Android Programming...

                  Handle to a SharedPreferences

You can create a new shared preference file or access an existing one by calling one of 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.

SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);

Caution: If you create a shared preferences file with MODE_WORLD_READABLE or MODE_WORLD_WRITEABLE, then any other apps that know the file identifier can access your data.

Write to Shared Preferences

---

To write to a shared preferences file, create a SharedPreferences.Editor by calling edit() on yourSharedPreferences.

Pass the keys and values you want to write with methods such as putInt() and putString(). Then callcommit() to save the changes. For example:

SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
SharedPreferences.Editor editor = sharedPref.edit();
editor.putInt(getString(R.string.saved_high_score), newHighScore);
editor.commit();

Read from Shared Preferences


To retrieve values from a shared preferences file, call methods such as getInt() and getString(), providing the key for the value you want, and optionally a default value to return if the key isn't present. For example:
SharedPreferences sharedPref = getActivity().getPreferences(Context.MODE_PRIVATE);
int defaultValue = getResources().getInteger(R.string.saved_high_score_default);
long highScore = sharedPref.getInt(getString(R.string.saved_high_score), defaultValue);



Available mode for shared preference:

   1. MODE_WORLD_READABLE
   2. MODE_WORLD_WRITEABLE
   3. MODE_PRIVATE





Store,Fetch,Remove,Clear Data from SharedPreferences.







/******* Create SharedPreferences *******/



    SharedPreferences pref = getApplicationContext().getSharedPreferences("MyPref", MODE_PRIVATE); 

    Editor editor = pref.edit();





/**************** Storing data as KEY/VALUE pair *******************/



    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 changes





/**************** Get SharedPreferences data *******************/



// If value for key not exist then return second param value - In this case null



    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









/************ Deleting Key value 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









we create shared preference fileto save currrent state of activity






for example:

onPause()

{

SharedPreferences.Editor editor = getSharedPreferences(file_name,MODE).edit();

                     or

SharedPreferences.Editor editor = getPreferences(MODE).edit(); // editing data stored in default preference file

//store data that we want to persist using edit.putString(TAG,VALUE),edit.putInt(TAG,VALUE)

}






Now , whenever activity is restarted restore the persistent state by specifying the preference file used for storing persistent data when activity is in its resume state



for example :



onResume()

{


SharedPreferences pref = getSharedPreferences(file_name,MODE);

                     or

SharedPreferences pref = getPreferences(MODE); // used for storing data in default preference file




//retrieve the state using pref.getString(TAG) or pref.getInt(TAG,DEFAULTVALUE)


}