Java from Scratch in 2025: A Detailed Guide for Beginners

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Introduction to Java: Why is this language relevant in 2025?

Java is one of the most stable and in-demand programming languages in the world. Despite the emergence of new technologies, Java continues to hold leading positions in enterprise development, the mobile ecosystem (Android), and backend systems. In 2025, Java remains a reliable choice for those who want to start a career in IT.

Why should you start with Java today?

Huge community — millions of developers and thousands of libraries.
Platform independence — code runs on any OS thanks to the JVM (Java Virtual Machine).
High salary — Java developers are among the top earners.
Career growth — from Junior to Software Architect.

This article is your first step. We will cover what you need to install, how to write your first program, and which concepts a beginner should master.

Step 1: Installing JDK and Setting Up the Development Environment

What is JDK?

JDK (Java Development Kit) is a set of tools for Java development. It includes a compiler (javac), a virtual machine (java), and standard libraries.

How to Install JDK 21 (LTS) in 2025

Go to the official website Adoptium (recommended OpenJDK distribution).
Download the installer for your OS (Windows, macOS, Linux).
Run the installation and follow the instructions.
Verify the installation in the terminal (command line):

java --version

If you see the version openjdk 21.0.x — everything is ready.

Choosing an IDE (Integrated Development Environment)

For beginners, the best options are:

IntelliJ IDEA Community Edition — free, powerful, with hints.
VS Code — lightweight, requires installing the Extension Pack for Java plugin.

Install any of them — and you can start coding.

Step 2: Your First Java Program

Traditionally, you start with "Hello, World!". Create a file Main.java and write the following code:

public class Main {    public static void main(String[] args) {        System.out.println("Hello, Java 2025 world!");    }}

Code breakdown:

public class Main — class declaration. The file name must match the class name.
public static void main(String[] args) — the entry point of the program.
System.out.println() — prints text to the console.

Compilation and Execution

Open a terminal in the folder with the file and run:

javac Main.javajava Main

The console should display: Hello, Java 2025 world!

Step 3: Java Syntax Basics for Beginners

Variables and Data Types

Java is strongly typed. This means every variable has a fixed type.

public class Main {    public static void main(String[] args) {        // Integers        int age = 25;        long bigNumber = 10000000000L;

        // Floating-point numbers        double price = 99.99;        float discount = 15.5f;

        // Characters and strings        char grade = 'A';        String name = "Anna";

        // Boolean type        boolean isJavaFun = true;

        System.out.println("Hello, " + name + "! You are " + age + " years old.");    }}

Basic types: