What is the correct way to share data between different Activities or Fragments?

Question

I need an app that should have a UI workflow where in a user should be able to browse a particular section of the app which can be either a ListView or a GridView and where

Answer 1

Android provides mapping from String values to various Parcelable types using Bundle.

For activity:-

Intent in = new Intent(Sender.this, Receiver.class); 
in.putString(key, value)
startActivity(in);

For Fragment use Bundle:-

Fragment fragment = new Fragment(); 
Bundle bundle = new Bundle();
bundle.putInt(key, value);
fragment.setArguments(bundle);

Edit for your scenario : I think the better option is create ApplicationPool.

Follow the below steps:- Initiate the ApplicationPool :-

ApplicationPool pool = ApplicationPool.getInstance();

modify the data on details page and add to pool

pool.put("key", object);

get the modified data on list page from pool

Object  object = (Object) pool.get("key");

important notes:- notify the listview or gridview after getting the data

ApplicationPool class file

public class ApplicationPool {

    private static ApplicationPool instance;
    private HashMap<String, Object> pool;

    private ApplicationPool() {
        pool = new HashMap<String, Object>();
    }

    public static ApplicationPool getInstance() {

        if (instance == null) {
            instance = new ApplicationPool();

        }

        return instance;
    }

    public void clearCollectionPool() {
        pool.clear();
    }

    public void put(String key, Object value) {
        pool.put(key, value);
    }

    public Object get(String key) {
        return pool.get(key);
    }

    public void removeObject(String key) {

        if ((pool.get(key)) != null)
            pool.remove(key);

    }
}