HackerRank Java- Stack

A string containing only parentheses is balanced if the following is true: 1. if it is an empty string 2. if A and B are correct, AB is correct, 3. if A is correct, (A) and {A} and [A] are also correct.

Examples of some correctly balanced strings are: "{}()", "[{()}]", "({()})"

Examples of some unbalanced strings are: "{}(", "({)}", "[[", "}{" etc.

Given a string, determine if it is balanced or not.

import java.util.*;

class Solution {
    
    private static boolean isBalanced(String expression) {
        if ((expression.length() & 1) == 1)
            return false;

        char[] brackets = expression.toCharArray();
        Stack<Character> stack = new Stack<>();
        for (char bracket : brackets)
            switch (bracket) {
                case '{':
                    stack.push('}');
                    break;
                case '(':
                    stack.push(')');
                    break;
                case '[':
                    stack.push(']');
                    break;
                default:
                    if (stack.empty() || bracket != stack.peek())
                        return false;
                    stack.pop();
            }
        return stack.empty();
    }

    public static void main(String[] argh) {
        Scanner sc = new Scanner(System.in);

        while (sc.hasNext()) {
            String expression = sc.next();
            System.out.println(isBalanced(expression) ? "true" : "false");
        }
        sc.close();
    }
}