quick poc of matching balanced brackets, braces,...

StringMatcherApp.java

import java.util.List;
import java.util.Stack;
import java.util.stream.Collectors;
import java.util.stream.Stream;

public class StringMatcherApp {

    public static void main(String[] args) {
        String[] source = {"{}[]()", "{]}]"};
        System.out.println("source ...");
        Stream.of(source)
                .forEach((v) -> {
                    System.out.println(v);
                });

        String[] sink = StringMatcherApp.braces(source);

        System.out.println("sink: ...");
        Stream.of(sink)
                .forEach((v) -> {
                    System.out.println(v);
                });

    }

    public static String[] braces(String[] values) {
        List<String> l = Stream.of(values)
                .map(v -> {
                    if (check(v)) {
                        return "YES";
                    } else {
                        return "NO";
                    }
                }).collect(Collectors.toList());

        return l.stream().toArray(String[]::new);
    }

    public static boolean check(String s) {
        Stack<Character> stack = new Stack<Character>();
        for (int i = 0; i < s.length(); i++) {
            char c = s.charAt(i);
            if (c == '[' || c == '(' || c == '{') {
                stack.push(c);
            } else if (c == ']') {
                if (stack.isEmpty()) return false;
                if (stack.pop() != '[') return false;
            } else if (c == ')') {
                if (stack.isEmpty()) return false;
                if (stack.pop() != '(') return false;
            } else if (c == '}') {
                if (stack.isEmpty()) return false;
                if (stack.pop() != '{') return false;
            }
        }
        return stack.isEmpty();
    }
}