Simple File System in Java

 Key for File System is to use Node and Tree to represent file system. And use DFS to insert/validate node.

import java.util.HashMap;
import java.util.Map;

public class Test {
    public static void main(String[] args){
        String[] files = {
                "/app/assets/html/a.html",
                "/app/assets/html/b.html",
                "/app/assets/js/c.js",
                "/app/assets/js/d.js",
                "/app/index.html"
        };

        Tree tree = new Tree();
        for (String file:files){
            tree.insertFile(file);
        }
        System.out.println(tree.checkIfExist("/app/assets/js/c.js"));
        System.out.println(tree.checkIfExist("/app/assets/js/d.js"));
        tree.printFiles();
    }
}
class Node{
    String name;
    Map<String, Node> children;

    Node(String name){
        this.name=name;
        children = new HashMap<>();
    }
}
class Tree{
    Node root;
    Tree(){
        this.root = new Node("");
    }

    void insertFile(String filePath){
        String[] folders = filePath.split("/");
        Node cur = root;
        for(String folder:folders){
            if(!cur.children.containsKey(folder)){
                cur.children.put(folder, new Node(folder));
            }
            cur = cur.children.get(folder);
        }
    }

    boolean checkIfExist(String file){
        String[] folders = file.split("/");
        Node cur=root;
        for(String folder:folders){
            if(!cur.children.containsKey(folder)){
                return false;
            }else{
                cur=cur.children.get(folder);
            }
        }
        return true;
    }

    void printFiles(){
        dfsPrint(root,"");
    }

    void dfsPrint(Node node, String indent) {
        if(node.children.isEmpty()){
            System.out.println(indent + "-- " + node.name);
            return;
        }
        System.out.println(indent + "-- "+node.name);
        for(Node child:node.children.values()){
            dfsPrint(child, indent + "  ");
        }
    }
}