RecyclerView is more flexible and advanced version of ListView and GridView. RecyclerView is used for providing a limited window to a large data set, which means it is used to display a large amount of data that can be scrolled very efficiently by maintaining a limited number of Views. In RecyclerView we supply data and define how each item looks, and the RecyclerView library dynamically creates the content when it is needed. RecyclerView was introduced in Material Design in Android 5.0(API level 21.0).
How RecyclerView Works?
- RecyclerView is a ViewGroup that contains Views corresponding to your data. It itself a View so, it is added to the layout file as any other UI element is added.
- ViewHolder Object is used to define each individual element in the list. View holder does not contain anything when it created, RecyclerView binds data to it. ViewHolder is defined by extending RecyclerView.ViewHolder.
- Adapters are used to bind data to the Views. RecyclerView request views, and binds the views to their data, by calling methods in the adapter. The adapter can be defined by extending RecyclerView.Adapter.
- LayoutManager arranges the individual elements in the list. It contains the reference of all views that are filled by the data of the entry.
LayoutManager class of RecyclerView provide three types of built-in LayoutManagers
- LinearLayoutManager: It is used for displaying Horizontal and Vertical List
- GridLayoutManager: It is used for displaying items in the forms of grids
- StaggeredGridLayoutManager: It is used for displaying items in form of staggered grids
In this example, we are going to use RecyclerView as ListView. Here, we are going to display the list of courses with their images as a vertical list using RecyclerView.
Step by Step Implementation
Step 1: Create A New Project
To create a new project in Android Studio please refer to How to Create/Start a New Project in Android Studio. Note that select Java as the programming language.
Step 2: Add Dependency
We are going to use RecyclerView as ListView. So, we need to add the dependency for it. For adding the dependency Go to Gradle Scripts > build.gradle(Module: app) and add the following dependency. After adding the dependency click on Sync Now.
Before moving further let’s add some color attributes in order to enhance the app bar. Go to app > res > values > colors.xml and add the following color attributes.
Step 3: Working with the activity_main.xml file
In this step, we will add a RecyclerView to our activity_main.xml file which is used to display data of listItems. Go to the app > res > layout > activity_main.xml and the following code snippet.
Step 4: Create a new layout file list_item.xml
In this step, we will create a new layout file for the single list item view. Go to app > res > layout > right-click > New > Layout Resource File and name it as list_item. list_item.xml contains an ImageView and a TextView which is used for populating the RecyclerView.
Step 5: Create a new Adapter class
Now, we will create an Adapter class that acts as a bridge between the UI Component and the Data Source .i.e., courseImg, courseName, and RecyclerView. Go to the app > java > package > right-click and create a new java class and name it as Adapter. Below is the code snippet is given for it.
Step 6: Working with the MainActivity file
In MainActivity.java class we create two ArrayList for storing courseImg and courseName. These images are placed in the drawable folder(app > res > drawable). You can use any images in place of these. And then we get the reference RecyclerView and set the LayoutManager as LinearLayoutManager and Adapter, to show items in RecyclerView. Below is the code for the MainActivity.java file.