Question

How much space does a java string array take up?
More specifically, how much space (in bytes) does a string array that looks something like this:

Longbowman 
kingdom   
lord    
weapon1,weapon2,weapon3    
armor1,armor2,armor3

I ask this because I’m going to create a program that has 5,000+ of these arrays and want to know how much space it’ll take up so I’ll know if I should rework the data storage.

So to recap, how much space does a string array (if its quantifiable) take up?

Answer 1

The string array is just an array of references – an array of size N will take approximately (N * 4 + 20) or (N * 8 + 20) bytes depending on the size of a reference in your JVM.

If you’re interested in your total storage, you should work out how many separate String objects you’ve got, and also how many arrays you’ve got. If you’ve got 5000 arrays but they mostly contain references to the same few strings, it’s likely to be fine. If you’ve got 5000 arrays each of which contains 5 strings which aren’t used anywhere else, that’s 25,000 strings… which still probably isn’t very much (a string of length 20 will probably take about 60 bytes).

Of course, context matters here: what’s your code going to run on? If it’s running on a desktop PC, than taking a few megs probably isn’t a problem… it might be more of an issue on a phone.