What is .java?

.java files contain source code written in the Java programming language. Java is a class-based, object-oriented language designed to have as few implementation dependencies as possible, following the 'Write Once, Run Anywhere' (WORA) principle.

This quick guide explains when to use .java files, how to open them on any device, and how to share them instantly with FileXhost.

When to use .java files

You are building large-scale enterprise applications.
You are developing Android mobile apps.
You are creating cross-platform desktop applications (Minecraft was built in Java!).
You need a robust, strongly-typed language for backend systems.

How to open .java files

JAVA files are plain text and can be edited in any text editor, but are best managed in IDEs like IntelliJ IDEA, Eclipse, or VS Code. To run them, they must be compiled into bytecode.

Algorithm details

Java code is compiled by the Java Compiler (javac). It transforms the human-readable .java code into .class files containing bytecode. This bytecode is then executed by the Java Virtual Machine (JVM), which is why Java runs on any device with a JVM installed.

Browser & platform support

Direct: Not supported by modern browsers (Java Applets are deprecated).
Server: Extremely popular for server-side web applications (Spring Boot).

Format comparison

Feature	Details
Portability	Compiles to bytecode that runs on any OS with a JVM.
Performance	Faster than interpreted languages (Python/JS) but slightly slower than native C++.
Strictness	Statically typed and verbose, which helps prevent runtime errors.

How to create java files

IDEs: IntelliJ IDEA (New > Java Class).
Text Editors: Save file as 'MyClass.java'.
CLI: 'touch Main.java'.

How to convert java files

Compiler: 'javac Main.java' creates 'Main.class'.
Packaging: 'jar cvf app.jar *.class' creates a JAR file.
FileXhost: Upload to share source code.

Advantages & disadvantages

Advantages

Platform independence (Windows, Mac, Linux, Android)
Strong memory management (Garbage Collection)
Multi-threading support built-in
Huge ecosystem of libraries (Maven/Gradle)

Disadvantages

Verbose syntax (requires more code than Python)
Higher memory consumption compared to C/C++
Slower startup time (JVM warmup)

Tools & software

IDEs

IntelliJ IDEA, Eclipse, NetBeans, VS Code

Compilers

JDK (Java Development Kit), OpenJDK

Build Tools

Maven, Gradle, Ant

Frequently asked questions

Is Java the same as JavaScript?

No! They are completely different languages. Java is compiled and statically typed; JavaScript is interpreted and dynamically typed.

How do I run a .java file?

First, compile it with `javac filename.java`. Then, run the resulting class file with `java filename` (without the extension).

What is a .class file?

It is the compiled bytecode version of your .java file. This is what the computer actually executes.

Technical specs

File type: Code
Extension: .java
MIME type: text/x-java-source, text/java
Compression: Uncompressed
Max file size on FileXhost: Up to 25 MB per file on the free plan and up to 1 GB on Pro FileXhost accounts.

Upload your .java file to FileXhost to get a clean, shareable URL in seconds. View the file in a modern browser, protect access with optional settings, and let others download it without any confusing ads or cluttered file pages.

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