The JVM is one of the most impressive pieces of software engineering, making Java incredibly fast for most workloads. But sometimes, "fast" isn't enough. For domains like scientific computing, AI, or processing massive volumes of text, we need to call highly-optimized native libraries written in C++ or Rust to gain a critical performance edge or access functionality not available on the JVM. For decades, this meant using the Java Native Interface (JNI)—a powerful but notoriously complex and unsafe bridge to the native world.

Enter Project Panama. With the Foreign Function & Memory (FFM) API, Java finally has a safe, supported, and elegant way to call native code, eliminating the need for brittle glue code and manual memory management. This talk puts it to the test with a classic Java challenge: the regular expression engine.

Join me for a practical, hands-on session where we will replace Java's capable but often-outperformed regex engine with Rust's highly optimized regex crate. We will walk through two implementations side-by-side: the "old way" with JNI and the "new way" with Project Panama. You will see firsthand how Panama simplifies interfacing with native code and improves safety. We'll cap it off with live benchmarks to compare the performance of both approaches against standard Java regex, helping you understand not just how to call native code, but also when it's truly worth the effort.

This talk presents the modern alternative to JNI: Project Panama. In the session, I will demonstrate how to use Rust's "regex" crate from Java using both JNI and Project Panama.

Attendees will not just learn about a new feature. They will see how it solves a real-world problem and learn when it's worth making the jump to native code—and when it's not.