Is it advisable to store large strings in memory, or repeatedly read a file?

Question

Let's say I have various text/json/xml/whatever files (stored locally, in the assets directory), ranging in size from 20 - 500 KB. Assuming these files are going to be referenced frequently, throughout the application, is it better to:

A) Read the file once, the first time it's requested, and store the data in a variable

or

B) Read the file each time it's requested, grab the requested bit of information, and allow GC to clean up afterward?

Coming from web-dev, I generally use option (A), but I wonder if the storage limitation of mobile devices makes B preferred in this context (Android app development).

TYIA.

Answer 1

You can store your data into memory by compressing it.That it will reduce your memory footprint at any point of time.So this technique can be applicable to both PCs and mobile phones.Later on when you need the data, read and decompress it.So read the file once, then compress and store it in the memory.The following example uses GZIPOutputStream to compress a string.

public static String compress(String str){
    ByteArrayOutputStream out = new ByteArrayOutputStream();
    GZIPOutputStream gzip = new GZIPOutputStream(out);
    gzip.write(str.getBytes());
    gzip.close();
    return out.toString("ISO-8859-1");
 }

Answer 2

If the file is being requested frequently, definitely it's better to read the file once and store in cache.

You can also read this article titled How Google Taught me to Cache and Cash In in HighScalability website.

Answer 3

That depends on the total size of the files, accessing frequency, and your targeting customers. Although high-end phone got very large memory, the are many low-ends system which has fewer memory. It might deserve to use some LRU cache to reach a balance.