CODEWITHSUNDEEP
javadesign-patternsrx-javareactive-programmingrx-java2
sdgfsdh
sdgfsdh

Reputation: 37121

How should I model processes in RxJava?

Suppose I have some process, such as downloading a file or running a big computation.

The events it fires might look like this: 

{ progress: "0%" }
{ progress: "23%" }
{ progress: "78%" }
{ progress: "100%" }
{ content: "Hello. world. " }

Or perhaps: 

{ progress: "0%" }
{ progress: "23%" }
{ error: "Access denied. " }

In each case, we have n status-updates (T) followed by either a result (S) or an error (Throwable): 

T* ( S | Throwable )

A process is a mix of Observable<T> and Single<S>.

There are a few ways to model a process using the Rx primitives:

How has this been successfully modelled in the past?

Which approaches are best and when should they be used?

Upvotes: 0

Views: 54

Answers (1)

Bob Dalgleish
Bob Dalgleish

Reputation: 8227

Let us rule out the Object plus instanceof right away. This is the certain road to madness.

It will depend on how you are going to use the T and S results. I believe that T should be a container of S.

class T<S> {
  public boolean isSuccess() { ... }
  public boolean isStatus() { ... }
  public Status getStatus() { ... }
  public S getResult() { ... }
}

The initial stream of emitted values have simply the status values (progress amounts), while the last item in the stream carries the S value.

If you need S to be a Single, then 

observable
  .filter( t -> t.isSuccess() )
  .last()
  .map( t -> t.getResult() )
  .toSingle()

will be adequate. If you need the status reports to appear elsewhere then use 

observable.filter( t-> t.isStatus() )

This gives you your

Upvotes: 1

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