Java tutorial
//package com.java2s; import android.content.SharedPreferences; public class Main { /** * @return {@code Boolean} value if {@code sharedPreferences} contains the value * corresponding to the {@code key}. Otherwise returns {@code null}. */ private static Boolean getBoolean(SharedPreferences sharedPreferences, String key) { if (!sharedPreferences.contains(key)) { return null; } // Default value wouldn't be used in actual case, but it is required. return Boolean.valueOf(sharedPreferences.getBoolean(key, false)); } }