I want to save Hashset Object in to Sharedpreference and than want retrieve that data. I am storing data in to hashset and and converting object in to json using Gson. Actually m storing bitmap in to Hashset. I am able to convert and save Hashsetobject  into  sharedpreference. I am getting problem when I am retrieving and converting json to Hashset Object.
HashSet<images> img = new HashSet<images>(CIRCLES_LIMIT);
Here is Method For Saving Object in to Sharedpreference.
  public void saveString() throws JSONException {
    Object spSquare = c.getStringDrawObjImages();
    SharedPreferences sharedPrefs = PreferenceManager.getDefaultSharedPreferences(getContext());
    SharedPreferences.Editor editor = sharedPrefs.edit();
    Gson gson = new Gson();
    String jsonSquare = gson.toJson(spSquare)
    editor.putString("kEySquare", jsonSquare);
    editor.commit();
}
Method For Retrieving That Object.
   public void openString() {
    SharedPreferences sharedPrefs = PreferenceManager.getDefaultSharedPreferences(getContext());
    Gson gson = new Gson();
    String jsonSquare=sharedPrefs.getString("kEySquare",null);
  Type typeSquare = new TypeToken<HashSet<images>>(){}.getType();
    HashSet<images> arrayListSquare = gson.fromJson(jsonSquare,typeSquare);`//getting Exception here jsonSyntax Error`
    if (arrayListSquare != null) {
        img = arrayListSquare;
    }
}