Java Online Compiler – Run Java Code Free

Online Java Compiler — Compile and Run Java Code Free

Our free online Java compiler lets you write, compile, and run Java code directly in your browser — no JDK setup, no IDE installation (Eclipse, IntelliJ), and zero cost. Whether you are starting a Java for beginners course, practicing Java coding, or testing algorithms, Anasufy IDE provides a full cloud JDK environment.

Java powers enterprise backends, Android applications, financial transaction systems, and large-scale web microservices. Learning Java equips you with strong Object-Oriented Programming (OOP) concepts, garbage collection understanding, and robust software design patterns.

Features of Our Java Compiler

• Multi-File Workspace: Create and organize multiple Java source files in a flexible virtual file tree.
• Custom Standard Input (stdin): Supply custom stdin parameters for Scanner and BufferedReader execution.
• One-Click Code Export: Download your .java source files directly to your computer with a single click.
• JDK 21 Runtime Support: Write modern Java featuring records, sealed classes, pattern matching, and text blocks.
• Fast JVM Execution: Compile .java source code and run bytecode in seconds.
• Standard Library Support: Built-in packages including java.util.*, java.io.*, java.math.*, and java.time.*.
• Clear Error Diagnostics: High-visibility line numbers and compiler exception details.
• Offline PWA App Support: Install as a PWA app to code Java programs offline.

Java Sample Program — OOP & Collections

import java.util.ArrayList;
import java.util.Collections;

public class Main {
    public static void main(String[] args) {
        ArrayList<String> languages = new ArrayList<>();
        languages.add("Java");
        languages.add("Python");
        languages.add("C++");
        
        Collections.sort(languages);
        System.out.println("Sorted Languages: " + languages);
    }
}

Frequently Asked Questions

What is an online Java compiler?

An online Java compiler is a web application that compiles Java source files into bytecode using a cloud JDK and executes the program on a JVM, returning output to your screen. Check Oracle Java Docs for complete API references.

Is this Java compiler free?

Yes, completely free with no registration or credit card required.

Can I pass custom standard input (stdin) to Java code?

Yes! Use the Input tab in the output panel to feed stdin inputs to Scanner(System.in) or BufferedReader.

Can I download my Java source files?

Yes, click the download icon in the top header bar to export your .java files directly to your computer.

Does Anasufy IDE support PWA offline installation?

Yes, install Anasufy IDE as a PWA app to access your coding environment and file workspace offline.

What should I name my main class?

Please name your public class Main so the Java compiler can locate the public static void main(String[] args) entry point correctly.

Can I practice Java without installing JDK on my computer?

Yes! Our online editor executes Java in the cloud, allowing you to code on any device without local JDK configuration.