Question

I want to implement a high speed in memory implementation of Trie to create backend to auto suggestion / spell checker.
Is there already some good implementation based on in memory implementations like hazlecast.
Also which java open source tool is best suggested for these kind of usage

Answer 1

I would use a plain NavigableSet like TreeSet. Its built in and supports range searches.

 NavigableSet<String> words = new TreeSet<String>();
 // add words.
 String startsWith = ...
 SortedSet<String> matching = words.subSet(startsWith, startsWith + '\uFFFF');

If you want something more memory efficient you can use an array.

List<String> words = new ArrayList<String>();
words.add("aa");
words.add("ab");
words.add("ac");
words.add("ba");
Collections.sort(words);

String startsWith = "a";
int first = Collections.binarySearch(words, startsWith);
int last = Collections.binarySearch(words, startsWith.concat("\uFFFF"));
if (first < 0) first = ~first;
if (last < 0) last = ~last - 1;
for (int i = first; i <= last; i++) {
    System.out.println(words.get(i));
}