Qn on abs () method

[cs singh]

class Q009 {
public static void main ( String args [ ] ) {
System . out . println ( ( Math . abs ( Integer . MIN _ VALUE ) ) );
}
};
 
Options :
 
a .  2147483648
b .  The code fails to compile
c .  -2147483648
d .  NegativeArraySizeException thrown at runtime    

why the ans is c here.?

[Keith Lynn]

The reason is because of the asymetry in the number of negative and positive integers that can be represented.

There are 2^31 negative whole numbers representable by an int, and 2^31-1 positive whole numbers representable by an int.

So there is one more negative whole number representable than there are positive whole numbers representable.

So Integer.MIN_VALUE has no positive counterpart.

Another way to look at it is the bit representation.

This is the bit representation of Integer.MIN_VALUE

10000000000000000000000000000000

In order to get the negative of a number we apply the complement operator to get the 1's complement and add 1 to get the 2's complement.

When we apply the complement operator we get

01111111111111111111111111111111

When we add 1 we get

10000000000000000000000000000000
[ March 14, 2006: Message edited by: Keith Lynn ]

[Bert Bates]

And for those of you studying for the 1.5 exam, don't panic! This topic isn't on the exam.

[cs singh]

Thanks a lot Keith for your valuable time...
got it now.