Getting Started with Java

Install Java, set up your development environment, and write your first Java program.

Java is a statically typed, object-oriented language that compiles to bytecode running on the Java Virtual Machine (JVM). It’s widely used for enterprise applications, Android development, and backend services.

Install the JDK

macOS (Homebrew):

brew install openjdk

Ubuntu / Debian:

sudo apt-get install default-jdk

Windows: Download the JDK from Adoptium or Oracle.

Verify the installation:

java -version
# openjdk version "21.0.1" ...

Version Management

Use SDKMAN! to manage multiple Java versions:

curl -s "https://get.sdkman.io" | bash
sdk install java 21.0.1-tem
sdk default java 21.0.1-tem

Switch versions per project:

sdk use java 17.0.9-tem

Build Tools

Maven

Maven uses a pom.xml to declare dependencies and build steps:

sdk install maven
mvn archetype:generate -DgroupId=com.example -DartifactId=myapp -DarchetypeArtifactId=maven-archetype-quickstart
cd myapp
mvn compile exec:java -Dexec.mainClass="com.example.App"

Gradle

Gradle uses a build.gradle file with a Groovy or Kotlin DSL:

sdk install gradle
gradle init --type java-application
./gradlew run

Hello World

Create HelloWorld.java:

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

Compile and run:

javac HelloWorld.java
java HelloWorld

Project Structure

A typical Maven project layout:

myapp/
├── pom.xml
└── src/
    ├── main/
    │   └── java/
    │       └── com/
    │           └── example/
    │               └── App.java
    └── test/
        └── java/
            └── com/
                └── example/
                    └── AppTest.java

IDE

IntelliJ IDEA — the most popular Java IDE (Community Edition is free)
VS Code — with the Extension Pack for Java
Eclipse — free, open-source IDE

Next: Java How-Tos