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Learn Java 8 streams with an example - print odd/even numbers from Array and List

Example 1: Java 8 program to print odd numbers from a List   import java.util.Arrays; import java.util.List; import java.util.stream.Collectors; /*Java 8 Program to find Odd Numbers from a List*/ public class DriverClass { public static void main( String [] args) { List < Integer > numbers = Arrays. asList( 1 , 4 , 8 , 40 , 11 , 22 , 33 , 99 ); List < Integer > oddNumbers = numbers.stream(). filter(o -> o % 2 != 0 ). collect(Collectors.toList()); System.out.println(oddNumbers); } } 1. Initialize List using Arrays.asList() method. Java's built-in Arrays.asList() method converts an array into a list. This method takes an array as an argument and returns a List object. 2.  Java List interface provides stream() method which returns a sequential Stream with list of Integer as its source. 3. The Java stream filter() method allow
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Convert JSON String to Map and Map to JSON String with Jackson

In this section, we will show you h ow to c onvert JSON String to Map and Map to JSON String with Jackson. Note Jackson is a very popular and efficient java based library to serialize or map java objects to JSON and vice versa. Note JSON  (JavaScript Object Notation) is a lightweight format that is used for data interchanging. JSON  is built on two structures:  A collection of name/value pairs. In various languages, this is realized as an object, record, struct, dictionary, hash table, keyed list, or associative array.  An ordered list of values. In most languages, this is realized as an array, vector, list, or sequence. 1. Download Jackson < dependency > < groupId >com.fasterxml.jackson.core</ groupId > < artifactId >jackson-databind</ artifactId > < version >2.14.1</ version > </ dependency > In Jackson, we can use   mapper.readValue(json, Map.class)   to convert a JSON string to a   Map. 2. JSON string to Map Main.java import
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Spring boot video streaming example-HTML5

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Hello everyone, Today we will learn how to stream MP4 video using Spring Boot and Spring Web Flux.  The Source code download link is provided at the end of this post. New, Quarkus Practice User Interface   Project Structure: G radle(build.gradle) plugins { id 'org.springframework.boot' version '2.5.4' id 'io.spring.dependency-management' version '1.0.11.RELEASE' id 'java' } group = 'com.knf.demo' version = '0.0.1-SNAPSHOT' sourceCompatibility = '11' repositories { mavenCentral() } dependencies { implementation 'org.springframework.boot:spring-boot-starter-webflux' testImplementation 'org.springframework.boot:spring-boot-starter-test' testImplementation 'io.projectreactor:reactor-test' } test { useJUnitPlatform() } Service (VideoStreamingService.java) package  com.knf.demo.service ; import org.springframework.beans.factory.annotation. Autowired ; import org.springframew
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Best Free Java IDEs

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Java is the best programming language in the world. Java made this position by its simplicity, platform-independent, open-source, and its robust ecosystem of IDEs. Java Development IDEs support concrete and general objectives.   In this post, we will glean insights into different best Java IDEs to consider in the future development activities.     1.Eclipse       Eclipse is a free Java IDE for the developers. It is mostly inscribed in Java. Eclipse lets us engender various cross-platform Java applications for use on mobile, web, desktop, and enterprise domains. We can facilely cumulate multiple languages support and other features into any of our default packages, and the Eclipse Emporium sanctions for virtually illimitable customization and extension. An impressive amassment of implements can be facilely installed into our Eclipse desktop IDE, including GUI builders and implements for modeling, charting and reporting, testing, and more. We can utilize the Eclipse Rialto Client to find
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Spring Boot + JSP - Hello World Example

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In the section, we will create a project for Hello Word Example with Spring Boot and JSP. Note  A quick side note here is that JSP has limitations on its own and even more so when combined with Spring Boot. So, we should consider the following template engines as better alternatives to JSP.  Thymeleaf   FreeMarker   Mustache Groovy Technologies  used: Spring Boot 3.0.1 Spring 6.0.3 Maven Java 17 1. Creating a simple Spring Boot Application  First, open the Spring initializr https://start.spring.io/ Then, Provide the Group and Artifact name. We have provided Group name com.knf.dev.demo and Artifact spring-boot-jsp-helloworld . Here I selected the Maven project - language Java - Spring Boot 3.0.1 and add Spring web dependency.   Then, click on the Generate button. When we click on the Generate button, it starts packing the project in a .zip(spring-boot-jsp-helloworld.zip) file and downloads the project. Then, Extract the Zip file. 2. Final Project Directory 3. Project Dependencies For
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Java Stream API - How to convert List of objects to another List of objects using Java streams?

