All About Class File 45.0

The original JVM class file structure established the binary contract for compiled Java code.

Binary milestone

Class File 45.0

The original JVM class file structure established the binary contract for compiled Java code.

First formatMajor 45Original JVM era

Compatibility meaning

Why the version number matters

The class file version is the binary compatibility signal that tells tooling and runtimes which generation of compiled Java bytecode they are dealing with.

This milestone is part of the steady one-step-per-release evolution of the Java class file contract.

javap -verbose MyClass.class
# look for: major version 45

Release context

What was happening around this milestone

First class file format

The original JVM class file structure established the binary contract for compiled Java code.

Continue through binary and runtime history

Common Class File Return to the class file timeline and compare this version with adjacent milestones. Common Java See the source-language side of the Java release associated with this class file version. Common JLS Compare source-language specification changes with binary-format evolution. Common JDK Use the platform view when you want to connect bytecode changes to tooling and runtime packaging.