![]() To keep things performant, we want a scrollbar that can accurately and smoothly track the user’s position in a list of content without knowing the entire list. The scrollbar will not move smoothly – it will jump around and resize. Unfortunately, a scrollbar that doesn’t behave erratically is not well supported out of the box when working with dynamically-sized items in a RecyclerView. It’s an important feature for a news publication to have, especially since articles have items varying in height, from one-line bylines to vertically-oriented images.Īs an Android developer on The Wall Street Journal, handling lists with content of varying heights is a common use case on Android. So, what we can do is that we can create a single ViewPool and pass it to all the inner RecyclerViews so that it gets shared like below: class OuterRecyclerViewAdapter() : RecyclerView.Scrolling in Android: Custom Scroll Behavior for a List of Varying HeightĪ scrollbar is a useful and recognizable way to show progress and position in a feed of content. The pool does not get shared between two RecyclerViews having the same types of views. OuterRecyclerViewīut by default, the optimization works for that particular RecyclerView because that particular RecyclerView has its own View Pool. If we have the use-case of Nested RecyclerView. ![]() tHasFixedSize(true) Use setRecycledViewPool for Optimizing Nested RecyclerViewĪs we know that the RecyclerView works on the principle of "Reuse View Using Pool" wherever possible.Ĭheck How does RecyclerView work internally? We should use this method if the height of all the items is equal. Nesting reduces RecyclerView performance. ![]() If possible, we should avoid a nested view and try to create a flat view wherever possible. It indicates whether each item in the data set can be represented with a unique identifier of type Long.Įven if we call the notifyDataSetChanged(), it does not have to handle the complete re-ordering of the whole adapter because it can find if the item at a position is the same as before and do less work. In case, we are forced to use notifyDataSetChanged() based on our use-case, we can try the setHasStableIds(true). adapter.notifyItemRemoved(position)Īdapter.notifyItemRangeInserted(start, end) Whenever we have the use-case of the removal, the updation, the addition of item, use the Notify Item API. We can see the improvement in our RecyclerView by doing so. We should check our onBindViewHolder method and optimize it. Our onBindViewHolder method should do very less work. Problem Solved! Do less in onBindViewHolder method Then, we will be able to set the width and height prior only. So, we should ask our backend developer to send the image size or the aspect ratio, accordingly, we can calculate the required width and height of the ImageView. If we do not set the correct image width and height prior, the UI will flicker during the transition of loading(downloading of image) and setting of the image into the ImageView(actually making it visible when downloading completes). If our image width and height are dynamic(not fixed), and we are getting the imageUrl from the server. If you are curious to know: How The Android Image Loading Library Glide and Fresco Works? Read here. So, always use Image-Loading libraries.ĭelegate all the image-related tasks to these libraries. The best part is that Image-Loading libraries like Glide, Fresco uses this bitmap pool concept. By using the bitmap pool concept, we can avoid it. Let's get started Use Image-Loading LibraryĪs the Garbage Collection(GC) runs on the main thread, one of the reasons for unresponsive UI is the continuous allocation and deallocation of memory, which leads to the very frequent GC run. Let's see what are the things which we can do to improve the performance of the RecyclerView and hence, we get the smooth scrolling. It leads to bad user experience as it seems that our Android App is laggy. When we implement RecyclerView in our Android Application, sometimes, we face problems like: The RecyclerView items are not scrolling smoothly. With these optimizations, we can make the RecyclerView scrolling smooth. In this blog, we are going to learn how to optimize the RecyclerView performance in Android.
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