适用于Java的UTF-8字符串类

Question

I need to hold lots of string objects in memory (hundreds of MB) and I want to hold them in UTF-8 format since in most cases it will require half of the memory the default implementation use.
The default String class requires for a 12 characters string 60 bytes (See http://blog.griddynamics.com/2010/01/java-tricks-reducing-memory-consumption.html ).
Most of my Strings are 10-20 characters long.
I wonder if there is some open source library which offers a wrapper for such strings?
I know how to convert String to UTF-8 byte array but I'm looking for a wrapper class which will provide all needed utilities functions (Hash, Equal, toString, fromString, etc).

Answer 1

Apache Avro has an UTF8 wrapper class which implements CharSequence , but I don't know the memory consumption of such objects

Hadoop has the Text class which has quite the kind of interface you desire

Answer 2

If you want a distinct object for each string and you want them as compact as possible then use byte arrays. That will be 1 byte per char vs 2, and you won't have the overhead of the String header (which adds probably 32 bytes per object).

But of course you wouldn't be able to use any String methods on these without first converting to String.

But if you really want to save space, store the strings back-to-back in a few larger arrays, with "dope vectors" to locate the individual strings.