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Initialization question

 
Greenhorn
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Hi to All, Please clarify why the first one compiles successfully, but the second one doesn't

1.


2.


Thanks in advance.
 
Ranch Hand
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because you are using j before it is declared and initialized. It is a case of forward referencing.
In the first code you are using a method to retrieve the value of j, which is runtime thing.
 
Neha Daga
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for any details on forward referencing read this
 
Natallia Bahlai
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Thanks a lot for clarifications and link. It's very useful.
 
Natallia Bahlai
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One more question: why the first one compile, the second one doesn't
1.


2.

 
Neha Daga
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again its forward referencing...in the second code you are using X before it is declared.
this topic has been discussed before on ranch read this
 
Natallia Bahlai
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How can we translate the rules to this code(for both variants: int i = this.j and int i = j; )


Rules are the following(form JLS):
The declaration of a member needs to appear before it is used only if the member is an instance (respectively static) field of a class or interface C and all of the following conditions hold:

* The usage occurs in an instance (respectively static) variable initializer of C or in an instance (respectively static) initializer of C.
* The usage is not on the left hand side of an assignment.
* C is the innermost class or interface enclosing the usage.
 
Neha Daga
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as I said this.j would be runtime thing but i = j is compile time.
 
Natallia Bahlai
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Thanks for reply!!! Everything is clear now.
 
Consider Paul's rocket mass heater.
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