how to use SharedPreferences outside of oncreate?

问题

How to use SharedPreferences in a class without oncreate ?

I get null pointer when accessing it.

  public class Ftr extends Activity 

   { 
    SharedPreferences preferences;

    Context ab=this;

  public void ft()
     {
       preferences = PreferenceManager.getDefaultSharedPreferences(ab);
      String result = preferences.getString("F","");
        }
      }

I'm calling Function ft() from another activity Ftr is just a class not an activity.

How can I use SharedPreferences in this condition?

回答1:

You can take in Common method or Utils So use in All Method.

  public static void SaveInPreference(Context mContext, String key, String objString) {
    SharedPreferences.Editor editor = mContext.getSharedPreferences(mContext.getString(R.string.app_name),
            Context.MODE_PRIVATE).edit();
    editor.putString(key, objString);
    editor.commit();
}

public static String getPrefString(Context mContext, final String key, final String defaultStr) {
    SharedPreferences pref = mContext.getSharedPreferences(mContext.getString(R.string.app_name),
            Context.MODE_PRIVATE);
    return pref.getString(key, defaultStr);
}

来源：https://stackoverflow.com/questions/19492710/how-to-use-sharedpreferences-outside-of-oncreate