Labels

[K Anshul]

The following code works

  void crazyLoop()
   {
  int c = 0;
      JILL: System.out.println(c);      
  JACK: while (c < 8)
     {
    if (c > 3) break JACK; else c++;
    }
 
   } 

but the follwoing doesn't

 void crazyLoop()
   {
  JILL: int c = 0;
       System.out.println(c);      
  JACK: while (c < 8)
     {
    if (c > 3) break JACK; else c++;
    }
 
   }
 

Please tell me the reason for this.

[Victor Santos]

void crazyLoop() { JILL: int c = 0; System.out.println(c); JACK: while (c < 8) { if (c > 3) break JACK; else c++; } }

Hi !
in the second code , you are declaring int c at scope of label JILL, so it is visible only in this label . You can not mention variable c in Label JACK !
I hope this is the problem

[K Anshul]

I don't think that's the problem. I thought labels work for loops only. But i first code Jill label is not used for loop then why does it work?

[Chris Allen]

Labels can be placed on any Java statement, not just looping statements. The effect of placing them on non looping constructs is the limitation of scope they apply to. I believe Victor is correct in his scope comment as from the JLS (14.7):

The scope of a label declared by a labeled statement is the statement immediately enclosed by the labeled statement.

Since the code is not enclosed in any braces, the scope is limited to the next statement ending with the semicolon. In this case, it really doesn't offer much in terms of functionality but it is legal.

[K Anshul]

Originally posted by victor santos:
void crazyLoop() { JILL: int c = 0; System.out.println(c); JACK: while (c < 8) { if (c > 3) break JACK; else c++; } }

Hi !
in the second code , you are declaring int c at scope of label JILL, so it is visible only in this label . You can not mention variable c in Label JACK !
I hope this is the problem

DOes that mean this should work

 public class Test{ 
   
  
        void crazyLoop() { 
JILL: int c = 0; 
}
  
} 
 

Now i am not using c anywhere ut still it doesn't work.

[Pal Sudarshan]

Hello,

I am not sure of the answer. Maybe I shouldn't be posting this, but here is what I think as of now. Maybe it will of help, but I AM NOT SURE of my own answer, okay. Just to let you know. :roll:

I think JILL: int c = 0 is not a statement.
Here is what I found online about statements in Java.
Click on the link below.
http://www.sniffer.net/bookshelf_do_sniffer/java/langref/ch06_js.htm

[vydhehi paruchuri]

According to JLS these are the statements:

Statement:
StatementWithoutTrailingSubstatement
LabeledStatement
IfThenStatement
IfThenElseStatement
WhileStatement
ForStatement

StatementWithoutTrailingSubstatement:
Block
EmptyStatement
ExpressionStatement
SwitchStatement
DoStatement
BreakStatement
ContinueStatement
ReturnStatement
SynchronizedStatement
ThrowStatement
TryStatement

StatementNoShortIf:
StatementWithoutTrailingSubstatement
LabeledStatementNoShortIf
IfThenElseStatementNoShortIf
WhileStatementNoShortIf
ForStatementNoShortIf

I think, Assignment statement is not pure statement.

You can compile and run the program by changing the label to

JILL:
{
int p = 0;
}
Thanks,

Vydhehi

[siva prakash]

Hi ,

void func() {

JACK : {
int i = 10 ;
}
}


works , but not

void func() {

JACK : int i = 10 ;
}


bye
siva