java

In this tutorial, you will learn how to write a JUnit test that validates whether the method under test throws the correct exception. The tutorial includes examples for both JUnit 5 and JUnit 4. For video lessons, check out my video course: Testing Java with JUnit and Mockito. Let’s begin with JUnit 5 version first.…

Read More Test for Exception in JUnit 5 and JUnit 4

In this tutorial, I am going to share with you a few different techniques you can use to iterate over a collection in Java. Iterating ArrayList with Enhanced For-Loop List<String> names = new ArrayList<>(); names.add(“Sergey”); names.add(“Bill”); names.add(“John”); for(String name: names) { System.out.println(name); } Output: Sergey Bill John We declare a List of String objects named…

Read More Iterating over Collections in Java: Examples

Optional<T> findFirst() class Test { public static void main(String[] args) { List<Integer> numbers = new ArrayList<>(Arrays.asList(3, 7, 9, 12)); Optional<Integer> resultOptional = numbers.stream().findFirst(); if (resultOptional.isPresent()) { // checking if Optional contains any value System.out.println(“The first element in the stream is: ” + resultOptional.get()); // getting the value from Optional } else { System.out.println(“The stream is…

Read More Streams – findFirst() operation

Learning how to convert Java objects into JSON and vice versa can be very helpful for your work as a full-stack mobile app developer. In this blog post, I will share some code examples that will help you with the most common tasks you’ll encounter when working with JSON and Java. I will cover the…

Read More Convert Java into JSON and JSON into Java. All Possible Examples.

The Java Virtual Machine (JVM) is an integral part of the Java platform and is responsible for executing Java code. It provides a platform-independent environment for running Java applications, allowing developers to write code once and run it anywhere. Understanding how the JVM works is essential for Java developers to optimize performance and ensure the…

Read More Java Virtual Machine (JVM): The Complete Guide

In addition to the Java Runtime Environment (JRE), the JDK includes the following components: Compiler The Java compiler is used to convert Java source code into bytecode that can be executed on the Java Virtual Machine (JVM). A compiler is a command-line tool that takes a .java file as input and produces a .class file…

Read More JRE, JDK, and JVM: Understanding Differences and Uses

Programming languages like Java rely on the use of data types to manage and manipulate data in a program. Data types are a fundamental concept in programming and understanding them is crucial to becoming a proficient Java developer. Java has two main categories of data types: primitive data types and reference data types. Primitive data…

Read More Java Data Types: The Complete Beginner’s Guide