observable
fun <T, R> observableUsing(resourceSupplier: () -> R, resourceCleanup: (resource: R) -> Unit, eager: Boolean = true, sourceSupplier: (resource: R) -> Observable<T>): Observable<T>
Returns an Observable that for each subscription acquires a new resource via resourceSupplier, then calls sourceSupplier and subscribes to the returned upstream Observable and disposes the resource via sourceSupplier when the upstream Observable is finished (either terminated or disposed).
Please refer to the corresponding RxJava document.