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final keyword on variables

 
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public class Test8{
public static void main(String a[]){
byte b = 1;
char c = 2;
short s = 3;
int i = 4;

c = b; // 1
s = b; // 2
i = b; //3
s = c * b; //4
}
}
Which of the following are correct?
Error at 1
Error at 4

but here....

public class Test9{
public static void main(String a[]){
final byte b = 1;
char c = 2;
short s = 3;
int i = 4;

c = b; // 1
s = b; // 2
i = b; //3
s = c * b; //4
}
}
which of the following are correct?
error at 4.

can someone explain me the use of final here???
 
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from the JLS 4.12.4:

"We call a variable, of primitive type or type String, that is final and initialized with a compile-time constant expression (�15.28) a constant variable."



Note that if you leave off the initializer (= 1) you have a blank final, which is different.


final byte b = 1;



b is now a constant expression with a value known at compile time.

so, at 1 in the second example, it's exactly the same as putting "c = 1;"
at 4, you have a type mismatch error because of c.

but consider:


In this case, both c and b are known compile time constants.
 
arivu mathi
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thanks for your reply Peter....
can u throw some more light on what is the difference between c=b in both examples?
 
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5.2 Assignment Conversion may also help you.
 
Consider Paul's rocket mass heater.
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