How to save complete recycler view data?

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Description

Suppose I have a RecyclerView that shows 50 photos from extras folder in internal storage. Considering that, That 50 photos are not going to change anytime. So, when user launches the app it fetches 50 photos from internet and saves in internal storage. if user launches photos activity then a cycle of fetching those 50 photos from extras folder will run. This cycle will fetch all the photos from the internal storage and will compare their BUCKET_DISPLAY_NAME with extras. If both are equal then and only it will be shown in recyclerView

considering this scenario, I want to save the recyclerView state or data in internal storage. So, when next time user opens app it will not go through fetching all the photos and instead it will direclty load recyclerview with photos which is saved.

Fetch Method

 public ArrayList<ImageModel> fetchImages() {
        uri = MediaStore.Images.Media.EXTERNAL_CONTENT_URI;
        projection = new String[]{MediaStore.Images.Media._ID, MediaStore.Images.Media.BUCKET_DISPLAY_NAME};
        cursor = activity.getApplicationContext().getContentResolver().query(uri, projection, null, null, null);
        column_index_data = cursor.getColumnIndexOrThrow(MediaStore.MediaColumns._ID);
        arrayList.clear();          
        while (cursor.moveToNext()) {
            long mediaId = cursor.getLong(column_index_data);
            name = cursor.getString(cursor.getColumnIndexOrThrow(MediaStore.Images.Media.BUCKET_DISPLAY_NAME));
            if (name.equals("extras")) {       
                Uri uriMedia = Uri.withAppendedPath(uri, "" + mediaId);
                ImageModel imageModel = new ImageModel();
                imageModel.setUri(uriMedia.toString());
                arrayList.add(imageModel);
            }
        }
        cursor.close();
        return arrayList;
    }

As you going through this method may take a lot of time if user has lot of photos other than required 50 photos.

then,

 arrayList = fetchImages();
adapter = new PhotosAdapter(requireActivity().getApplicationContext(), arrayList, getActivity(), this, this);
        recyclerView.setAdapter(adapter);

Using this method images are loaded in recyclerView.

So, is there any way to save the loaded RecyclerView or RecyclerView Data?

Doubt

According to, https://developer.android.com/reference/androidx/recyclerview/widget/RecyclerView.State

State object can also keep arbitrary data, identified by resource ids.

I don't understand much by arbitary data but, if it means recyclerView's data then How can I use RecyclerView.State object to restore the data inside recyclerView?

Note

Assume I can save any type of object in internal storage and load that object into another same class's object.

Edit As mentioned in answer loaded recyclerView cannot be stored. Instead data needs to be cached. As cache memory is inside the internal storage as well it is forcing my app to skip frames because I am loading images inside onCreateView() of my app. I can create a new Thread it will handle it in background and there are no skipped frames. But, It creates a blink effect which i don't want.

enter image description here no skipped frames

android-recyclerview android java
1 Answers

I don't understand much by arbitary data but, if it means recyclerView's data then How can I use RecyclerView.State object to restore the data inside recyclerView?

No, recyclerview's state refers to the recyclerview's state, like its vertical distance, view related data etc. The list/data factory is not handled by the recyclerview itself, rather it is provided by the Adapter. And there is no Adapter's state that is why you have to manage to load data into the adapter yourself.

As you going through this method may take a lot of time if user has lot of photos other than required 50 photos.

For your particular case, you can use cache directory for faster and easier access to your photos, you can just check if a photo exists in the cache, if not, then download, otherwise fetch it from cache. Official docs

I think that is all you want. However, if you further want to remember the last scroll position, you can do so by storing the last scroll position into SharedPreferences or similar utilities. Then after loading data, you can just manually scroll the recyclerview to that position.

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