Java – why are private fields on enumeration types visible to containing classes?

public class Parent {

public class Parent {

    public enum ChildType {

        FIRST_CHILD("I am the first."),SECOND_CHILD("I am the second.");

        private String myChildStatement;

        ChildType(String myChildStatement) {
            this.myChildStatement = myChildStatement;
        }

        public String getMyChildStatement() {
            return this.myChildStatement;
        }
    }

    public static void main(String[] args) {

        // Why does this work?
        System.out.println(Parent.ChildType.FIRST_CHILD.myChildStatement);
    }
}

Are there any other rules for access control of parent and child classes participating in this enumeration, classes in the same package, etc? Can I find these rules in the specification?

Solution

It has nothing to do with enumeration - it has to do with private access from containing types to nested types

From Java language specification, section 6.6 1：

For example, this is also valid:

public class Test {

    public static void main(String[] args) {
        Nested nested = new Nested();
        System.out.println(nested.x);
    }

    private static class Nested {
        private int x;
    }
}

Interestingly, C # works a little differently - in C #, private members can only be accessed in the program text of types, including any nested types So the above java code will not work, but doing so will:

// C#,not Java!
public class Test
{
    private int x;

    public class Nested
    {
        public Nested(Test t)
        {
            // Access to outer private variable from nested type
            Console.WriteLine(t.x); 
        }
    }
}

... but if you just put console Change writeline to system out. Println, then it will be compiled in Java So Java is basically more relaxed than c#'s private members