Java Programming

I have the following problem:

I want to have an interface, which is public, but has one method that I want to be protected. In the example below, methodB() is the method that I want protected. If I declare it as protected, the compiler complains. So I leave it without any decorations, as shown below.

public interface MyInterface {

    public int methodA();

    void methodB();

} 

Now, suppose I want to have a class that implements MyInterface. I try the following:

public class MyClass implements MyInterface {

    public int methodA() {
        return 42;
    }

    void methodB() {
        System.out.println("This is my secret.");
    }
}

The compiler complains again, saying that I am "attempting to assign weaker access privileges; was public". I seem to have no other choice than declare methodB in class MyClass as public.

My first question is: Please explain the logic here.

I want methodB to be declared in MyInterface, so that I may call within my own package:

o.methodB()

on any object o of type MyInterface, without having to cast it to a concrete class (that's the beauty of polymorphism).

My second question is: What shall I do?