Saving Data on Android

Internal Cache Files
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Internal cache files
Each app has a special and private cache directory to store temporary files. Android 
may delete these files when the device is low on internal storage space, so it’s not 
safe to store anything other than temporary files in this space. There’s also no 
guarantee that Android will delete these files for you, so you must maintain this 
directory yourself.
To write to the internal cache directory, use 
createTempFile
 as shown in the 
following example:
File.createTempFile(filename, 
null
, context.cacheDir)
A good use case for temporary files is when you’re uploading images to a server. You 
may not need the image persisted on the device, but you still need to upload 
some
 
file. In this case, a temporary file works well. You’d store the image in this temp file, 
upload it, and then delete the file upon completion.
Now that you have utilized the important features of internal storage, it’s time to 
look at how to store files on