Basics for views and how to create your own
What is a view? Why would I create my own? and…how does it work?
If you don’t know whether you need a custom view or not, you probably don’t. Most UI elements can be easily expressed using the elements of the Android framework, the support library, or the Google design library.
If you still did not find what you were looking for try GitHub first. Especially for Android there are thousands of libraries, some of them might do what you want. And now that you still didn’t find anything that you can or want to use, because your usecase is very special in some way…Now I have to admit: You probably need a custom view.