File Extension Database

Open CLASS File

CLASS file extension is used to denote a compiled Java source code file. Prior to compilation, Java files are stored in plaintext with the JAVA file extension. In order to run Java programs, the source code must be compiled to create a CLASS file, which can then be loaded into a Java Virtual Machine to execute the application. Many Java applications will make use of multiple classes, each of which is stored and loaded as an individual CLASS file.

Before executing an application written in Java, it must first be compiled. This process converts the plaintext source code of the application into bytecode, which is a set of instructions designed to be executed by a software interpreter, which in this case is the Java Virtual Machine (JVM). Unlike JAVA source files, CLASS files are not human-readable and you cannot open CLASS file using a text editor.

Java is a cross-platform compatible language, meaning that the bytecode produced by compiling a program on one platform will be able to run on the Java Virtual Machine of any other platform.

A CLASS file contains several separate sections including access flags, constants, classes, interfaces and methods. CLASS files are used by a Java program to create objects and define their behaviour. However, as CLASS files are run as part of an executable program, they should only be loaded into a JVM if they are from a known, trusted source as the program could potentially be malicious software.

You can open CLASS files, load and run on any platform which has a Java Virtual Machine. Alternatively, some CLASS files can be decompiled into their original, human-readable source code and opened with a standard text editor or development environment. However, in most cases the reverse engineering of compiled software is illegal, and whether or not decompiling the code for educational use is allowed will depend on the license and usage terms attached to the program.

Typical CLASS application file locations:

C:\Windows\system32\NOTEPAD.EXE %1

Frequently associated Windows objects:

class_auto_file

How Can I Open CLASS File on Windows

We researched and learned that the best way to open CLASS file is to find a CLASS file in question in Windows OS File Explorer and double click on it to launch the corresponding application.
If a CLASS file is not opened in an application and you instead get a "Windows can't open a file" error message you should try looking for an application which can open the file in question.
If you know the application which can open CLASS file then run it and see if there is a File->Open main menu option in the application.
If you don't know the application which function as CLASS file opener then try to search online for "CLASS viewer", "application to open CLASS file" or "open CLASS file" queries in the search engine you like.
Install the application you found and check if it can open CLASS file

How Can I Open CLASS File on Mac OS

We recommend to find a CLASS file in question in Mac OS Finder and double click on it to launch the corresponding application.
If a CLASS file is not opened in a Mac OS application and you instead get a "There is no application set to open the file" error message you can click on "Search App Store" in the error dialog and Mac OS will show you applications compatible with CLASS file.
If you know the Mac OS application which can work as CLASS file opener you can choose the "Choose Application..." option in the error box to associate the file extension and open CLASS file in it.
If you don't know the application which can open CLASS file then try to search for "CLASS viewer", "application to open CLASS file" or "read CLASS file" queries in the online search engine you like.
Install the application you found and check if it can read CLASS file

How Can I Open CLASS File on Android

If you downloaded a CLASS file on Android device you can open it by following steps below:

In the Android apps list on your Android device find "My Files" or "File manager" app and tap to start it.
Tap on "Downloads" folder inside the app.
You should see your downloaded CLASS file in that folder.
Tap on the file. If Android device supports opening the file you downloaded it will open in the corresponding app.
If file does not open you can look for the corresponding app that can open the file by searching Android App Store for the "CLASS".
If you cannot open the file with the apps from Android App Store it is possible that the file could only be opened on desktop platforms such as Windows or Mac OS. Try searching for "CLASS viewer", "CLASS file reader" online and see if any desktop applications can open it.
It is also possible that the file you downloaded is outdated and is no longer supported.

How to Open CLASS File on iPhone or iPad

To open CLASS File on iOS device follow steps below:

We advies to open Files app on your iPhone or iPad device. You can find it by swiping down on the home screen and typing "Files" in the search bar.
Tap on the Downloads folder on the Files app home screen.
You will see all files that you recently downloaded. Tap on the CLASS file to view it.
If you have the right app that can open it it will automatically launch and open your file.
If you don't have the app which can open it you need to serch Apple app store for "CLASS". This way you can find apps which can open CLASS files.
If this doesn't help it is possible that your file could be opened only by the desktop application. To find an app which can open it on desktop look for "CLASS viewer" or "CLASS file" online in your favorite search engine.