how the execution happens?

[Ravindranath Chowdary]

Hi Friends,
     I want to know on what basis classes are loaded.
 
 class S
 {
     static final int I = 7;
 
     static
     {
         System.out.println("S");
     }
 }
 
 class T
 {
     static final Object S = null;
 
     static
     {
         System.out.println("T");
     }
 }
 
 class U
 {
     static final Object S = "s";
 
     static
     {
         System.out.println("U");
     }
 }
 
 class V
 {
     static final String S = "s";
 
     static
     {
         System.out.println("V");
     }
 }
 
 class W
 {
     static final String S = new String("s");
 
     static
     {
         System.out.println("W");
     }
 }
 
 class X
 {
     static final int I = 7;
 
     static
     {
         System.out.println("X");
     }
 }
 
 class Y
 {
     static final int I;
 
     static
     {
           I = 8;
           System.out.println("Y");
     }
 }
 
 class Z
 {
     static final Integer I = new Integer(7);
 
     static
     {
         System.out.println("Z");
     }
 }
 
 public class Main
 {
     public static void main(String[] args)
     {
         int s = new S().I;
         Object t = T.S;
         Object u = U.S;
         String v = V.S;
         String w = W.S;
         int x = X.I;
         int y = Y.I;
         Integer z = Z.I;
     }
 }
 
The o/p: S T U W Y Z
 
     Can you give me a clear idea why  X and V classes are not loaded?
 
Thanks,
Ravindranath.

[Jesper de Jong]

I didn't dig deep into this, but it's probably because of a compiler optimization: the variables S in class V and I in class X are compile-time constants, so in your main() method the compiler replaces "V.S" and "X.I" by the values of the constants - and so classes X and V don't need to be loaded anymore.

[Stan James]

I think that's what Tony was hinting in another post. That bothers me though. What if a third party changes the value of V.S and I plug in a new jar but don't recompile? I'll miss the change?

[Ernest Friedman-Hill]

Originally posted by Stan James:
I'll miss the change?

Yep. Therefore changing the value of a public static final field is not something to take lightly.