The goal of this chapter was to introduce developers to a non-perfect world where the old RxJava library meets the shiny RxJava 2.0.

We saw that it is very easy to make 1.0 version talk to the new 2.0 version with the help of the RxJava2Interop library.

There will be many libraries that won't migrate to a new version any time soon, so an ability to plug one into another will become an extremely useful item in your toolbox.

In particular, we will use one such library of great importance, that's called StorIO, to access the SQLite database, but we'll discuss more about that in the next chapter.

However, in general, it is better to avoid mixing two versions of RxJava as it includes additional dependencies that just makes your application heavier (RxJava 1.0 adds additional ~500kB) for no good reason--in the end, RxJava 1.0 and RxJava 2.0 basically do the same. Also, it can cause you to run into the DEX limit of method count.