Math.abs Q

[Nitin Bhagwat]

Why abs of Long.MIN_VALUE gives negative result?
Thank you in advance!

 
public class Test{    
   public static void main(String args[])
   {
     System.out.println(Math.abs(Byte.MIN_VALUE));
     System.out.println(Math.abs(Long.MIN_VALUE));
     System.out.println(Math.abs(Double.MIN_VALUE));
   }
}

[PNS Subramanian]

Incidentally
Math.abs(Long.MIN_VALUE)+1 gives a negative value and
Math.abs(Long.MIN_VALUE)-1 gives a positive value.

[Mike Gershman]

In 2's complement arithmetic, the smallest negative number of a given size is one larger in magnitude than the largest positive number of the same size. For example, a long runs from -9223372036854775808 to 9223372036854775807. If you take the absolute value of Long.MIN_VALUE, there is no correct answer representable as a Long.


From the Java 5 API for Math.abs():

Note that if the argument is equal to the value of Long.MIN_VALUE, the most negative representable long value, the result is that same value, which is negative.

[ December 04, 2004: Message edited by: Mike Gershman ]