CODEWITHSUNDEEP
javastringalgorithmlong-integer
Akka Jaworek
Akka Jaworek

Reputation: 2120

generate unique Long for unique String seed

I need to generate a unique Long of length of 10 or more digits from String seed that can be of any length. In normal circumstances it would be not possible to do since there are more String permutations than Long can store, however i know that system will not generate more Strings than i can store in Long, how can i generate unique Long for each String in such circumstances?

I can not use dynamic perfect hashing since is too time consuming and i can not use minimal perfect hash function since i dont want generated numbers to seqentional.

EDIT: i can not store any information about already processed Strings, including amount of them

Upvotes: 2

Views: 1377

Answers (1)

Peter Lawrey
Peter Lawrey

Reputation: 533492

You can use a counter like this

final AtomicLong counter = new AtomicLong();
final Map<String, Long> idMap = new LinkedHashMap<>();

public long idFor(String s) {
    return idMap.computeIfAbsent(s, isMap::incrementAndGet);
}

This will return a unique id for each String.

Upvotes: 6

Related Questions