Binary Tree -return all root to leaf paths

/**
 * Given a binary tree, return all root-to-leaf paths.

Note: A leaf is a node with no children.

Example:

Input:

   1
 /   \
2     3
 \
  5

Output: ["1->2->5", "1->3"]

Explanation: All root-to-leaf paths are: 1->2->5, 1->3Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    public List<String> binaryTreePaths(TreeNode root) {
        List<String> result = new ArrayList<String>();
        if(root == null){
            return result;
        }
        //String path = Integer.toString(root.val);
        traverse(result, Integer.toString(root.val), root);
        return result;
    }
    private void traverse(List<String> result, String path, TreeNode currNode){
        if(currNode.left == null && currNode.right == null){
          result.add(path);
          return;
        }
        if(currNode.left != null){
          traverse(result, path + "->"+ currNode.left.val, currNode.left);
        }if(currNode.right != null){
          traverse(result, path + "->"+ currNode.right.val, currNode.right);
        }
    }
}