Tree.java

import java.util.Arrays;
import java.util.LinkedList;
import java.util.List;

public class Tree
{

    public class Node
    {
        public List<Node> childList = new LinkedList<>();
        public List<Integer> numberList = new LinkedList<>();

        Node(LinkedList<String> l)
        {
            exitWhile:
            while (!l.isEmpty())
            {
                String s = l.pop();
                switch (s)
                {
                    case "[":
                        Node n = new Node(l);
                        childList.add(n);
                        break;
                    case "]": break exitWhile;
                    default : numberList.add(Integer.parseInt(s));break;
                }
            }
        }
        public int nodeSum()
        {
           int s = 0;
           for (Integer i: numberList){s += i;}
           System.out.println(s);
           return s;
        }
        public int sum()
        {
            int s = 0;
            if  (!childList.isEmpty()){for (Node x: childList){s += x.sum();}}
            s += nodeSum();
            return s;
        }
    }

    Tree (String[] treeStr)
    {
        LinkedList<String> l = new LinkedList<>(Arrays.asList(treeStr));
        Node n = new Node(l);
        System.out.println("Total sum:"+n.sum());

    }

    public static void main(String[] args)
    {
        String[] treeStr = {"[","1","[","2","3","]","4","[","5","[","6","7","]","]","[","8","]","]"};
        Tree t = new Tree(treeStr);
    }
}