Private inner class question

[Yea Mua]

Hi all,

Private inner class&interface question... help~

public class PrivateInnerClassTest
{

        private interface InnerInterface
        {
               void fun();
        }

        private class InnerClass implements InnerInterface
        {
               void fun()          //2
               {
                      System.out.println("You Got it!");
               }
        }

        public static void main(String[] args)
        {
               InnerClass ic = new InnerClass();      //1
               ic.fun();
        }
}

Q:

At place //1 , the compiler says that I need to have an instance of PrivateInnerClassTest (outer class) to instantiate the inner class, like outer.new InnerClass(). But I am inside the outer class, and should not need that outer.new, but just new, right?

At place //2, the compiler says that I reduced the visibility of method fun when overriding. But as far as I can see, they both have default accessibility, not less restricted. So what is the problem then?

Thanks a lot!

[Seetharaman Venkatasamy]

Yea Mua wrote:
At place //1 , the compiler says that I need to have an instance of PrivateInnerClassTest (outer class) to instantiate the inner class, like outer.new InnerClass(). But I am inside the outer class, and should not need that outer.new, but just new, right?

to create an instance of an inner class , you need to have outer class instance.
so, InnerClass ic = new PrivateInnerClassTest().new InnerClass();

Yea Mua wrote:
At place //2, the compiler says that I reduced the visibility of method fun when overriding. But as far as I can see, they both have default accessibility, not less restricted. So what is the problem then?

by default, interface method has public visibility. so implementation class must give less restricted visibility(so in this case must be public) to implemented method.

[Yea Mua]

Hi Seetharaman,

Thanks for the kind help!

Based on your point and my personal understanding, I think these two questions can be addressed as below:

Place //1: For a "regular" inner class as shown in this example (not static inner class, not local inner class or anonymous inner class), it can be instantiated by using new operator within the outer class's non static code; It can also be instantiated by using outerObj.new within the outer class's static code or outside outer class.

Place //2: Default access modifier for method in interface is public. In constrast, default access modifier for overriden method in class is default. So overriding a method without explicitly declaring public is actually reducing visibility.