            adjList.add(new ArrayList<>());
        
        // now you can add edges
        addEdge(adjList, 1,2,"directed");
        addEdge(adjList, 1,3,"directed");
        addEdge(adjList, 2,4"directed");
        addEdge(adjList, 2,5,"directed");
        addEdge(adjList, 3,2,"directed");
        
        
    }