How to use RxJava for asynchronous programming in Java

RxJava is a Java library for implementing asynchronous programming. It is based on the Observer pattern and the Iterator pattern, and provides a rich set of operators to handle the asynchronous event flow. RxJava uses the Observer pattern to process data flows, which includes two main roles: Observable and Observer. Observable generates a series of events (which can be data, errors, or completion signals), and the Observer subscribes to Observable and responds to the generated events. To facilitate processing and converting event streams, RxJava also provides a large number of operators. These operators can be used for filtering, transforming, merging, combining, and delaying, among others. By using these operators, we can handle asynchronous event flows in a declarative manner. The following is an introduction and sample code of some commonly used RxJava methods: 1. Create Observable: Observable<String> observable = Observable.just("Hello", "RxJava"); observable.subscribe(new Observer<String>() { @Override public void onSubscribe(Disposable d) { //Processing logic during subscription } @Override public void onNext(String s) { //Processing logic when receiving data } @Override public void onError(Throwable e) { //Processing logic when an error occurs } @Override public void onComplete() { //Processing logic at completion } }); 2. Filter operator: Observable<Integer> observable = Observable.just(1, 2, 3, 4, 5); Observable. filter (number ->number% 2==0)//Filter out even numbers . subscribe (number ->System. out. println (number))// The output result is: 2, 4 3. Conversion operator (map): Observable<Integer> observable = Observable.just(1, 2, 3, 4, 5); Observable. map (number ->number * 2)//Multiply each number by 2 . subscribe (number ->System. out. println (number))// The output results are: 2, 4, 6, 8, 10 4. Merge operator: Observable<Integer> observable1 = Observable.just(1, 2, 3); Observable<Integer> observable2 = Observable.just(4, 5, 6); Observable<Integer>mergedObservable=Observable. merge (observable1, observable2)// Merge two Observable MergedObservable. subscribe (number ->System. out. println (number))// The output results are: 1, 2, 3, 4, 5, 6 5. Delay operator: Observable<Integer> observable = Observable.just(1, 2, 3); Observable. delay (1, TimeUnit. SECONDS)//Delay transmitting data by 1 second . subscribe (number ->System. out. println (number))// The output results are: 1, 2, 3 (emitting after a delay of 1 second) The Maven dependency of RxJava is: <dependency> <groupId>io.reactivex.rxjava2</groupId> <artifactId>rxjava</artifactId> <version>2.2.19</version> </dependency>