The @JsonIgnore annotation is used to mark a property or a method that should be ignored by Jackson when serializing or deserializing a Java object to or from JSON. This annotation belongs to the Jackson library, which is a popular library for working with JSON in Java. Spring Boot uses Jackson as the default JSON library,…
Read More @JsonIgnore Annotation in JavadataType[] arr; Where: int[] intArray = new int[5]; String[] arr = new String[3]; arr[0] = “value 1”; arr[1] = “value 2”; arr[2] = “value 3”;
Read More How to Declare an Array in Java?synchronized void method() {} public class SynchronizedInstanceMethodExample implements Runnable { public static void main(String[] args) { SynchronizedInstanceMethodExample runnable = new SynchronizedInstanceMethodExample(); new Thread(runnable).start(); // creates one thread new Thread(runnable).start(); // creates second thread } // Inherited run method from the Runnable interface @Override public void run() { try { // Calling the non-synchronized method print()…
Read More Java Synchronized Blocks and Methodsclass PrintArrayElementsExample { public static void main(String[] args) { int[] arr1 = {1, 7, 9, 5, 2, 8, 3}; String[] arr2 = {“Megan”, “Tom”, “Melissa”, “John”, “Steve”}; // print elements of the arr1 System.out.println(Arrays.toString(arr1)); // print elements of the arr2 System.out.println(Arrays.toString(arr2)); } } Output: [1, 7, 9, 5, 2, 8, 3] [Megan, Tom, Melissa, John,…
Read More Print Array Elements in Javapublic class SplitString { public static void main(String[] args) { String names = “Tom,Steve,John,Megan,Melissa”; // split string String[] arr = names.split(“,”); // print the size of the array System.out.println(arr.length); // print the elements Stream.of(arr).forEach(System.out::println); } } Output: 5 Tom Steve John Megan Melissa If you need a list, instead of an array, use the…
Read More Split a comma-separated String in Javaclass BreakOutOfLoop { public static void main(String[] args) { int[] arr = {1, 2, 3, 4, 5}; // iterate over array for (int i = 0; i < arr.length; i++) { if (arr[i] == 3) { // break out of the loop if the current value is equals to 3 System.out.println(“Breaking out of the loop!”);…
Read More How to break out of the loop in Java?class CheckIfArrayContainsValue { public static void main(String[] args) { String[] programmingLanguages = {“Python”, “Kotlin”, “Ruby”, “JavaScript”, “C#”, “Java”, “Flutter”}; for (String lang : programmingLanguages) { if (lang.equals(“Java”)) { System.out.println(“It does contain!”); break; // value found, exit the loop } } } } Output: It does contain! Here, we are iterating over the array, and…
Read More Check if Array Contains a Value in JavaOutput: Some String Here, we put the creation of the Scanner object into a try-with-resources because we want to close the Scanner after it reads all the data. We passed the “\\A” to tell the Scanner to read the entire input stream. import java.io.ByteArrayInputStream; import java.io.IOException; import java.io.InputStream; import java.nio.charset.StandardCharsets; class ConvertInputStreamToString { /** *…
Read More Convert InputStream to a String in JavaIn this tutorial, we will explore different methods to find duplicate elements in a Java array, including using nested loops, sets, streams, and hash tables. We will also discuss the time and space complexity of each method, so you can choose the most efficient one for your specific use case. Whether you’re a beginner or…
Read More How to Find Duplicate Elements in a Java Arrayclass EscapeDoubleQuotesInString { public static void main(String[] args) { String str = “Hello, I’m \”Steve\” and I am \”Java\” developer”; System.out.println(str); } } Output: Hello, I’m “Steve” and I am “Java” developer Escape double quotes in a JSON object in Java There are many cases where you might need to escape double quotes. In this…
Read More Escape Double Quotes in Java String<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;…
Read More Read and write Excel files in Java<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(); }…
Read More Testing with StepVerifier in Project Reactorclass 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…
Read More Implementing Backpressure in Project Reactorclass 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 : |…
Read More subscribeOn and publishOn operators in Project Reactorclass 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 : |…
Read More Reactor Execution Model – Threading and Schedulers