How can I update the list recyclerview using shared preferences in android?

Question

I am sending data from ItemDetails class to OrdersFragment using shared preferences. I receive the data successfully, but just the last item, it's overwritting item in the cart. How can I update the preferences I send from ItemDetails with new values?

This is my ItemDetails class:

btn_AddToCart.setOnClickListener(new View.OnClickListener() {
            @Override
            public void onClick(View v) {

                SharedPreferences sharedPreferences = getApplicationContext().getSharedPreferences(MY_PREFS_NAME, MODE_PRIVATE);
                Gson gson = new Gson();

                // send names
                ArrayList<String> namesList = new ArrayList<>();
                namesList.add(name);
                String namesJson = gson.toJson(namesList);
                sharedPreferences.edit().putString("names", namesJson).apply();

                // send prices
                ArrayList<String> pricesList = new ArrayList<>();
                pricesList.add(price);
                String pricesJson = gson.toJson(pricesList);
                sharedPreferences.edit().putString("prices", pricesJson).apply();

            }


        });

And this is OrdersFragment:

SharedPreferences sharedPreferences = context.getSharedPreferences(MY_PREFS_NAME, MODE_PRIVATE);
        Gson gson = new Gson();

        // get names
        ArrayList<String> namesList = new ArrayList<>();
        String namesJson = sharedPreferences.getString("names", null);
        String[] names = gson.fromJson(namesJson, String[].class);
        if (names != null) {
            namesList.clear();
            namesList.addAll(Arrays.asList(names));
        }

        // get prices
        ArrayList<String> pricesList = new ArrayList<>();
        String pricesJson = sharedPreferences.getString("prices", null);
        String[] prices = gson.fromJson(pricesJson, String[].class);
        if (prices != null) {
            pricesList.clear();
            pricesList.addAll(Arrays.asList(prices));
        }


        RecyclerView rvOrdered = view.findViewById(R.id.rv_ordered);
        rvOrdered.setLayoutManager(new LinearLayoutManager(context));
        rvOrdered.setHasFixedSize(true);

        //populate the orders list
        ArrayList<OrderedModel> orders = new ArrayList<>();

            for(int i = 0; i < namesList.size(); i++) {
                orders.add(new OrderedModel(namesList.get(i), pricesList.get(i)));
            }


        rvOrdered.setAdapter(new OrderedRecyclerViewAdapter(context, orders));

How can I update the list in ItemDetails and get all of the orders in OrdersFragment instead of one? Can I use multiple shared preferences or? I believe I have to fetch the data from fragment first and then just append the new values I guess?

Answer 1

First get the sharedPreferences using this:

SharedPreferences sharedPreferences = getApplicationContext().getSharedPreferences(MY_PREFS_NAME, MODE_PRIVATE);
String namesJson = sharedPreferences.getString("names", "");
String[] names = gson.fromJson(namesJson, String[].class);

Then make a new array and add all the old names plus the new name:

ArrayList<String> namesArray = new ArrayList<>();
for(String n : names) {
    namesArray.add(n);
}
namesArray.add(name); // add the new name here

Then save it again in ItemDetails before sending it over:

sharedPreferences.edit().putString("names", gson.toJson(namesArray)).apply();

Now you can access all the names, old and new, in OrdersFragment. Do the same for "prices", it works the same.