Online Java Compiler

Write, compile, and run Java code directly in your browser with this free online compiler. Java is one of the most widely used programming languages in the world, powering everything from Android mobile apps to large-scale enterprise systems. This compiler lets you execute Java programs instantly without installing the JDK or setting up a development environment.

What is Java?

Java is a class-based, object-oriented programming language developed by Sun Microsystems in 1995 and now maintained by Oracle. It follows the "write once, run anywhere" philosophy thanks to the Java Virtual Machine (JVM). Java is strongly typed, meaning every variable must have a declared type, and it enforces strict object-oriented principles. Its reliability, portability, and extensive standard library have made it a top choice for enterprise software development worldwide.

Key Features

• Platform Independent: Compile once and run on any device with a JVM.
• Strong Typing: Catch errors at compile time rather than runtime.
• Object-Oriented: Enforces encapsulation, inheritance, and polymorphism.
• Rich Standard Library: Built-in collections, I/O, networking, and concurrency support.
• Garbage Collection: Automatic memory management prevents memory leaks.

Basic Java Syntax

public class Main {
    public static void main(String[] args) {
        // Variables and data types
        String name = "LabsICT";
        int year = 2025;
        boolean isFun = true;

        // Arrays and loops
        String[] languages = {"Java", "Python", "JavaScript"};
        for (String lang : languages) {
            System.out.println("Learn " + lang + " at LabsICT");
        }

        // Methods
        String greeting = greet("Developer");
        System.out.println(greeting);
    }

    static String greet(String user) {
        return "Welcome, " + user + "!";
    }
}

What Can You Build with Java?

Java is used extensively in enterprise software, powering banking systems, e-commerce platforms, and government applications. Android mobile development relies heavily on Java, with millions of apps built using the Android SDK. Backend developers use frameworks like Spring Boot and Jakarta EE to build REST APIs and microservices. Java is also used in big data processing with Apache Hadoop and Spark, embedded systems, scientific applications, and cloud-native development.

Try It Yourself

Type your Java code in the editor and click Run. The compiler supports standard Java features including classes, methods, loops, conditionals, arrays, and collections. The output will appear in the terminal panel. Use the Copy button to save your code, Reset to restore the default example, and Share to generate a shareable link.

Related Resources

Continue learning with our Java learning track, explore more online compilers, or browse our tutorials for step-by-step guides.