Exercise32_4.java

static int[][] computeLevenshtein(List<String> wordList, boolean parallel) {
    final int LIST_SIZE = wordList.size();
    int[][] distances = new int[LIST_SIZE][LIST_SIZE];

    Supplier<Stream<String>> streamSupplier = () -> wordList.stream();
    Stream<String> stream = streamSupplier.get();

    if (true == parallel) {
        stream = stream.parallel();
    }

    stream.map(a -> streamSupplier.get()
            .mapToInt(b -> Levenshtein.lev((String) a, (String) b)).toArray())
            .collect(Collectors.toList()).toArray(distances);

    return distances;
}

Exercise32_4_alt.java

static int[][] computeLevenshtein(List<String> wordList, boolean parallel) {
    final int LIST_SIZE = wordList.size();
    int[][] distances = new int[LIST_SIZE][LIST_SIZE];

    Stream<String> stream = wordList.stream();

    if (parallel) {
        stream = stream.parallel();
    }

    stream.map(a -> wordList.stream()
                            .mapToInt(b -> Levenshtein.lev(a, b))
                            .toArray())
          .collect(toList()).toArray(distances);

    return distances;
}