Android ArrayList of custom objects - Save to SharedPreferences - Serializable?

Question

I have an ArrayList of an object. The object contains the types 'Bitmap' and 'String' and then just getters and setters for both. First of all is Bitmap serializable?

How would I go about serializing this to store it in SharedPreferences? I have seen many people ask a similar question but none seem to give a good answer. I would prefer some code examples if at all possible.

If bitmap is not serializable then how do I go about storing this ArrayList?

Answer 1

Yes, you can save your composite object in shared preferences. Let's say..

 Student mStudentObject = new Student();
 SharedPreferences appSharedPrefs = PreferenceManager
             .getDefaultSharedPreferences(this.getApplicationContext());
 Editor prefsEditor = appSharedPrefs.edit();
 Gson gson = new Gson();
 String json = gson.toJson(mStudentObject);
 prefsEditor.putString("MyObject", json);
 prefsEditor.commit(); 

..and now you can retrieve your object as:

 SharedPreferences appSharedPrefs = PreferenceManager
             .getDefaultSharedPreferences(this.getApplicationContext());
 Gson gson = new Gson();
 String json = appSharedPrefs.getString("MyObject", "");
 Student mStudentObject = gson.fromJson(json, Student.class);

For more information, click here.

If you want to get back an ArrayList of any type object e.g. Student, then use:

Type type = new TypeToken<List<Student>>(){}.getType();
List<Student> students = gson.fromJson(json, type);