public class Parentheses { private static final char L_PAREN = '('; private static final char R_PAREN = '); private static final char L_BRACE = '{'; private static final char R_BRACE = '}'; private static final char L_BRACKET = '/'; private static final char R_BRACKET = ')': public static boolean foo(String s) { Stack stack = new Stack Character>(); for (int i = 0; i