Private Field

[Alton Hernandez]

Note that a private field of a superclass might be accessible to a subclass (for example, if both classes are members of the same class).

This is a quote from JLS(8.3).
Do you know what this mean? Can you give an example?

[Corey McGlone]

How's this for an example:

public class Test
{
    private int someInt = 1;
    
    class InnerClass extends Test
    {
        public void doIt()
        {
            System.out.println(someInt);
        }
    }
    
    public static void main(String[] args)
    {
        InnerClass ic = new Test().new InnerClass();
        
        ic.doIt();
    }
}
 
// Output
 
1

Notice that the subclass can access the private member of the superclass because the subclass is also an inner class of the superclass.
I'm not really sure when you'd ever need to do something like this, but, as with most things you run into with the SCJP cert, you need to know what can be done, not necessarily what should be done.
I hope that helps,
Corey
[ June 06, 2003: Message edited by: Corey McGlone ]

[Praful Thakare]

Note that a private field of a superclass might be accessible to a subclass (for example, if both classes are members of the same class).
My be it means something like this ....
public class test
{
class t1
{
private int i=100;
}
class t2 extends t1
{
public void m()
{
t1 ob=new t1();
System.out.println(ob.i);
}
}
}

[Alton Hernandez]

Hi Corey,

Notice that the subclass can access the private member of the superclass because the subclass is also an inner class of the superclass.

Thanks for the reply.
But I still have a question:
Is the outer class considered the superclass of the inner class?
In that phrase(JLS 8.3), I was thinking along the line of 'extended' classes, because the paragraph before that, it was talking about inheritance.
Al

[Anupam Sinha]

Hi Corey
I think that the example you have given doesn't involes a subclass. I am posting a code that shows the subclass accessing a private member of the superclass.

public class test
{
 private String str="outer";
 public static void main(String args[])
 {
  test t=new test();
  t.inclassmeth(); 
 }
 class inner extends test
 {
  void showstr()
  {
   System.out.println(str);
  }
 }
 void inclassmeth()
 {
  inner it=new inner();
  it.showstr();
 }
}

[Alton Hernandez]

Hi Praful,
I think that's the right example

[Corey McGlone]

Is the outer class considered the superclass of the inner class?

Sorry about that, I modified the code above. Apparently, when I was copying my code for the reply, I forgot to attach the "extends Test" clause. Regardless, the code produces the same output. Sorry about that.
Corey

[Marlene Miller]

class Outer {
   class A {
      private int x;
   }
   class B extends A {
        
//    int y = x;  //compiler error x: has private access in Outer.A
      int z = super.x;  //you could also say ((A)this).x
   }
}

Since x is private, B does not inherit x.
However, x is accessible to B.

[Marlene Miller]

A practical example might be where the inner classes are declared public, something like this:

public class Outer {
   public class A {
      private int x;
      // more code here
   }
   public class B extends A {
      int z = super.x;
      // more code here
   }
   public A getA() {
      return new A();
   }
}