Reactive Programming with RxJava
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Reactive programming with RxJava allows for asynchronous and event-based programming by using Observables that push data via onNext(), onError(), and onComplete() calls, where Observables can be either "cold" and lazily produce values only after subscription or "hot" and produce values independently of subscriptions; key concepts include asynchronous data streams, the Observable interface and contract, and differences between RxJava 1 and 2 such as handling of null values and new types like Maybe and Processors.
Reactive Programming with RxJava
- 1. Reactive Programming with RxJava Reactive Extension for Java: why do we need it and how we can use it.
- 2. Roots and Motivation behind RxJava • What is reactive programming • Possible approaches to asynchronous programming model • Observable<T> - core concept, contract and interface • Push vs Pull and Iterable/Observable duality • Cold and Hot streams • Lazy evaluation • Diagrams • Operators
- 3. What is Reactive Programming? • Reactive programming is programming with asynchronous data streams Typical example:
- 4. • Why callbacks are inconvenient?
- 5. Observable • Push model • Contract – onNext(), onComplete(), onError(): • Zero or more onNext() • Exacly one onComplete() or onError()
- 6. Observable (continued) • Duality: Pull • T next() • Throw Exception • Returns Push • onNext(T) • onError(Throwable t) • onComplete()
- 7. Cold and Hot Streams • Cold streams: • Do not produce any event until subscription (Lazy) • Hot streams: • Production of events is out of control of application
- 8. Lazy VS Eager • RxJava adopts lazy model • Subscription, not construction starts work • Observables can be reused
- 9. RxJava 1 vs RxJava 2 • Handling of null values – RxJava 2 does not accept null values • Observable and Flowable – RxJava 2 has separated non- and backpressured versions • Maybe – RxJava 2 Observable for 0 or 1 element emission • Subjects and Processors – New RxJava 2 types for subject-like behavior (producer and consumer at the same time). Subjects are accompanying Observable while Processor – Flowable • Functional interfaces with Exception – RxJava 2 • Many smaller changes