can anyone explain to me the output of this code

[vuthlarhi donald]

  
class Bird {
  { System.out.print("b1 "); }
  public Bird() { System.out.print("b2 "); }
}
class Raptor extends Bird {
  static { System.out.print("r1 "); }
  public Raptor() { System.out.print("r2 "); }
  { System.out.print("r3 "); }
  static { System.out.print("r4 "); }
}
class Hawk extends Raptor {
  public static void main(String[] args) {
    System.out.print("pre ");
    new Hawk();
    System.out.println("hawk ");
  }
}  

[Ulf Dittmer]

That's kind of an open-ended question. Which part of the output are you having trouble understanding?

[vuthlarhi donald]

here is the output r1 r4 pre b1 b2 r3 r2 hawk
but I was expecting pre to be printed first!!

[Mark Freeman]

r1 and r4 appear before pre, since they are part of static init blocks in Raptor. They execute as soon as the class is loaded, even without an instance being created. Note that Hawk extends Raptor, so the Raptor class is loaded when you ran "java Hawk" from the command line.

[Shiraz Khan]

r1 r4 pre b1 b2 r3 r2 hawk

Whenever a class is loaded, all the static initialiser blocks are excuted.
Next when you create an object of the class, first of all the instance initialiser blocks are executed and then constructor runs. At the time of running constructor, the implicit super() call to superclass consctrucor is invoked.

So when the classes are loaded "r1" and "r4' get printed, then at main method -> print "pre" . Then implicit constructor of Hawk calls super() to run Raptor(), which in turn calls Bird(). Before creating Bird object, the instance initialiser block is executed and "b1" gets printed. Then constructor runs and "b2" gets printed. It comes back to Raptor constructor where instance initialiser block gets excuted and "r3" is printed, then "r2" and finally "hawk" in main.