java - A method with no statements inside and ends with a semicolon

So I came across a method like this in some source

public native void method();

There was code inside, but it was commented out,

/*MANUAL code code code */

The code looked a bit like C++.
So what does this mean? I know it does something because eventually it was called in the class...

Answer

That's a declaration for a native method, indicated by the native modifier, as explained in the Java Language Specification, section §8.4.3.4 native Methods .

You won't find its implementing code in Java, it's referring to code that's either in the C libraries that are part of the implementation of the JDK in use, or part of a native library bundled with the code you're studying. Refer to the JNI documentation to understand how this gets called from a Java program.