Java balanced expressions check {[()]}

Question

I am trying to create a program that takes a string as an argument into its constructor. I need a method that checks whether the string is a balanced parenthesized expressio

Answer 1

package Stack;

import java.util.Stack;

public class BalancingParenthesis {

 boolean isBalanced(String s) {

    Stack stack = new Stack();

    for (int i = 0; i < s.length(); i++) {

        if (s.charAt(i) == '(' || s.charAt(i) == '{' || s.charAt(i) == '[') {

            stack.push(s.charAt(i)); // push to the stack

        }

        if (s.charAt(i) == ')' || s.charAt(i) == '}' || s.charAt(i) == ']') {

            if (stack.isEmpty()) {
                return false; // return false as there is nothing to match
            }

            Character top = stack.pop(); // to get the top element in the stack

            if (top == '(' && s.charAt(i) != ')' || top == '{' && s.charAt(i) != '}'
                    || top == '[' && s.charAt(i) != ']') {

                return false;
            }

        }

    }

    if (stack.isEmpty()) {
        return true; // check if every symbol is matched
    }

    return false; // if some symbols were unmatched
}

public static void main(String[] args) {

    BalancingParenthesis obj = new BalancingParenthesis();

    System.out.println(obj.isBalanced("()[]{}[][]"));

}

}

// Time Complexity : O(n)