Maximum size to store in a String (the base64 of a file) - Java

Question

I have a file, then I convert it to base64 and finaly this base64 is stored into a String variable.

And the question is, what is the maximum size of the file that I can convert to base64 and store it in a String variable?

If anyone could help me. Thank you in advance

(With Java of course...)

See also [How many characters can a Java String have?](https://stackoverflow.com/questions/1179983/how-many-characters-can-a-java-string-have) — Andy Thomas, May 26 '17 at 16:28

score 2 · Accepted Answer · answered May 26 '17 at 16:27

2

Strings can hold a lot of data* - I'd be more concerned about your available heap memory if you're putting a whole file into memory that way. Especially as you have to be careful not to have it in memory twice for the base64 conversion...

*String is internally backed by an array and can hold up tp Integer.MAX_VALUE characters (2^31-1)

If you do have enough heap memory for your process you can calculate like this:

A char value in Java takes up 2 bytes of memory
Every character of your base64 encoded file takes of two bytes internally
base64 encoding makes 4 characters out of 3 bytes.

Apply some math and see if it fits or think hard and long why you need that data in memory in the first place.

answered May 26 '17 at 16:27

Jan

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yes, but whats is **approximately** the maximum size of the file that I can use... – LetsGoBrandon May 26 '17 at 16:34
That depends approximately on your memory... how much heap is assigned? How much will you need during copy? – Jan May 26 '17 at 16:35
my max heap size is 4'294'967'296 and my initial heap size is 268'435'456 – LetsGoBrandon May 26 '17 at 16:40
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So max heap = 2x maxint bytes = maxint chars in string = 3/4 maxint bytes in base64 = somewhere around 1,5 gb file. – Jan May 26 '17 at 16:56

Maximum size to store in a String (the base64 of a file) - Java

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