OpenJDK 13.0.1 Sandbox • Automated Testcases • Free Online IDE

Online Java (OpenJDK) Compiler

Write, compile, and execute Java (OpenJDK) programs directly in your browser. Auto-check your code against custom standard inputs (stdin) and automated test cases. Free, instant, and no login required.

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Free Online Code Compiler

Welcome to FlareBox Online Compiler. Write, compile, and execute code in Java (OpenJDK) directly in your browser. No setup, installation, or login required.

Language:Java (OpenJDK)
Version:OpenJDK 13.0.1
File Extension:.java
Execution Limit:8.0 Seconds / 256MB
What you can do:
AI Problem Generator
Generate custom coding interview problems with test cases on demand.
Automated Test Case Engine
Check your code against multiple inputs and get instant diff feedback.
Zero Login Required
Free instant compilation for 8+ popular programming languages.
solution.java
Press Ctrl+Enter to run
Loading FlareBox Enterprise Editor...
Terminal Output
Click "Run Code" or press Ctrl+Enter to execute.
Your code will be evaluated against test cases and results will appear here.

Java (OpenJDK) Coding Tips & Quick Reference

Helpful syntax patterns and I/O tips for competitive programming in Java (OpenJDK).

Class Name Requirement

Always name your public class 'Main' so the runner can locate the entry point.

public class Main {
    public static void main(String[] args) {
        // Code here
    }
}

Fast Input with BufferedReader

Use BufferedReader instead of Scanner for large input sets.

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
String line = br.readLine();

Java (OpenJDK) Compiler FAQs

Common questions about compiling and debugging Java (OpenJDK) on FlareBox.

What should the public class name be in Java?

The main entry point class must be named 'Main' (public class Main).

Are Java standard collections and utilities supported?

Yes, all standard Java packages (java.util, java.io, java.math, etc.) are fully supported.

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