Saving Data on Android

Wri/ng to preferences
Writing to the 
SharedPreferences
 is slightly more complicated. To write to the file 
you must open it for editing, by creating an 
Editor
. You can do that using 
edit()
 on 
your 
SharedPreferences
. The 
SharedPreferences.Editor
 is essentially a pointer to 
the 
SharedPreferences
 file, in the app's data directory. Then you pass key—value 
pairs to methods such as 
putInt()
, 
putString()
 and 
putLong()
. Once the key—
value pairs have been added to the 
Editor
, call either 
apply()
 or 
commit()
 to 
finalize the changes, and save to the file.
Generally, it is a good practice to choose 
apply()
 to write the 
SharedPreferences
. 
apply()
 will write the changes to the object out immediately, but then saves those 
changes to the disk asynchronously. If two 
Editor
s try to use 
apply()
 at the same 
time, the last one to call the function will be the one that has its changes saved. 
apply()
 will complete before the app switches states so you don't have to worry 
about it interfering with the lifecycle of your app. 
commit()
 writes the changes 
synchronously which can block the main thread and result in the app locking up, 
until everything is properly stored.
Now, it's time to look at an example of 
SharedPreferences
 in action.
GeTng started
To get started with prefs, locate this chapter's folder in the provided materials named