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In this section, we will show you how to convert a List of objects to another List of objects in Java using the Java streams map(). The ‘map’ method maps each element to its corresponding result. Java Stream API   The Java Stream API provides a functional programming approach over the object oriented capabilities of Java. It is used for processing collections of objects. The Stream in Java can be defined as a sequence of elements from a source List, Set or Array. Most of the stream operations return a Stream. This avails engender a chain of stream operations(stream pipe-lining). The streams withal support the aggregate or terminal operations on the elements. for example, finding the sum or maximum element or finding the average etc...Stream operations can either be executed sequentially or parallel. when performed parallelly, it is called a parallel stream.   Stream map() Method   The Java 8 Stream map() is an intermediate operation. It converts Stream<obj1> to Stream<obj2>
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Java 8 Stream - Remove duplicates from a list of objects based on a property

In this section, we will show you how to remove duplicates from a list of objects based on a single property.  In this example, we are getting the stream from the list and putting it in the TreeSet from which we provide a custom comparator that compares id, email, or salary uniquely.   Here we are going to remove duplicates based on the,  id(Long) property of the user  email(String) property of the user  salary(Double) property of the user User.java public class User { private Long id ; private String name ; private String email ; private String phone ; private Double salary ; public Long getId () { return id ; } public void setId ( Long id) { this . id = id; } public String getName () { return name ; } public void setName ( String name) { this . name = name; } public String getEmail () { return email ; } public void setEmail ( String email) { this . email = email; }
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ReactJS, Spring Boot JWT Authentication Example

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In this tutorial, we’ll create a user registration & login example using ReactJS, Spring Boot, Spring Security, and JWT authentication. You could download the source code from our Github repository, the download link is provided at the end of this tutorial. Technologies used Backend Technologies: Java 17 Spring Boot 2.7.0 Spring Security Spring Data JPA JWT H2 Database Frontend Technologies: React 17.0.1 Axios 0.27.2 Redux 4.0.5 Bootstrap 4.5.2 ReactJS - SpringBoot - JWT - Flow Backend Project Directory: Frontend Project Directory: Following is the screenshot of our application - User Registration: User Signin: Profile View: Access Resource: We will build two projects:  1. Backend:   spring-boot-security-jwt 2. Frontend: react-redux-jwt Project 1: spring-boot-security-jwt Pom.xml <?xml version = "1.0" encoding = "UTF-8" ?> <project xmlns = "http://maven.apache.org/POM/4.0.0" xmlns:xsi = "http://www.w3.org/2001/XMLSchema-instance"
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Google Cloud Storage + Spring Boot - File Upload, Download, and Delete

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In this section, we will learn  how to  create a simple spring boot application to perform different file operations such as upload, download, list, and delete files from the Google Cloud Storage. 1.  A little bit of Background Google Cloud Storage Cloud Storage is a managed service for storing unstructured data. Store any amount of data and retrieve it as often as you like. More Info - click here! Spring Boot Spring Boot makes it easy to create stand-alone, production-grade Spring-based Applications that you can "just run".  More Info - click here! 2. Create a GCP Project First, Sign into the Google console at  https://console.cloud.google.com . You can create a new project by first selecting the project dropdown in the top left and selecting " New Project ". Next, specify your GCP  Project name  and  Project ID . Then  Click on the " CREATE " button. Copy " Project ID " and keep it for future purposes. 3. Create a Google Cloud Storage bucket Fr
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Registration and Login with Spring Boot + Spring Security + Thymeleaf

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In this section, we will learn how to create user registration and login using Spring boot, Spring security, Thymeleaf, JPA, and H2DB. The GitHub repository link is provided at the end of this tutorial. You can download the source code. Technologies used: Spring Boot 2.5.5  Spring Data JPA  Spring Security  Thymeleaf  Maven 3+  Java 17  H2 Database   User Interface User Registration Authentication Failed Authentication success Sign out Final Project Structure: Complete pom.xml: <? xml version ="1.0" encoding ="UTF-8" ?> < project xmlns ="http://maven.apache.org/POM/4.0.0" xmlns: xsi ="http://www.w3.org/2001/XMLSchema-instance" xsi :schemaLocation ="http://maven.apache.org/POM/4.0.0 https://maven.apache.org/xsd/maven-4.0.0.xsd" > < modelVersion >4.0.0</ modelVersion > < parent > < groupId >org.springframework.boot</ groupId > < artifactId >spring-boot-starter-pare
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