Maximum XOR of two numbers in an array

class Solution {
    public int maxXor(int[] arr) {
        TrieNode root = new TrieNode();
        int maxResult = 0;

        for (int num : arr)
            insert(root, num);

        for (int num : arr)
            maxResult = Math.max(maxResult, findMaxXor(root, num));

        return maxResult;
    }

    private void insert(TrieNode root, int num) {
        TrieNode node = root;
        for (int i = 31; i >= 0; i--) {
            int bit = (num >> i) & 1;
            if (node.children[bit] == null)
                node.children[bit] = new TrieNode();

            node = node.children[bit];
        }
    }

    private int findMaxXor(TrieNode root, int num) {
        TrieNode node = root;
        int maxXor = 0;
        for (int i = 31; i >= 0; i--) {
            int bit = (num >> i) & 1;
            int oppositeBit = bit ^ 1;
            if (node.children[oppositeBit] != null) {
                maxXor |= (1 << i);
                node = node.children[oppositeBit];
            } else
                node = node.children[bit];

        }
        return maxXor;
    }
}

class TrieNode {
    TrieNode[] children = new TrieNode[2];
}