JVM/Java, are method accessibility rules enforced at runtime?

Question

I was curious about how the JVM works. Does the JVM acknowledge method accesibility rules like \'private\' protected or is that only done at compile time?

For examp

Answer 1

If you want to call this method from outside current class you could call private & protected methods using reflection.

Method m = RunX.class.getDeclaredMethod("test3");
m.setAccesible(true);
m.invoke(u);

however you can call this protected (and also private) method directly from main() without any issues.