constructor

[meena latha]

Hi all

If we invoke a inner class using the instance of the outer class does the outer class constructor will also get invoked or not....

For example

public class A
{
  A()
    {}
   class B()
      {
         B(){}
      }
  public static void main(String[]arg)
  {
    A a = new A();
    a.new B();
    a.newB();
  }
}

Can anybody explain how many time A() is invoked.

Thanks In advance.
[ February 23, 2005: Message edited by: ramya jp ]

[Nathaniel Stoddard]

Once.

[Jay Pawar]

Ramya,
Simple test would be to put System.out.println statement in the constructor of the Outer class and observe the output.

[Barry Gaunt]

Ramya, you may like to try this variation of your code:

public class A
{
  A() {System.out.println("A()");}
  
  class B extends A  // Look what happens now!
  {
    B(){}
  }
  
  public static void main(String[]args)
  {
    A a = new A();
    a.new B();
    a.new B();
  }
}
  

[meena latha]

Hi all.
When u dont extend the class A then

 
       A a = new A();//line 1
          a.new B();//line 2
          a.new B();// line 3

line 1 will call the constructor of A.
Line 2 will invoke the constructor of B using an instance of A.
Line 3 does the same

But when we make
class B extends A
Then each time when we invoke the B() the superclass Constructor is also call.

I am not clear why this difference happens.Is it because only when we extend the B becomes the subclass of A.
If we dont extend then B is just a class inside a Class A and not a subclass.
Thanks in advance

[Barry Gaunt]

Ramya wrote:

Is it because only when we extend the B becomes the subclass of A?
If we don't extend then B is just a class inside a Class A and not a subclass?

Exactly.