Android SharedPreferences

In this article we will discussing about how to use sharedpreferences in android. SharedPreferences is class for store data in session user you can retrieve key and value pair and we can  save your data with SharedPreferences.

Android SharedPreferences allow us to store private  primitive application data like boolean, long, double, int, String in the form key and value pair.

 I. Available of SharedPreferences Mode  

 1. MODE_WORLD_READABLE  = value  equal 1 .This constant was deprecated in API level 17.
Creating world-readable files is very dangerous, and likely to cause security holes in applications.

 2. MODE_WORLD_WRITEABLE = value equal 2 .This constant was deprecated in API level 17.
Creating world-writable files is very dangerous, and likely to cause security holes in applications.

 3. MODE_PRIVATE = value equal 0. File creation mode: the default mode, where the created file can only be accessed by the calling application.

 4. MODE_MULTI_PROCESS = value equal 4. This method will check for modification of preferences even if the sharedpreference instance has already been loaded

 5. MODE_APPEND = value equal 32768. This will append the new preferences with the already exisiting preferences
6. MODE_ENABLE_WRITE_AHEAD_LOGGING = value equal 8. Database open flag. When it is set , it would enable write ahead logging by default.

 II. How to get a handle to a SharedPreferences?

We can create a new shared preferences or access existing file one by using two methods

getSharedPreferences() — Use this if you need multiple shared preference files identified by name, which you specify with the first parameter. You can call this from any Context in your app.
getPreferences() — Use this from an Activity if you need to use only one shared preference file for the activity. Because this retrieves a default shared preference file that belongs to the activity, you don't need to supply a name.

Context context = getActivity();
SharedPreferences Pref = context.getSharedPreferences(
        getString(R.string.preference_file_key), Context.MODE_PRIVATE);

Store data to SharedPreferences

SharedPreferences pref = getActivity().getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();

    editor.putBoolean("key_name1", true);           // Saving boolean - true/false

    editor.putInt("key_name2", "int value");        // Saving integer

    editor.putFloat("key_name3", "float value");    // Saving float

    editor.putLong("key_name4", "long value");      // Saving long

    editor.putString("key_name5", "string value");  // Saving string



    // Save the changes in SharedPreferences

    editor.commit(); // commit change

Retrieving data from SharedPreferences 

    pref.getBoolean("key_name1", null);         // getting boolean

    pref.getInt("key_name2", null);             // getting Integer

    pref.getFloat("key_name3", null);           // getting Float

    pref.getLong("key_name4", null);            // getting Long

    pref.getString("key_name5", null);          // getting String

Delete Or Remove Data From SharedPreferences

    editor.remove("key_name3"); // will delete key key_name3

    editor.remove("key_name4"); // will delete key key_name4   

    // Save the changes in SharedPreferences

    editor.commit(); // commit changes

/************ Clear all data from SharedPreferences *****************/  

     editor.clear();

     editor.commit(); // commit changes

III. Start with SharedPreferences Simple Project

follow this article we will create new sharedpreferences from xml file and shared data to other activity, In this case I used xml file for create EditText for input data and showed on other activity (second activity).I used menu for show preferences dialog to insert data. 

1. Create new project File--> New --> Android Project rename your project as you want.

2. Open Project go to create menu for action with preferences menu /res/menu and follow with this code 

<menu xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    tools:context="com.example.sharedpreferencesandroid.SharedPreferencesMainActivity" >

    <item
        android:id="@+id/action_settings"
        android:orderInCategory="100"
        android:title="@string/action_settings"
        app:showAsAction="never"/>
    <item
        android:id="@+id/action_pref"
        android:title="@string/action_Pref"
        app:showAsAction="never"/>

</menu>

3. Create xml folder for store pref.xml under /res just right click New Folder and hit finish button

4. Create xml file call pref.xml in folder /xml for create preferences Right Click on folder New Android XML File and select resource type as Preferences  and type file name as you want and hit finish button. And follow with this code.

<?xml version="1.0" encoding="utf-8"?>
<PreferenceScreen xmlns:android="http://schemas.android.com/apk/res/android" >

    <EditTextPreference
        android:key="username"
        android:summary="please enter your name here!"
        android:title="Enter your Name:" >
    </EditTextPreference>
    <EditTextPreference
        android:key="userpass"
        android:summary="please enter your password"
        android:title="Enter Your Password:" />

</PreferenceScreen>