Besides the types of Observable and Flowable, there are three more types that RxJava provides:

• Completable: This represents an action without a result that will be completed in the future
• Single: This is just like Observable (or Flowable) that returns a single item instead of a stream
• Maybe: This stands for an action that can complete (or fail) without returning any value (such as Completable) but can also return an item such as Single

However, all these are used quite rarely. Let's take a quick look at the examples.