Log in\ Log out Session Management using shared Preferences in Android

                               Session are useful when you want to store user data globally through out the application. This can be done in two ways. One is storing them in a global variables and second is storing the data in shared preferences. The problem with storing data in global variable is data will be lost once user closes the application, but storing the data in shared preferences will be persistent even though user closes the application.


               Application shared preferences allows you to save and retrieve key, value pair data. Before getting into tutorial, I am giving basic information needed to work with shared preferences.

Initialization

Application shared preferences can be fetched using getSharedPreferences() method.You also need an editor to edit and save the changes in shared preferences. The following code can be used to get application shared preferences.

SharedPreferences pref = getApplicationContext().getSharedPreferences("MyPref", 0); // 0 - for private mode Editor editor = pref.edit();

Storing Data

You can save data into shared preferences using editor. All the primitive data types like booleans, floats, ints, longs, and strings are supported. Call editor.commit() in order to save changes to shared preferences.

editor.putBoolean("key_name", true); // Storing boolean - true/false editor.putString("key_name", "string value"); // Storing string editor.putInt("key_name", "int value"); // Storing integer editor.putFloat("key_name", "float value"); // Storing float editor.putLong("key_name", "long value"); // Storing long    editor.commit(); // commit changes

Retrieving Data

Data can be retrived from saved preferences by calling getString() (For string) method. Remember this method should be called on Shared Preferences not on Editor.

// returns stored preference value // If value is not present return second param value - In this case null pref.getString("key_name", null); // getting String pref.getInt("key_name", null); // getting Integer pref.getFloat("key_name", null); // getting Float pref.getLong("key_name", null); // getting Long pref.getBoolean("key_name", null); // getting boolean

Clearing / Deleting Data

If you want to delete from shared preferences you can call remove(“key_name”) to delete that particular value. If you want to delete all the data, call clear()

editor.remove("name"); // will delete key name editor.remove("email"); // will delete key email    editor.commit(); // commit changes

Following will clear all the data from shared preferences

editor.clear(); editor.commit(); // commit changes

The following is a simple tutorial which will have a login form and a dashboard screen. At first user will login using login details and once he successfully logged in his credentials (name, email) will be stored in shared preferences.

Download code from this Link: Session Management