Store images url in sharedpreferences and display them in Recyclerview

Question

i'm trying to add (add to favorite) feature to my app,for that i used sharedpreferences my code below works but when i dispay images i see only the last image i added and i belive instead of add new image to favorite section i repaced by the old one :

here's my code for add and remove url from arraylist

  public void add(String name, String url) {
        ArrayList<Post> myfav = new ArrayList<>();
        Post post = new Post();
        post.setImgUrl(url);
        post.setName(name);
        myfav.add(post);
        TinyDB tinydb = new TinyDB(getApplicationContext());
        tinydb.putListObject("fav", myfav);
        Toast.makeText(getApplicationContext(), "added to fav", Toast.LENGTH_SHORT).show();
    }

    public void remove(String url) {
    TinyDB tinydb = new TinyDB(getApplicationContext());
    ArrayList<Post> myfavSaved;
    myfavSaved = tinydb.getListObject("fav", Post.class);
    for (int i = 0; i < myfavSaved.size(); i++) {
        if (myfavSaved.get(i).getImgUrl().equalsIgnoreCase(url)) {
            myfavSaved.remove(i);
            saveFav(myfavSaved);
        }
    }
    Toast.makeText(getApplicationContext(), "removed from fav", Toast.LENGTH_SHORT).show();
}

public void saveFav(ArrayList<Post> arrayList) {
    TinyDB tinydb = new TinyDB(getApplicationContext());
    tinydb.putListObject("fav", arrayList);
}

Favorite Fragment : which i display the images in RecyclerView

    public View onCreateView(final LayoutInflater inflater, final ViewGroup container, Bundle savedInstanceState) {
        View v = inflater.inflate(R.layout.fragment_fav, container, false);
        posts = new ArrayList<>();
        recyclerView = v.findViewById(R.id.rc);
        layoutManager = new GridLayoutManager(getActivity(), 2);
        recyclerView.setLayoutManager(layoutManager);
        recyclerView.setHasFixedSize(true);
        fetchRemoteData();
        return v;
    }

    public void onSuccess(List<Post> posts) {
        if (adapter == null) {
            adapter = new MyAdapter(posts, getActivity(), new RecyclerViewClickListener() {
                @Override
                public void onClick(View view, Post post) {
                    Intent intent = new Intent(getActivity(), Pop.class);
                    intent.putExtra("img", post.getImgUrl());
                    intent.putExtra("cat", "fav");
                    if (post.getName().isEmpty()) {
                        intent.putExtra("name", "Unknown");
                    } else {
                        intent.putExtra("name", post.getName());
                    }
                    startActivity(intent);
                    getActivity().overridePendingTransition(R.anim.fadein, R.anim.fadeout);
                }
            });
            recyclerView.setAdapter(adapter);
        } else {
            adapter.getItems().clear();
            adapter.getItems().addAll(posts);
            adapter.notifyDataSetChanged();
        }
    }

    private void fetchRemoteData() {
        TinyDB tinydb = new TinyDB(getActivity());
        ArrayList<Post> myfavSaved;
        List<Post> listItems = new ArrayList<>();
        myfavSaved = tinydb.getListObject("fav", Post.class);
        for (int i = 0; i < myfavSaved.size(); i++) {
            Post item = new Post(myfavSaved.get(i).getImgUrl(), myfavSaved.get(i).getName());
            listItems.add(item);
        }
        onSuccess(listItems);
    }
}

Answer 1

You are always adding a new list of object in your add() (first line). Instead you have to retrieve the listobject first and then add your new favorite post.

Try this :

 public void add(String name, String url) {
    //code to retrieve your arraylist stored in SharedPrefs
    TinyDB tinydb = new TinyDB(getApplicationContext());
    ArrayList<Object> postObjects = tinydb.getListObject("fav", Post.class);
    ArrayList<Post> myfav = new ArrayList<Post>();
    for(Object objs : postObjects){
        myfav.add((Post)objs);
    }
        Post post = new Post();
        post.setImgUrl(url);
        post.setName(name);
        myfav.add(post);
        tinydb.putListObject("fav", myfav);
        Toast.makeText(getApplicationContext(), "added to fav", Toast.LENGTH_SHORT).show();
 }