Search results for: Open API

by 0 comments on "Read and write Excel files in Java"

<dependency> <groupid>org.apache.poi</groupid> <artifactid>poi-ooxml</artifactid> <version>5.0.0</version> </dependency> If you are not familiar with Maven, you can check out this tutorial: Create Java Project with Maven. import lombok.AllArgsConstructor; import lombok.Builder; import lombok.Data; import lombok.NoArgsConstructor; @Data @AllArgsConstructor @NoArgsConstructor public class Product { private int id; private String color; private String size; private int cost; private String description; } import org.apache.poi.ss.usermodel.Cell;…

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by 0 comments on "Testing with StepVerifier in Project Reactor"

<dependency> <groupid>io.projectreactor</groupid> <artifactid>reactor-test</artifactid> <version>3.1.0.RELEASE</version> <scope>test</scope> </dependency> class ReactiveJavaTutorialTest { @Test public void testFlux() { //Create a Flux Flux <Integer> fluxToTest = Flux.just(1, 2, 3, 4, 5); // Create a test StepVerifier.create(fluxToTest) .expectNext(1) .expectNext(2) .expectNext(3) .expectNext(4) .expectNext(5) .expectComplete() // we expect Flux to complete after sending the number 5 which is the last element .verify(); }…

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by 0 comments on "Implementing Backpressure in Project Reactor"

class ReactiveJavaTutorial { public static void main(String[] args) { Flux<String> cities = Flux.fromIterable( new ArrayList<>(Arrays.asList(“New York”, “London”, “Paris”, “Toronto”, “Rome”))); cities.log().subscribe(); } } Output: INFO 6832 — [ main] reactor.Flux.Iterable.1 : | onSubscribe([Synchronous Fuseable] FluxIterable.IterableSubscription) INFO 6832 — [ main] reactor.Flux.Iterable.1 : | request(unbounded) INFO 6832 — [ main] reactor.Flux.Iterable.1 : | onNext(New York) INFO…

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by 0 comments on "subscribeOn and publishOn operators in Project Reactor"

class ReactiveJavaTutorial { public static void main(String[] args) { Flux<String> cities = Flux.just(“New York”, “London”, “Paris”, “Amsterdam”) .map(String::toUpperCase) .filter(cityName -> cityName.length() <= 8) .map(cityName -> cityName.concat(” City”)) .log(); cities.subscribe(); } Output: INFO 14040 — [main] reactor.Flux.MapFuseable.1 : | onSubscribe([Fuseable] FluxMapFuseable.MapFuseableSubscriber) INFO 14040 — [main] reactor.Flux.MapFuseable.1 : | request(unbounded) INFO 14040 — [main] reactor.Flux.MapFuseable.1 : |…

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by 0 comments on "Reactor Execution Model – Threading and Schedulers"

class ReactiveJavaTutorial { public static void main(String[] args) { Flux<String> cities = Flux.just(“New York”, “London”, “Paris”, “Amsterdam”) .map(String::toUpperCase) .filter(cityName -> cityName.length() <= 8) .map(cityName -> cityName.concat(” City”)) .log(); cities.subscribe(); } } INFO 14040 — [main] reactor.Flux.MapFuseable.1 : | onSubscribe([Fuseable] FluxMapFuseable.MapFuseableSubscriber) INFO 14040 — [main] reactor.Flux.MapFuseable.1 : | request(unbounded) INFO 14040 — [main] reactor.Flux.MapFuseable.1 : |…

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by 0 comments on "A Guide to use Keycloak with Spring Boot"

This tutorial will teach you how to use Keycloak to secure your Spring Boot Application. To find other tutorials, check the Keycloak tutorials page. What is Keycloak? According to Keycloak’s  official website, It is an open-source Identity and Access Management solution aimed at modern applications and services. It makes it easy to secure applications and…

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by 0 comments on "Create AWS Lambda Functions from Spring Cloud Functions"

This tutorial is about creating Lambda functions from Spring Cloud Functions. Spring Cloud Functions provide a way to implement the business logic via functions and decouple code development from the runtime target. Hence, the developer can focus solely on the implementation of logic. The developer need not worry about the target endpoint type, connectivity, integration,…

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by 0 comments on "Hot and Cold Publishers in Project Reactor"

class ReactiveJavaTutorial { public static void main(String[] args) throws InterruptedException { Flux<String> netFlux = Flux.fromStream(ReactiveJavaTutorial::getVideo) .delayElements(Duration.ofSeconds(2)); // each part will play for 2 seconds // First Subscriber netFlux.subscribe(part -> System.out.println(“Subscriber 1: ” + part)); // wait 5 seconds before next Subscriber joins Thread.sleep(5000); // Seconds Subscriber netFlux.subscribe(part -> System.out.println(“Subscriber 2: ” + part)); Thread.sleep(60000); }…

