Skip to main content
Service phase: Beta

This service is still in development. Give us your feedback or view this page on the current PRONOM service.

Format

Java Class File

Summary

Name
Java Class File
Identifiers
PUID: x-fmt/415
Description
A file containing Java bytecode that can be executed on the Java virtual machine (JVM). A Java class file is usually generated by a Java compiler from a Java programming language source code file. Java is a high-level, class-based, object-oriented general-purpose programming language designed to have as few implementation dependencies as possible.
File extensions
class
Source
Digital Preservation Department / The National Archives

Relationships

Has priority over

Internal signatures

Java Class File

Note
Magic number (first four bytes) of every valid class file is 0xCAFEBABE

Byte sequences

Min Frag Length
Absolute from BOF
Offset
0
Max offset
None
Byte Sequence
CAFEBABE
Endianness
Little-endian

Changelog

  • Updated in V112

    Release date
    10 May 2023

    Java Class File: Updated format and signature names and descriptions. Submitted by Stadtarchiv Hof (Municipal Archives of Hof, Free State of Bavaria, Germany).

  • Updated in V92

    Release date
    20 September 2017

    Java Compiled Object Code: Gave priority over Alias Pix Image File due to rare edge-case clash conditions.