Data Storage in App

As I understand que -->
You want best way to store (serialize) object.
1. Using Internal file storage
pros :
1.You have more control over your data. PRIVATE_MODE gives security.
2.You don't have restriction in file dealing ie persisting / retrieving data.
3. uninstalling app , or doing clearing app data don't remove your data.
cons
1. You need to deal with internal storage memory available issue. Your app shouldn't consume much of users internal memory.

2. SQLLite
Pros: 1. SQL , deal with it using android sqlhelper class or use own SQL statements.Coding is easy. Best optimum file storage
2.Deal with memory ? No.
Cons :
1: when uninstalled app or user clicks on clear app data , removes all database
2. You need to follow DB structures.
3. Not much secured.

For shared preferences , you can only save content for primitive datatypes.
I am not sure if blob datatype is available in shared preferences for storing images.Even if it is available ,you will have to stream images by yourself.
If you are using this streaming method , Please be aware of "VM memory Budget exceeds the capacity" exception.
Do test your app with HD images so that you can encounter this exception.

It is easy for you to directly apply images from internet storage to Imageview using Bitmap and drawable classes. Just you need to deal with files.

You can also use DB SQLite but you have store images in DB using blob datatype and have to stream manually.

At last , Please be aware of "VM memory Budget exceeds the capacity" exception , if you use low size images for testing , you wont encounter this problem but in real world , people may use HQ images.
I hope that is helpful for you !

You are welcome !!