A question on forward referencing.

[neha kanwal]

Can anyone please let me understand how the result is comes out to be 0 in the following code.

1. How the output comes out to be 0.
2. If I replaces private int i = giveMeJ(); with private int i = j;, I get compilation error due to forward referencing but why not in the earlier case.

public class AQuestion 
{ 
     private int i = giveMeJ(); 
     private int j = 10; 
 
     private int giveMeJ() 
     { 
          return j; 
     } 
 
     public static void main(String args[]) 
     { 
          System.out.println((new AQuestion()).i); 
     } 
}

Thanks,
Neha

[Sanjeev Kulkarni]

Neha,

1)
When you invoke (new AQuestion()).i in your main() method, the result is the value of that 'i' gets initialized with inside the constructor, whose body looks like this:

public AQuestion()
{
i = giveMeJ();
j = 10;
}

So, when 'i' tries to get the value from giveMeJ(), 'j' shouldn't have been initialized to 10, rather it would have the 0, the default value for an 'int'. So, i = 0 and the same would be printed.

One Important Point is: The instance variables get initialized in the order
they're read. So, if it were:

private int j = 10;
private int i = giveMeJ();

Then, you would get output as 10.

2) Forward referencing occurs because you're trying to assign a variable to value of some other variable that doesn't exist at that point at all!

Cheers!
Sanjeev

[Barry Gaunt]

Please search this forum for "giveMeJ". This question of forward or not forward referencing has been discussed before.