clait | Command Line Accounting & Invoicing Tool | Business library

On https://developer.android.com/reference/android/widget/ArrayAdapter, it says: You can use this adapter to provide views for an AdapterView, Returns a view for each object in a collection of data objects you provide, and can be used with list-based user interface widgets such as ListView or Spinner.

It also says: Note: If you are considering using array adapter with a ListView, consider using RecyclerView instead. RecyclerView offers similar features with better performance and more flexibility than ListView provides. See the Recycler View guide.

You are using RecyclerView.Adapter which is aimed to be used for RecyclerView. Therefore, we are not supposed to use ArrayAdapter with RecyclerView.

I think you can either use ArrayAdapter with ListView instead of RecyclerView or continue to use RecyclerView.Adapter with RecyclerView.

Also, your for loop (int i = 0; i < 1; i++) is redundant because this will loop only once (i = o and that's it). So you just create your 20 Course objects, then mCourses.addAll(Arrays.asList(course1, course2, course3));