[Android Bootcamp] Day 2 Instagram Photo Viewer - ready for review

[mishabosin]

Day 2 is code-complete, please review. /cc @codepathreview @codepath

[nickai]

:+1: Nice work Misha with the second day of the assignment! We've captured some of the best practices for today's assignment below. We recommend you take a look through these point-by-point to determine how you might be able to improve your submission. Can you also please update your GIF walkthrough each day with the completed stories?

• Did you create helper methods for Activity initialization in onCreate? This keeps lifecycle methods clean and increases readability, especially as your Activity increase in complexity.

• Loading adapter content. It's preferred that a convenience method be created on the adapter to reload content. This helps DRY up code and encapsulate adapter behavior if the Activity needs to call this several times in different places.

  public class CommentsAdapter extends RecyclerView.Adapter<CommentsAdapter.ViewHolder> {
  
   List<Comment> comments;
  
   public void refreshComments(List<Comment> newComments) {
       comments = newComments;
       notifyDataSetChanged();
    }
  }

• In RecyclerView.Adapter subclasses, context can be retrieved from either a view holder or the parent view. See this guide on Accessing context from RecyclerView.Adapter

• Attach any listeners in the ViewHolder to cut down on memory usage. Rather than setting OnClickListener instances in RecyclerView.Adapter.onBindViewHolder(), which causes more objects to be created, do the following:

  public class InstagramPostsAdapter extends RecyclerView.Adapter<InstagramPostsAdapter.ViewHolder> {
    @Override
    public void onBindViewHolder(ViewHolder holder, int i) {
        InstagramPost post = posts.get(i);
        holder.post = post;
    }
  
    public static class ViewHolder extends RecyclerView.ViewHolder {
        private InstagramPost post;
        private Button btnDoSomethingWithPost;
  
        public ViewHolder(View itemView) {
            super(itemView);
            btnDoSomethingWithPost = (Button) itemView.findViewById(R.id.btnDoSomethingWithPost);
            setupListeners();
        }
  
        void setupListeners() {
            btnDoSomethingWithPost.setOnClickListener(new View.OnClickListener(){
                @Override
                public void onClick(View v) {
                    // context can be referenced via v.getContext()
                    doSomethingWithPost(post);
                }
            });
        }
    }
  }

• Fetching data from the Instagram API to populate RecyclerViews
  • Did you setup your InstagramClient with an endpoint such as getPopularPosts? You should have a method that represents each endpoint and then accepts specific parameters and a “handler” as outlined here.
  • You should then make a call to getPopularPosts in your activity and the onSuccess should deserialize the response and then use it to populate a RecyclerView.Adapter.
• Handling Network Failures
  • When making network requests, it's important to handle error cases and take appropriate actions when the network request fails. For this reason, it is advisable to override the onFailure method in JsonHttpResponseHandler, and at a minimum, notifying the user via a Toast that the network request failed.