Installing the command-line executable

Assuming you have Rust/Cargo installed, run this command in a terminal:

cargo install java2pyi

It will make the java2pyi command available in your PATH if you've allowed the PATH to be modified when installing Rust. cargo uninstall java2pyi uninstalls.

Back to the crate overview.

Readme

java2pyi

project-image

Java‑to‑PYI is a Rust tool that parses Java source into a preprocessed AST and generates Python stub files (.pyi) with type definitions only. It was originally designed to generate class declarations to provide accurate type hints in the Telegram codebase when developing Exteragram plugins.

Installation from `crates.io`

cargo install java2pyi

Building from source code and installation steps

Clone this repo

git clone https://github.com/n08i40k/java2pyi

Compile and install

cargo install --path .

Usage example

Clone OpenJDK source code (required for all use-cases, otherwise, non-promitive java types won't be resolved)

git clone https://github.com/openjdk/jdk

Remove sample file from OpenJDK source code

rm ./jdk/src/java.base/share/classes/java/lang/snippet-files/ProcessExamples.java

Clone Telegram for Android source code

git clone https://github.com/DrKLO/Telegram

Create directory for stub files

mkdir stubs

Start generator

java2pyi -i ./jdk/src/java.base/share/classes/java/ -i ./Telegram/TMessagesProj/src/main/java/ -o ./stubs

Where -i is directories with .java files and -o is output directory for generated stubs.