Mapping of strings to integers

Question

What is the easiest way in Java to map strings (Java String) to (positive) integers (Java int), so that

• equal strings map to equal integers, and
• different strings map to different integers?

So, similar to hashCode() but different strings are required to produce different integers. So, in a sense, it would be a hasCode() without the collision possibility.

An obvious solution would maintain a mapping table from strings to integers, and a counter to guarantee that new strings are assigned a new integer. I'm just wondering how is this problem usually solved. Would also be interesting to extend it to other objects than strings.

Answer 1

Have a look at perfect hashing.