Persist Login State
Learn and practice how to store the login state in the Android key-value storage in this lesson.
We'll cover the following
Flow overview
When LoginActivity is opened, we need to check the login state:
- If the user is logged in already, we close LoginActivity and open MainActivity straightaway.
- If the user is not logged in, we proceed to the regular flow and save the login state in the end.
Shared preferences
In Android, we can use SharedPreferences
to store a simple key-value data… A key-value store is basically a Map
that is serialized to the disk as a file. This storage support saving the following types of data:
String
Boolean
Integer
Long
Float
Set<String> values
Any data stored in the SharedPreferences
is going to be persisted inside the internal application-specific file on the file system. Let’s learn how to create the SharedPreferences
and some basic operations.
To create new or load existing SharedPreferences
, we can use the Context#getSharedPreferences
method. Don’t forget that the Activity
class implements the Context
interface, so this method can be called inside the Activity
.
The getSharedPreferences
method has two required parameters:
- name - the shared preferences file name, in our case
travel-blog
- mode - the operating mode, in our case
Context.MODE_PRIVATE
means that only our application will have access to this shared preferences
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