Java in 2025: A Complete Guide for Beginners from Scratch

Introduction: Why Java Remains Relevant in 2025?

Java is not just a programming language, but an entire ecosystem that has remained one of the most in-demand technologies in the world for over 25 years. In 2025, Java continues to confidently hold leading positions thanks to its reliability, cross-platform compatibility, and huge community. According to TIOBE and Stack Overflow rankings, Java is among the top three most popular languages, and the number of job openings for Java developers is only growing.

Why should you start learning Java right now? Firstly, it is the number one language for creating enterprise applications, banking systems, and Android development. Secondly, with the release of new versions (Java 21 LTS and higher), the language has become even more modern, concise, and convenient for beginners. Thirdly, Java is an excellent start for understanding object-oriented programming, which is the foundation for most modern languages.

In this article, we will thoroughly break down where to start learning Java in 2025, install all the necessary tools, write our first program, and give practical tips for a quick start.

1. Installing JDK and Setting Up the Environment

Before writing code, you need to install the Java Development Kit (JDK) — a set of tools for development. In 2025, I recommend using the latest stable version — Java 21 LTS or Java 22 (if you need the newest features).

Step 1: Downloading JDK

Go to the official Oracle website or use OpenJDK (free version). I recommend Eclipse Temurin (formerly AdoptOpenJDK) — it is completely free and community-supported.

• Download the installer for your OS (Windows, macOS, Linux).
• Run the installation, leaving all settings at default.
• Remember the installation path (usually C:\\Program Files\\Eclipse Adoptium\\jdk-21.0.2).

Step 2: Setting Environment Variables

For the system to find Java, you need to set the JAVA_HOME variable and add the path to bin in PATH.

For Windows:

• Open "System" → "Advanced system settings" → "Environment Variables".
• Create a new variable: JAVA_HOME = C:\\Program Files\\Eclipse Adoptium\\jdk-21.0.2.
• In the Path variable, add: %JAVA_HOME%\\bin.

For macOS/Linux:

Open the terminal and run the command:

export JAVA_HOME=/usr/lib/jvm/java-21-openjdk-amd64export PATH=$JAVA_HOME/bin:$PATH

Verify the installation with the command in the terminal:

java -versionjavac -version

If you see the Java version — everything is ready!

2. First Java Program: "Hello, World!"

Traditionally, learning any language starts with a program that prints a greeting. Let's create a file HelloWorld.java.

Creating and Compiling

Open any text editor (Notepad++, VS Code, or IntelliJ IDEA) and paste the following code:

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

Save the file with the name HelloWorld.java (the class name must match the file name).

Now open a terminal in the folder with the file and run the commands:

javac HelloWorld.java   // compilationjava HelloWorld         // run

If everything is done correctly, you will see the output:

Hello, world! I am learning Java in 2025!

Code Breakdown

• public class HelloWorld — class declaration. In Java, every program consists of classes.
• public static void main(String[] ar