Matching Brackets

package StacksAndQueues;

import java.util.ArrayDeque;
import java.util.Scanner;

public class MatchingBrackets {
    public static void main(String[] args) {

        Scanner scanner = new Scanner(System.in);
        String expression = scanner.nextLine();
        ArrayDeque<Integer> stack = new ArrayDeque<>();

        for (int i = 0; i < expression.length(); i++) {
            char currentSymbol = expression.charAt(i);

            if (currentSymbol == '(') {
                stack.push(i);
            } else if (currentSymbol == ')') {
                int startSymbol = stack.pop();
                String contents = expression
                        .substring(startSymbol, i + 1);
                System.out.println(contents);
            }
        }
    }
}