Creating a list of list after traversing binary search tree in level order

Here is my code.

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
public class Solution {
 public List<List<Integer>> levelOrder(TreeNode root) {
        List<List<Integer>> list = new LinkedList<List<Integer>>();
        if (root == null) {
            return list;
        } else {
            Queue<TreeNode> q = new LinkedList<>();
            q.add(root);
            while (!q.isEmpty()) {
                int size = q.size();
                LinkedList<Integer> layers = new LinkedList<>();
                while (size != 0) {
                    TreeNode current = q.poll();
                    layers.add(current.val);
                    if (current.left != null) {
                        q.add(current.left);
                    }
                    if (current.right != null) {
                        q.add(current.right);
                    }
                    size--;
                }

                list.add(layers);

            }
        }
        return list;

    }

}

Please let me know if any improvement/correction.