Initialize_Map_Java8.java

import java.util.AbstractMap.SimpleEntry;
import java.util.*;
import java.util.stream.Collectors;
import java.util.stream.Stream;

class Balance {
  String hello = "hello";
  List<String> beginnings = Arrays.asList("[", "(", "{");
  Map<String, String> endingsToBeginnings = Collections.unmodifiableMap(Stream.of(
          new SimpleEntry<>("]", "["),
          new SimpleEntry<>(")", "("),
          new SimpleEntry<>("}", "{"))
          .collect(Collectors
                  .toMap(Map.Entry::getKey, Map.Entry::getValue)));


  ArrayDeque<String> stack = new ArrayDeque<>();



  public String notMatching = "()]".chars()
          .mapToObj(i -> Character.toString((char) i)).filter(letter -> {
            if (beginnings.contains(letter)) {
              stack.push(letter);
              return true;
            } else if (endingsToBeginnings.containsKey(letter)) {
              String expectedPunctuation = endingsToBeginnings.get(letter);
              String actualPunctuation = stack.peek();
              if (expectedPunctuation.equals(actualPunctuation)) {
                stack.pop();
                return true;
              }
            }
            return false;
          }
  ).findFirst().get();
}