How to compress a String in Java?

Question

I use GZIPOutputStream or ZIPOutputStream to compress a String (my string.length() is less than 20), but the compressed result is long

Answer 1

Your friend is correct. Both gzip and ZIP are based on DEFLATE. This is a general purpose algorithm, and is not intended for encoding small strings.

If you need this, a possible solution is a custom encoding and decoding HashMap. This can allow you to do a simple one-to-one mapping:

HashMap toCompressed, toUncompressed;

String compressed = toCompressed.get(uncompressed);
// ...
String uncompressed = toUncompressed.get(compressed);

Clearly, this requires setup, and is only practical for a small number of strings.