zava

Mini Java VM in Zig v0.13.0

What it is

Zava is a Java^* VM implementation in Zig. This is a sister project of Gava which is using Go. The goal of Zava is to implement a couple of features which are not capable of doing by Go, such as GC and fine control of memory allocation.

The reference of the implement is JVM Spec 8 edition and it is supposed to be compatible with Java 8 bytecode.

* JAVA is a trademark of Oracle America, Inc.

Roadmap

Feature:
type system definition
class file parser
instructions interpretion
native methods bridge to support HelloWorld
class loading
bootstrap class loader
user defined class loader
string pool
basic reflection support (Class, Field, Method, Consutructor)
multi-thread and concurrency
garbage collector
profiling and Debugger integration

Non-functional:
sufficent unit test coverage
code readability and clear documentation of high-level design
mini ebook to describe how to evolve a mini VM from scratch
VSCode debugging extension

Get started

Download JDK and extract to jdk folder. The default class path is examples/classes and jdk/classes, so any classes located in the path can be loaded by zava.

• HelloWorld

zig build

./zava HelloWorld

Debugging

A VS code launch.json is configured for your debugging.

And after running the program, a zava.log is produced to trace the execution.

• info level: only method calls are logged
• debug level: per instruction executions are also logged with the context