Access a private variable from the superclass (JAVA)

Question

Ok so I have studied java all semester and thought I had a clear understanding about inheritance and super/sub classes. Today we were given as assignment for making a superclass called enemy, with sub classes of different types of enemies. I did everything fine and all of my subclasses are working, but when I went back to read the guidelines we must follow, I found this sentence:

"All member variables of the super class must be private. Any access to a variable must be done through protected methods in the subclasses."

From what I have learned, this makes no sense to me. If a variable is private within the superclass, doesn't that disallow access even from a subclass? The last part that talks about protected methods in the subclasses also doesn't make any sense to me. How does this help and/or allow any access whatsoever to the super class?

From what I've learned about inheritance, Below is what i thought was true:

                Access Levels
 Modifier    Class  Package Subclass    World
 public        Y      Y        Y        Y
 protected     Y      Y        Y        N
 no modifier   Y      Y        N        N
 private       Y      N        N        N

If I'm understanding something wrong here please do explain! I don't want to confront the instructor about giving us faulty instructions, if I'm the one not understanding it correctly!

Answer 1

The part

Any access to an a variable must be done through protected methods in the sub classes.

... just means that the subclasses have to call protected methods that are defined in the superclass. Since these methods are protected they can be accessed by the subclasses.

First you would define a base class like this:

public class Base {

    private int x;  // field is private

    protected int getX() {  // define getter
        return x;
    }

    protected void setX(int x) {  // define setter
        this.x = x;
    }
}

Then you would use it in your child class like this:

class Child extends Base{

    void foo() {
        int x = getX(); // we can access the method since it is protected.
        setX(42);  // this works too.
    }
}

Answer 2

Probably the sentence is not worded correctly, from what I understand it makes perfect sense to me :
1. the superclass has private fields and protected methods to access them
2. the subclasses access the fields by using that methods.