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by 0 comments on "RetryFailed Operation in Project Reactor"

class ReactiveJavaTutorial { public static void main(String[] args) { Mono.just(“data1”) .concatWith(Flux.error(new RuntimeException(“Exception occurred.”))) .doOnError(ex -> System.out.println(“LOG: Exception caught: ” + ex)) .retry(3) //retry 3 times in case of an error .log() .subscribe(); } } Output: reactor.Flux.Retry.1 : onSubscribe(FluxRetry.RetrySubscriber) reactor.Flux.Retry.1 : request(unbounded) reactor.Flux.Retry.1 : onNext(data1) LOG: Exception caught: java.lang.RuntimeException: Exception occurred. reactor.Flux.Retry.1 : onNext(data1) LOG: Exception…

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by 0 comments on "Handling Exceptions in Project Reactor"

class ReactiveJavaTutorial { public static void main(String[] args) { Flux.just(2, 7, 10) .concatWith(Flux.error(new RuntimeException(“Exception occurred”))) .concatWith(Mono.just(12)) .log() .subscribe(); } } Output: reactor.Flux.ConcatArray.1 : onSubscribe(FluxConcatArray.ConcatArraySubscriber) reactor.Flux.ConcatArray.1 : request(unbounded) reactor.Flux.ConcatArray.1 : onNext(2) reactor.Flux.ConcatArray.1 : onNext(7) reactor.Flux.ConcatArray.1 : onNext(3) reactor.Flux.ConcatArray.1 : onError(java.lang.RuntimeException: Exception occurred) reactor.Flux.ConcatArray.1 : java.lang.RuntimeException: Exception occurred at com.example.demo.DemoApplication.main(DemoApplication.java:14) ~[classes/:na]   You can see that element…

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by 0 comments on "doOn Callbacks in Project Reactor"

class ReactiveJavaTutorial { public static void main(String[] args) { Flux.just(“data1”, “data2”, “data3”) .doOnSubscribe(subscription -> System.out.println(“Subscription: ” + subscription)) .subscribe(); } } Output: Subscription: reactor.core.publisher.FluxArray$ArraySubscription@72bca894 doOnNext() method class ReactiveJavaTutorial { public static void main(String[] args) { Flux.just(“data1”, “data2”, “data3”) .doOnNext(data -> System.out.println(“Data: ” + data)) .subscribe(); } } Output: Data: data1 Data: data2 Data: data3 doOnComplete()…

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by 0 comments on "Combine Flux and Mono Publishers"

class ReactiveJavaTutorial { public static void main(String[] args) { Flux<String> firstFlux = Flux.fromArray(new String[]{“a”, “b”, “c”}); Flux<String> secondFlux = Flux.fromArray(new String[]{“d”, “e”, “f”}); // combine two Flux Publishers Flux<String> combinedFlux = Flux.concat(firstFlux, secondFlux); // subscribe and print the elements of a combined Flux combinedFlux.subscribe(element -> System.out.print(element + ” “)); } } Output: a b c…

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by 0 comments on "Transform Flux and Mono Using Operators"

class ReactiveJavaTutorial { public static void main(String[] args) { Flux.fromArray(new String[]{“Tom”, “Melissa”, “Steve”, “Megan”}) .map(String::toUpperCase) .subscribe(System.out::println); } } Output: TOM MELISSA STEVE MEGAN class ReactiveJavaTutorial { public static void main(String[] args) { Flux.fromArray(new String[]{“Tom”, “Melissa”, “Steven”, “Megan”}) .filter(name -> name.length() > 5) .map(String::toUpperCase) .subscribe(System.out::println); } } Output: MELISSA STEVEN   Note: Reactive Streams are immutable.…

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by 1 comment on "Subscribe to Flux in Java Reactor"

class ReactiveJavaTutorial { public static void main(String[] args) throws InterruptedException { // Create a Flux Flux<String> flux = Flux.just(“data1”, “data2”, “data3”); // Subscribe to a Flux and print the elements flux.subscribe(System.out::println); } } Output: data1 data2 data3   When we call the subscribe(), we are telling the Publisher to start sending data. class ReactiveJavaTutorial {…

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by 0 comments on "Create a Flux in Java Reactor"

import reactor.core.publisher.Flux; class ReactiveJavaTutorial { public static void main(String[] args) throws InterruptedException { // create an empty Flux Flux flux1 = Flux.just(); // create a Flux that will hold only one value Flux<String> flux2 = Flux.just(“data”); // create a Flux that will hold multiple values Flux<String> flux3 = Flux.just(“data1”, “data2”, “data3”); } } import reactor.core.publisher.Flux;…

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