instance initializer

[Deep Chand]

Hi all,
This may sound really dumb :-) but I'm confused about 'instance initializer'. I know that static initializer exists for the whole class i.e. run when the class is loaded. Constructor is executed when the instance is created. Then what's this 'instance initializer'?
any comments would be sincerely appreciated.
cheers,
Deep

[Dhanashree Mankar]

Originally posted by Deep Chand:
Hi all,
This may sound really dumb :-) but I'm confused about 'instance initializer'. I know that static initializer exists for the whole class i.e. run when the class is loaded. Constructor is executed when the instance is created. Then what's this 'instance initializer'?
any comments would be sincerely appreciated.
cheers,
Deep

___________________________________________________________________________
instance initializer is made to use in annonymous classes.
since annonymous classes are not having constructers ,instance initializers are used to initialize variables in annonymous classes.

[Deep Chand]

Does that mean they are only present in the anonymous classes and not anywhere else? Correct?
Thanks,
Deep

[Alton Hernandez]

Hi,
Instance initializer is like static initializer except that the codes within that block are invoked everytime an instance is created.
One of its use is to group codes that are common to all the constructor of the class. Example:
Instead of:

class S11 {
  int i;
  static {
    System.out.println("Static initializer");
  }
  {
    System.out.println("Instance initializer");
  }
  S11() {
    i++;
  }
  S11(int j) {
    i++;
  }
  public static void main (String [] args) {
    new S11();
  }
}

You can change it to:

class S11 {
  int i;
  static {
    System.out.println("Static initializer");
  }
  {
    [B]i++;[/B]
    System.out.println("Instance initializer");
  }
  S11() {}
  S11(int j) {}
  public static void main (String [] args) {
    new S11();
  }
}

You can also use it in anonymous class to initialize something in the instance.

class S11 {
  public static void main (String [] args) {
    Thread t = new Thread() {
       [B]{ setPriority(7); }[/B]
       public void run() {
         System.out.println("Priority:" + getPriority());
       }
    };
   t.start(); 
  } 
}

Hope this helps.
[ August 26, 2003: Message edited by: Alton Hernandez ]

[Deep Chand]

Thanks.