Why is Java not running on Apple Silicon?

Question

I just got a MacBook Pro with the new M1 chip. I'd like to use native Apple Silicon code wherever possible.

I have a Java-based command-line program running and I noticed that this java process in Activity Monitor is of type 'Intel'.

The process's path is /usr/bin/java, which is supposed to be a Universal binary:

$ file /usr/bin/java
/usr/bin/java: Mach-O universal binary with 2 architectures: [x86_64:Mach-O 64-bit executable x86_64] [arm64e:Mach-O 64-bit executable arm64e]
/usr/bin/java (for architecture x86_64):    Mach-O 64-bit executable x86_64
/usr/bin/java (for architecture arm64e):    Mach-O 64-bit executable arm64e

So why is it running in Intel mode, and how can I run it natively?

Answer 1

/usr/bin/java is not the Java runtime. It is a wrapper that will launch a Java runtime. You can determine which Java runtime/JDK you're actually using by examining java --version.

Java versions are typically installed in /Library/Java/JavaVirtualMachines. You can download an Apple Silicon native JRE/JDK and copy it to that location and remove existing ones to ensure this.