Sourcing Sample

Sample.java

class Sample {

  interface Source<T> {
    T get();
  }

  class WordsSource implements Source<List<Word>> {
    private final Document document;
    private final List<String> listOfWords;

    public WordsSource(Document document, List<String> listOfWords) {
      this.document = document;
      this.listOfWords = listOfWords;
    }

    public List<Word> get() {
     List<Word> words = document.getWords();

     return Lists.newArrayList(Iterables.filter(words, new Predicate<Word>() {
       public boolean apply(Word word) {         
        if (listOfWords.contains(word.getText())) {
          return true;
        }
        return false;
       }
     }
    }
  }  

}