import java.io.File;
import java.util.ArrayList;
import java.util.List;


public class Node {

    String name;
    List<Node> children = new ArrayList<>();

    public Node(String name){
        this.name = name;
    }

    public void addChild(Node child){
        children.add(child);
    }

    public void afficher(String indent){
        System.out.println(indent + name);
        for(Node c : children){
            c.afficher(indent + "  "); // indentation augmentée
        }
    }

    public static Node build(File f){
        Node n = new Node(f.getName());
        File[] list = f.listFiles();

        if(list != null){
            for(File child : list){
                n.addChild(build(child)); // récursion OK
            }
        }

        return n;
    }

    public static void main(String[] args) {

        if(args.length != 1){
            System.out.println("Usage : java Node <repertoire>");
            return; // éviter un crash
        }

        File fichier = new File(args[0]);
        Node tree = build(fichier);
        tree.afficher("");
    }
}