Static Initializers.

[Surya B]

Hi All,
Here is one more teaser if you have time to answer
What will be the result of attempting to compile and run the following class?
public class InitTest
{
static String s1 = sM1("a");
{
s1 = sM1("b");
}
static
{
s1 = sM1("c");
}
public static void main(String args[ ] )
{
InitTest it = new InitTest( );
}
private static String sM1(String s)
{
System.out.println(s) ; return s;
}
}
a)The program will fail to compile
b)The program will compile without error and prints a,c,b in that order when run.
c)The program will compile without error and prints a,b,c in that order when run.
d)The program will compile without error and prints c,a,b in that order when run.
e)The program will compile without error and prints b,c,a in that order when run.

[Anonymous]

is it b ?

[deekasha gunwant]

i also think it is b

[Harry Chawla]

What I understand is that answer should be c), printing a, b, c respectively.
[This message has been edited by Harry Chawla (edited August 02, 2000).]

[Amandeep Waraich]

I also think that the answer should be b.

[Surya B]

Hi All,
The answer is b,it prints a,c,b in that order.Here are some of the points:
First, static statements/blocks are called IN THE ORDER they are defined.
Next, instance initializer statements/blocks are called IN THE ORDER they are defined.
Finally, the constructor is called. So, it prints a, c an b in that order.
Surya

[Anonymous]

Originally posted by Surya B:
Hi All,
The answer is b,it prints a,c,b in that order.Here are some of the points:
1. First, static statements/blocks are called IN THE ORDER they are defined.
2. Next, instance initializer statements/blocks are called IN THE ORDER they are defined.
3. Finally, the constructor is called. So, it prints a, c an b in that order.
Surya

I want to add one more point here. After point 1, if the constructor has this() or super() that will be executed.
[ ofcourse there is none in Surya's example. But i just want to mention it]

This is the order
1. Static Initializer.
2. Constructor Header
3. Instance Initializer.
4. Constructor Code.

Folks, try out some code and correct me if I am wrong.

- Srini

[rajsim]

Hi Vasan,
You forgot about class and instance field initialization outside
initializer blocks.

[rajsim]

Here is the initialization sequence if you consider the
inheritance hierarchy.
1. When class is loaded
All static fields initialization and static initializers are
invoked from top down from Object down through inheritance
hierarchy to the class being loaded.

2. When an object is being created
Initialization is again done top-down from Object to the
class of the object being created.

Instance initialization is done in the following order:
a. Any field initializers and instance initializers
b. constructor
Here is a sample code demonstrating initialization sequence.

class P {
  static String s1 = G.str ( "Parent static field" );
  String i1 = G.str ( "Parent instance field" );
  static { String sb1 = G.str ( "Parent static initializer block" ); }
  { String ib1 = G.str ( "Parent instance initializer block" ); }
  P() { String ib2 = G.str ( "Parent Constructor" ); }
}
class C extends P {
  static String s1 = G.str ( "Child static field" );
  String i1 = G.str ( "Child instance field" );
  static { String sb1 = G.str ( "Child static initializer block" ); }
  { String ib1 = G.str ( "Child instance initializer block" ); }
  C() { String ib2 = G.str ( "Child Constructor" ); }
}
class G {
  static int n = 0;
  public static String str(String s) {
    System.out.println( ++n + "." + s );
return s;
  }
  public static void main ( String args[] ) {
    str  ( "accessing static variable" );
    String s = C.s1;
    str ( "constructing object" );
    new C();
  }
}

The output is:
1.accessing static variable
2.Parent static field
3.Parent static initializer block
4.Child static field
5.Child static initializer block
6.constructing object
7.Parent instance field
8.Parent instance initializer block
9.Parent Constructor
10.Child instance field
11.Child instance initializer block
12.Child Constructor
Please let me know if I missed out something