Collect HashSet / Java 8 / Regex Pattern / Stream API

Question

Recently I change version of the JDK 8 instead 7 of my project and now I overwrite some code snippets using new features that came with Java 8.

final Matcher         


        

Answer 1

Here is the implementation using Spliterator interface.

    // To get the required set
   Set result = (StreamSupport.stream(new MatcherGroupIterator(pattern,input ),false))
           .map( s -> s.toLowerCase() )
           .collect(Collectors.toSet());
    ...
    private static class MatcherGroupIterator implements Spliterator {
      private final Matcher matcher;

      public MatcherGroupIterator(Pattern p, String s) {
        matcher = p.matcher(s);
      }

      @Override
      public boolean tryAdvance(Consumer action) {
        if (!matcher.find()){
            return false;
        }
        action.accept(matcher.group());
        return true;
      }

      @Override
      public Spliterator trySplit() {
        return null;
      }

      @Override
      public long estimateSize() {
        return Long.MAX_VALUE;
      }

      @Override
      public int characteristics() {
        return Spliterator.NONNULL;
      }
  }