☕ Java OpenJDK Runtime

Free Online Java Compiler

Write, compile, and execute Java programs online instantly with OpenJDK runtime, Monaco IDE editor, and interactive input execution.

💻 Code Example (Java)

public class Main {
    public static void main(String[] args) {
        System.out.println("Hello, World from Online Java Compiler!");
        
        int sum = 0;
        for (int i = 1; i <= 5; i++) {
            sum += i;
        }
        System.out.println("Sum of 1 to 5: " + sum);
    }
}

Overview of Java Compiler

Java is an object-oriented, class-based programming language built around the principle of "Write Once, Run Anywhere" (WORA). Our Online Java Compiler lets you compile and run Java programs online without setting up JDK, environment paths (JAVA_HOME), or heavy IDEs like IntelliJ or Eclipse. Simply write your Java class, click Run, and view stdout and stderr output in seconds.

Key Platform Features

  • ⚡ Fast Sandbox Execution: Run code in under 2 seconds inside isolated Docker Linux containers.
  • 📝 Monaco Editor Engine: Experience auto-indentation, line numbers, and syntax highlighting powered by VS Code engine.
  • 📬 Interactive Stdin Input: Support for user input reading from stdin terminal interface.
  • 🔒 100% Secure & Private: Code runs purely in memory and is discarded after completion.
  • 📱 Zero Setup Required: Works seamlessly across laptops, tablets, and smartphones without downloads.

How to Compile & Run Code Online

  1. Select your preferred programming language from the top navigation bar.
  2. Type or paste your source code into the Monaco code editor.
  3. If your program requires user input, enter values into the interactive stdin terminal.
  4. Click the green Run Code button to compile and view your program output instantly.

Frequently Asked Questions (FAQ)

Q: Must my Java class be named Main?

By default, our Java runner uses class Main, but our pre-processor automatically detects public class names and adjusts them so your code compiles smoothly.

Q: Does this Java compiler support Object-Oriented Programming (OOP)?

Yes! You can define classes, methods, inheritance, interfaces, polymorphism, encapsulation, and exception handling.

Q: Can I test Java Scanner input online?

Yes! You can interactively provide inputs when java.util.Scanner or BufferedReader reads from System.in.