CLASS File Extension

What is CLASS file?

File with CLASS extension contains compiled source code written in Java programming language. CLASS file is generated by compiler from JAVA file that contains classes. CLASS file is thus the result of successful compilation process. Single CLASS file contains bytecode, that is, a binary code of given program that is executable when run by Java Virtual Machine (JVM).

Compilation process

CLASS files are generated automatically in the process of JAVA file compilation. JAVA files are the source files for any Java applications. CLASS file on the other hand contain bytecode that is platform independent. JAVA file can hold one or more classes, and each class gets its own CLASS file in the process of code compilation.

Additional information

Compilation of JAVA files into CLASS files is conducted using javac command included with JVM software package.

Most Java programming environments are capable of compiling CLASS files on the fly as programmers write the code.

Java Runtime Environment supports możliwe execution od CLASS files, but doesn’t allow its compilation since JRE doesn’t have javac command.

CAUTION

Because Java Virtual Machine is available in many versions, one must have in mind that not all CLASS files are compatible with all versions of the engine.

Programs which support CLASS file extension

Below you will find an index of software programs that can be used to open CLASS files divided into 4 categories according to system platform supported. CLASS files can be encountered on all system platforms, including mobile, yet there is no guarantee each will properly support such files.

Updated: 01/14/2020

How to open file with CLASS extension?

Problems with accessing CLASS may be due to various reasons. On the bright side, the most encountered issues pertaining to Java Class Format files aren’t complex. In most cases they can be addressed swiftly and effectively without assistance from a specialist. The following is a list of guidelines that will help you identify and solve file-related problems.

Step 1. Install Java Runtime Environment software

The most common reason for such problems is the lack of proper applications that supports CLASS files installed on the system. This issue can be addressed by downloading and installing Java Runtime Environment or different compatible program, such as Eclipse, dirtyJOE, DJ Java Decompiler. Above you will find a complete listing of programs that support CLASS files, classified according to system platforms for which they are available. One of the most risk-free method of downloading software is using links provided by official distributors. Visit Java Runtime Environment website and download the installer.

Step 2. Check the version of Java Runtime Environment and update if needed

You still cannot access CLASS files although Java Runtime Environment is installed on your system? Make sure that the software is up to date. Software developers may implement support for more modern file formats in updated versions of their products. If you have an older version of Java Runtime Environment installed, it may not support CLASS format. All of the file formats that were handled just fine by the previous versions of given program should be also possible to open using Java Runtime Environment.

Step 3. Set the default application to open CLASS files to Java Runtime Environment

After installing Java Runtime Environment (the most recent version) make sure that it is set as the default application to open CLASS files. The method is quite simple and varies little across operating systems.

The procedure to change the default program in Windows

• Right-click the CLASS file and choose Open with option
• Select Choose another app → More apps
• To finalize the process, select Look for another app on this PC entry and using the file explorer select the Java Runtime Environment installation folder. Confirm by checking Always use this app to open CLASS files box and clicking OK button.

The procedure to change the default program in Mac OS

• Right-click the CLASS file and select Information
• Find the Open with option – click the title if its hidden
• Select the appropriate software and save your settings by clicking Change all
• Finally, a This change will be applied to all files with CLASS extension message should pop-up. Click Continue button in order to confirm your choice.

Step 4. Ensure that the CLASS file is complete and free of errors

If you followed the instructions form the previous steps yet the issue is still not solved, you should verify the CLASS file in question. Problems with opening the file may arise due to various reasons.

1. Verify that the CLASS in question is not infected with a computer virus

If the CLASS is indeed infected, it is possible that the malware is blocking it from opening. Immediately scan the file using an antivirus tool or scan the whole system to ensure the whole system is safe. If the CLASS file is indeed infected follow the instructions below.

2. Check whether the file is corrupted or damaged

If you obtained the problematic CLASS file from a third party, ask them to supply you with another copy. It is possible that the file has not been properly copied to a data storage and is incomplete and therefore cannot be opened. It could happen the the download process of file with CLASS extension was interrupted and the file data is defective. Download the file again from the same source.

3. Check if the user that you are logged as has administrative privileges.

Sometimes in order to access files user need to have administrative privileges. Log out of your current account and log in to an account with sufficient access privileges. Then open the Java Class Format file.

4. Verify that your device fulfills the requirements to be able to open Java Runtime Environment

The operating systems may note enough free resources to run the application that support CLASS files. Close all running programs and try opening the CLASS file.

5. Verify that your operating system and drivers are up to date

Regularly updated system, drivers, and programs keep your computer secure. This may also prevent problems with Java Class Format files. It is possible that one of the available system or driver updates may solve the problems with CLASS files affecting older versions of given software.

Do you want to help?

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