The File Extensions Database

.CLASS File Extension

  • Developer by: Oracle
  • Category: Developer Files
  • Format: Binary

What is an .CLASS file?

.CLASS is Java Class File

A CLASS file is a compiled .JAVA file created by the Java compiler. It contains bytecode, which is binary program code that is executable when run by a Java Virtual Machine (JVM). CLASS files are commonly bundled into .JAR files, which are included in the $CLASSPATH environment variable for execution.

CLASS files can be compiled from JAVA files using the javac command, which is included with a JVM installation. Many Java IDEs, such as Eclipse, can compile CLASS files on the fly as developers write program code.

Since there are multiple versions of the JVM (e.g., 1.4, 1.5, and 1.6), some CLASS files may not be compatible with certain JVM versions. The Java Runtime Environment (JRE) can execute CLASS files, but it cannot compile them since it does not include the javac binary.

NOTE: Oracle acquired Sun Microsystems, the original developers of Java. The JRE and JVM are often used synonymously to refer to the platform that runs Java applications.

Programs that open Java Class File
Oracle Java Runtime Environment
Eclipse IDE for Java Developers
DJ Java Decompiler
Oracle Java Runtime Environment
Eclipse IDE for Java Developers
Oracle Java Runtime Environment
Eclipse IDE for Java Developers

How to solve problems with CLASS files

  • Associate the CLASS file extension with the correct application. On :
    Windows: Right click on any CLASS file and then click "Open with" > "Choose another app". Now select another program and check the box "Always use this app to open *.CLASS files". Mac: Right click (or Ctrl-click) the CLASS file, then click "Open with" > "Other...". Then choose another program and check the "Always Open With" box. Linux: Right click on the file, and select "Open with" and choose another program. iPhone: Tap the file. If you do not see an app to open the file, then tap Share "Share" and choose an app. Alternatively, save the file. Then open the Files app Files app. There long-press on the file, then release your finger. You will see a black menu bar. Then tap "Share" and select an app. Android: Tap the Settings icon on your smartphone, then tap on the Apps section. There tap the Options icon in the top right-hand corner of the screen to change the default apps.
  • Update your software that should actually open .CLASS is Java Class File. Because only the current version supports the latest CLASS file format. Search, therefore, e.g. on the Oracle manufacturer website after an available .CLASS is Java Class File update.
  • To make sure that your CLASS file is not corrupted or virus-infected, get the file again and scan it with antivirus software.