somebody please explain me this

[leena rane]

hi,
In round-up i saw this question:
In switch stmt,argument to the case label(case:argument) can be any variable which can fit within an int.
I said true,
i got it wrong.
The answer says:
false
the case argument must be either an int literal or an int -compatible variable which is a constant(i.e. static final)
Thanx in advance,
Best Regards,
leena.

[Cherry Sta. Romana]

Hi leena,
I think you were just confused about the question. The question refers to the argument following the case construct not the switch.
In the switch construct --> switch (expression) --> expression can be anything that is compatible to an int.
On the other hand, for the case construct, it has to be an int constant.
For example:
int a = 5;
int b = 10;
switch (a*2) // this is possible, value is evaluated
{
case 10: // should be a constant int
case b: // this is not possible since b is a var
}
I hope this helps.

[Guy Allard]

Also note that:
final int x = 20; // OK to use 'x' in 'case' because of 'final'
Regards, Guy

[Gagan Indus]

Nice explanation Cheery and
Very good point Guy Allard
please also note tht expressions involving final variables (along with literals only), which results in value assignable to the type of swicth-expression , can also be used as case labels

public class CaseTest 
{
public static void main(String args[]) 
{
final int x=1;
final int y=2;

switch(2) 
{
case 1 : break ; // do nothing 
case x*y : System.out.println(" Good Luck for ur exam!");break ;
}

}
}

output is :
Good Luck for ur exam!

even float , double final-variables can be used in the expression , but the final result has to be cast into int's ( byte , char , short , int )

public class CaseTest 
{
public static void main(String args[]) 
{
final int x=1;
final int y=2;
final float f = 1.0f;  // float variable , final
switch(2) 
{
case 1 : break ; // do nothing 
case (int) x*y*f : System.out.println(" Good Luck for ur exam!");break ;
}

}
}

still , output is :
Good Luck for ur exam!

------------------
Gagan (/^_^\)

[leena rane]

Thanx Cherry,Guy and Gagan 4 such nice explanation .
Now the point is clear to me!!
Best Regards,
leena

[Ashik Uzzaman]

Good explanation Gagan!
------------------
azaman