All about CLASS Files

The CLASS file type is primarily associated with Java Development Kit.

CLASS	File extension: CLASS
	File type:	bytecode

What is a CLASS file

CLASS files mostly belong to Java Development Kit by Oracle. A CLASS file contains bytecode compiled from source code written in Java programming language. Bytecode is a collection of compact numeric code which can be read and executed by the Java Virtual Machine (JVM) on any Java compatible platform. The Java Compiler (javac) in Java Development Kit creates a CLASS file while JVM executes it. Java bytecode saved in CLASS files are usually compressed into a JAR archive before they are deployed. Another type of CLASS file contains a program written in Gambas programming language. This file can be executed by the compiler in Gambas integrated development environment.

How to open a CLASS file

You need a suitable software like Java Development Kit to open a CLASS file. Without proper software you will receive a Windows message "How do you want to open this file?" or "Windows cannot open this file" or a similar Mac/iPhone/Android alert. If you cannot open your CLASS file correctly, try to right-click or long-press the file. Then click "Open with" and choose an application. You can also display a CLASS file directly in the browser:. Just drag the file onto this browser window and drop it.

Online CLASS Text Viewer

Choose your .class file to analyze

or drag and drop it here

Online File Viewer

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CLASS file format:

A file format defines how the data in the file is structured. Each file format has a unique extension and almost always a unique signature. For example, Microsoft Word documents have the extension .docx and the signature (usually the first 3 characters in this file) PK. File extension, signature and file format must match; otherwise errors will occur when the file is opened. So you need a detailed analysis of a file to find out the format and the associated program. Our evaluation of the CLASS files looks like this:

CLASS is a very common file type and primarily uses a special format that can be read by various programs. The two most popular formats are as follows:

• 95% of all CLASS files belong to Java bytecode. The contents of these files are partially readable with a text editor. The files are 480 bytes to 10 KB in size, with a median of 2 KB. The file type was developed 10 years ago and is still in use today. Certain words are almost always found in the files, such as lang, <init>, java and Ljava. Files like these are sometimes connected to data, info, handler, config, manager, client, impl, command, message, service, loader and type.
• 1% of all CLASS files use the same file format, which have the signature LID , TYPE , . The contents of these files are easily readable with a text editor. The file size is in the range of 160 bytes to 3 KB. Several words can almost always be found in the files, e.g. LID and TYPE.

The remaining 4% of all CLASS files are different files with different signatures. These files are often connected to action, user, utils, installer, account, entity, book, list or view. You can get all the details of your CLASS file by dragging it onto this page or by clicking the button "Choose your .class file to analyze" above.