Stuff I hope you never have to know about Java, Vol. 1, No. 1

import java.lang.reflect.Modifier;

public interface X {
    interface Y { /* ... */ }
}

interactive> Modifier.isPublic(X.Y.class.getModifiers())
true

Y is implicitly public, apparently -- just like methods and fields on X would be.
Written on January 5, 2010