ViewHolder class which caches views associated with the default Preference layouts. A ViewHolder describes an item view and metadata about its place within the RecyclerView. … Adapter implementations should subclass ViewHolder and add fields for caching potentially expensive View. findViewById(int) results.
What is ViewHolder pattern in Android?
The ViewHolder design pattern enables you to access each list item view without the need for the look up, saving valuable processor cycles. Specifically, it avoids frequent call of findViewById() during ListView scrolling, and that will make it smooth.
How does RecyclerView ViewHolder work?
As per Android documentation: RecyclerView is a UI component which allows us to create a scrolling list. It is basically a new ViewGroup used to render any adapter-based view in horizontal/vertical /grid or staggered grid manner using the Viewholder pattern.
What is a RecyclerView Android?
RecyclerView is the ViewGroup that contains the views corresponding to your data. It’s a view itself, so you add RecyclerView into your layout the way you would add any other UI element. … After the view holder is created, the RecyclerView binds it to its data. You define the view holder by extending RecyclerView.
How do you use getAdapterPosition?
Call getAdapterPosition() in your onClick() method because then at the time of the click you want to know the position of the item. If you check at the time of the creation it will (most of the times) be inaccurate.
How many times onCreateViewHolder called?
On reviewing LogCat I noticed that onCreateViewHolder was called twice after it was instantiated. Also onBindViewHolder was called twice though I know it is called whenever the items are recycled.
What is the difference between ListView and RecyclerView?
Simple answer: You should use RecyclerView in a situation where you want to show a lot of items, and the number of them is dynamic. ListView should only be used when the number of items is always the same and is limited to the screen size.
How does RecyclerView work?
RecyclerView can easily be called the better ListView. It works just like a ListView — displays a set of data on the screen but uses a different approach for the purpose. RecyclerView as its name suggests recycles Views once they get out of scope (screen) with the help of ViewHolder pattern.
How do I use RecyclerView?
Using a RecyclerView has the following key steps:
- Add RecyclerView AndroidX library to the Gradle build file.
- Define a model class to use as the data source.
- Add a RecyclerView to your activity to display the items.
- Create a custom row layout XML file to visualize the item.
- Create a RecyclerView.
What is onCreateViewHolder?
onCreateViewHolder() creates a new ViewHolder object whenever the RecyclerView needs a new one. This is the moment when the row layout is inflated, passed to the ViewHolder object and each child view can be found and stored.
What is difference between CardView and RecyclerView?
The new support library in Android L introduced two new UI widgets: RecyclerView and CardView. The RecyclerView is a more advanced and more flexible version of the ListView. … The CardView widget, on the other hand, is a new component that does not “upgrade” an existing component.
Should I use ListView or RecyclerView?
5 Answers. If ListView works for you, there is no reason to migrate. If you are writing a new UI, you might be better off with RecyclerView. RecyclerView is powerful when you need to customize your list or you want better animations.
What is Android ViewGroup?
A ViewGroup is a special view that can contain other views (called children.) The view group is the base class for layouts and views containers. This class also defines the ViewGroup. Android contains the following commonly used ViewGroup subclasses: LinearLayout.
What is onBindViewHolder position?
onBindViewHolder(VH holder, int position) Called by RecyclerView to display the data at the specified position. void. onBindViewHolder(VH holder, int position, List<Object> payloads) Called by RecyclerView to display the data at the specified position.