multiple volley requests at same time

Question

I need to send 4 http requests at same time and wait until all of them finished (i'm using volley)

I've tried to send them separately in 4 threads and use thread.join but it seems that onResponse and onError methods are running in main thread so the request threads finishes after call queue.add(jsonArrayRequest).

I can't use countdownlatch because as I know first it doesn't run threads at same time (it runs them in a queue) and second it blocks main thread.

what's your suggestion? let me know if there's better way to do this using Retrofit , OkHttp or other libraries.

Answer 1

To achieve it without using any patterns or other libraries, you can mark the request as finished if it responded, and call the method, in each of them, you want to execute if all the requests are finished. On that method, you just need to check if all the requests are done.

Example:

isRequest1Finished = false;
isRequest2Finished = false;

response1 = null;
response2 = null;

volleyRequest1(new Response.Listener<Something>() {
  @Override
  public void onResponse(Something response) {
    isRequest1Finished = true;
    response1 = response;
    doSomething();
  } 
})

volleyRequest2(new Response.Listener<Something>() {
  @Override
  public void onResponse(Something response) {
    isRequest2Finished = true;
    response2 = response;
    doSomething();
  } 
})

//....do on all of your requests

and in your doSomething() method:

void doSomething() {
  if (isRequest1Finished && isRequest2Finished) {
    // do something with the response1, response2, etc....
  }
}

But my suggestion is using RxJava, where you can apply zip operator, in which it combines all of your asynchronous responses into one result:

Example:

Observable request1 = getRequest1();
Observable request2 = getRequest2();

Observable.zip(request1, request2,
  new BiFunction<Something, Something, Pair<Something, Something>() {
    @Override
    public Pair<Something, Something> apply(Something response1, Something response2) {
      return new Pair(response1, response2); // you can create a custom object to handle all of the responses
    }
  })
  .map( // do something with your responses )