Can I compile Java to native code?

Question

Is there any way to compile from Java to standalone (or library) machine code without requiring a JVM?

Answer 1

Yes!

Oracle has been working on the GraalVm, which support Native Images. Check here: https://www.graalvm.org/

Native Image The native image feature with the GraalVM SDK helps improve the startup time of Java applications and gives them a smaller footprint. Effectively, it's converting bytecode that runs on the JVM (on any platform) to native code for a specific OS/platform — which is where the performance comes from. It's using aggressive ahead-of-time (AOT) optimizations to achieve good performance.

See more:

• Summary
  https://www.graalvm.org/docs/getting-started/#native-images

• Demos: Native images for faster startup
  https://www.graalvm.org/docs/examples/native-list-dir/

• Detailed: 'Ahead-of-time Compilation'
  https://www.graalvm.org/docs/reference-manual/aot-compilation/

Answer 2

Yes, the JIT in the JVM does exactly that for you.

In fact it can produce faster code than compiling the code in advance as it can generate code optimised for the specific platform based on how the code is used at runtime.

The JVM is always involved even if a very high percentage is compiled to native code as you could load and run byte code dynamically.

Answer 3

Excelsior JET is a commercial Java to native code compiler.

Answer 4

There used to be a tool called GCJ that was part of GCC, but it's been removed. Now, all the links in the GCC site re-direct to their non-GCJ equivalents.

NB: the comments all refered to my original answer saying you can compile Java to native code with GCJ.