Shared preferences

This is used to keep small data from session to session, for example the settings of an app or the scores of a game.

You define a "key" for the data.

final String  TEXTSIZESTRING="unique key for your value";

and then, in onCreate, you retrieve it using shared preferences.

SharedPreferences sp=getPreferences(MODE_PRIVATE);
Val.TextSize=sp.getFloat(Val.TEXTSIZESTRING,20);

In this case, the default value is 20.

Before exiting the app, you must write the new values for the data you want to keep.

SharedPreferences sp=getPreferences(MODE_PRIVATE);
SharedPreferences.Editor e=sp.edit();
e.putFloat(Val.TEXTSIZESTRING,Val.TextSize);
e.commit();