sd4j is a Stable Diffusion inference Java implementation using ONNX Runtime, optimized and ported from a C# implementation. It features a graphical user interface for generating images repeatedly and supports negative text input. Its purpose is to demonstrate how to use ONNX Runtime in Java and provide best practices for achieving good performance with ONNX Runtime. We will keep it synchronized with the latest ONNX Runtime version and update it appropriately as performance-related ONNX Runtime features become available through the ONNX Runtime Java API. All code is subject to change as this is a code example, and no APIs should be considered stable.