inner class

[Rishi Wright]

Hi 'LL..
I came across this code while searching for inner classes in javaranch.
class Test{
Test caller(boolean b){
class inner_c extends Test{
int i = 5;
void printval(){
System.out.println("initialized inner i " + i);
}
}
inner_c c = new inner_c();
return c;
}
void printval()
{
System.out.println("Inside Test1.printval()");
}
public static void main(String args[]){
Test t = new Test();
Test temp = t.caller(false);
temp.printval();
}
}
as per my knowledge inner_c is an local class defined in a method caller.
then temp is able to access printval() in inner_c(Not In Test class) as it is out of scope in the main methiod
thnx
rishi

[Anupam Sinha]

Hi Rishi
I don't really know whether I understood your question fully or not. Well here's my take at it.
Test caller(boolean b) returns a Test type of object which in this case is an instance of class inner_c.
So basically you can replace

Test t = new Test();
Test temp = t.caller(false);
temp.printval();

with

Test t = new Test().caller(false);
t.printval();

[ August 05, 2003: Message edited by: Anupam Sinha ]

[Alton Hernandez]

Hi Rishi,
The class inner_c, although a local class, can extend the Test class. So when it defines the method printval(), it overrides Test's printval() method. And when the call temp.printval() is made, polymorphism will still be at work. The method to invoked will be resolved a run-time, and in this case, it will resolve to inner_c's printval().
Hope this helps.
[ August 05, 2003: Message edited by: Alton Hernandez ]

[Rishi Wright]

Ok Alton ..that means if u extend any outer class(or any class outside that method )then local class will be still available as a subclass even we exit the method..is it so?? is this same for anonymus class also?
thnx
rishi

[Alton Hernandez]

Hi Rishi,
A little modification on the code will show you that this is also true for anonymous class:

class Test{
  Test caller(boolean b){
     [B] return  new Test() {
         int i = 5;
         void printval(){
            System.out.println("initialized inner i " + i);
         }
      };[/B]
  }
  void printval()
      { System.out.println("Inside Test1.printval()");}
  public static void main(String args[]){
      Test t = new Test();
      Test temp = t.caller(false);
      temp.printval();
  }
}