(cast)ing rules

[Leroy J Brown]

So,
I'm reading about casts which is a subject that I find odd and was wondering if anyone knew of a resource where I could find say a table or explicit list of what primitives require an explicit cast statement when their operated on ie

byte b1 = 1, b2 = 2;
byte b3 = b1 + b2; // no good

Ideally I'd like to print the sucker out and stick it on my wall next to my Precedence of Operators table.
Any ideas?
[ June 17, 2008: Message edited by: Tristan Rouse ]

[Ashish Hareet]

Tristan,

The simplest rule to follow with primitive casting is that the result of an arithmetic operation(excluding ++ & -- operators) will atleast be of type int or of the larger primitive type used in the operation.

For more you can read the following in the JLS
* http://java.sun.com/docs/books/jls/third_edition/html/conversions.html#5.1.2
* http://java.sun.com/docs/books/jls/third_edition/html/conversions.html#5.1.3

HTH
Ashish Hareet

[Leroy J Brown]

Thanks friend

[Yoogesh Patil]

class Casting {
public static void main (String [] args){
long ln = 130L;
byte by = (byte) ln;
System.out.println ("\n Casting value is: "+by);
}
}

The answer is: -126
My question is: how does it works conceptually?
means how does jvm handles this code if long is greater that 127 (byte value limit)

[Campbell Ritchie]

Welcome to JavaRanch, Yoogesh Patil.

Please don't ask new questions on somebody else's thread.

If you write out the bits for 130 in 16 bits, which are the same as a long only with fewer 0s, you get
0000 0000 1000 0010.
When you cast to a byte you lose all but the rightmost 8 bits, leaving
1000 0010.
In two's complement that is -126.

If you want any more information please start a new thread.
[ June 25, 2008: Message edited by: Campbell Ritchie ]