rxjava to replace asynctask

gistfile1.kt

// Assume you have three class to represent state of operations,
// and they have a common base class

sealed class BaseClass {
    class ClassStart: BaseClass()
    class ClassProgress(var percent: Int): BaseClass()
    class ClassStop: BaseClass()
}

// Define the job here. It does not really execute it
fun jobObservable() = 
  Observable
  .just<BaseClass>(BaseClass.ClassStart())
  .observeOn(Schedulers.io())
  .concatMap { c ->
      Observable.create<BaseClass> { emitter ->
          (1..10).forEach {
              // do your background job here
              emitter.onNext(BaseClass.ClassProgress(it))
          }
      }
  }
  .observeOn(AndroidThread.mainThread())
  .concatMap<BaseClass> { Observable.just(BaseClass.ClassStop()) }
  .subscribeOn(AndroidSchedulers.mainThread())

// Actually do the job
fun doTheJob() {    
  val disposable = jobObservable().subscribe {
      when(it) {
          is BaseClass.Class1 -> System.out.println("Start")
          is BaseClass.Class2 -> System.out.println("Progress ${it.percent}")
          is BaseClass.Class3 -> System.out.println("Finish")
      }
  }
}