#RxBlrdroid

This is the codelab for the session on RxJava at Blrdroid (17th October, 2015).
The associated presentation can be found on my speakerdeck page.

##Overall objective Use the concepts of RxJava to orchestrate different operations in android. More specifically, we intend to make network calls to get lists of tracks created by 2 separate music bands and then using RxJava to combine and sort them. The results will be displayed in a RecyclerView.

##Concepts covered

• Creating Observables using Observable.create
• Using Retrofit to create Observables, here we create an Observable manually using a synchronous call in Retrofit
• Chaining operators to do transformations, combining and sorting collections
• Specifically covered operators like map and zip
• Using retrolambda
• Threading in RxJava
• Displaying results in a simple RecyclerView

##Steps to conduct the codelab

###Preparation This is the final output of the codelab, to get started, you would need to clone the repository and delete/clear some files/methods, more specifically

• Delete the Music.java class
• Clear the fabOnClick method inside MainActivity
• (Optional) In case you don't have Java 8 installed remove any references of Retrolambda from app/build.gradle, if you have please update the JDK link in build.gradle. In case you still face issues, checkout app/build.gradle from this commit.

Here are the actual steps in the codelab itself: ###Step 1: Understand how Observable.create and other operations like map work

• Create an Observable of type NetworkResponse from the synchronous call in Retrofit (the first call in MusicApi.java)
• Use the map operator to map from an Observable to Observable<List>
• Use the Thread Schedulers to do the network task and mapping in the background thread and the subscription in the main thread
• Once the fab is clicked on the screen, you would need display the results in provided RecyclerView

###Step 2: Showcase the use of the zip and map operators to orchestrate operations in android

• Create two separate Observable representing separate network calls for two separate search parameters
• Use the map operator to map from an Observable to Observable<List> for each of the results
• Then use the zip operator to combine for the Observable objects, in the zip function combine both the lists
• Use the map operator to sort the combined list of results
• Like before, use the Thread Schedulers to do the network task and mapping in the background thread and the subscription in the main thread
• Once the fab is clicked on the screen, you would need display the results in provided RecyclerView

##Dependencies

• AppCompat, RecyclerView and the Design support library
• Retrofit and GSON: for the network operations
• RxAndroid: for all Rx stuff
• Butterknife: for view injection
• (Optional) Retrolambda and Java 8: for the lambda operator