Installing Java & Setup — Java Tutorial

Installing the JDK

The Java Development Kit (JDK) includes the compiler (javac), the runtime (JVM), and the standard library. Download it from Oracle or use OpenJDK.

Example

# Check if Java is installed
java --version
javac --version

# macOS (with Homebrew)
brew install openjdk

# Ubuntu/Debian
sudo apt install default-jdk

# Windows: Download from oracle.com/java or adoptium.net

# Set JAVA_HOME environment variable
# Add to PATH: $JAVA_HOME/bin

Compile and Run

Java source files (.java) are compiled to bytecode (.class files), which runs on the JVM.

Example

// 1. Create a file: App.java
public class App {
    public static void main(String[] args) {
        System.out.println("Java is running!");
    }
}

// 2. Compile
// javac App.java  → creates App.class

// 3. Run
// java App  → executes the bytecode

// Single-file shortcut (Java 11+)
// java App.java  → compile and run in one step