casting

[Naresh Gunda]

Hi,
can any one of u pls explain me how the casting takes place in the following code. Pls tell me how to find the output of the statements like..

class Test
{
public static void main(String args[])
{
byte b=(byte)150;
System.out.println(b);
}
}
Output: -106

Thanx in advance

[Renato Losio]

byte = 8 bits => 2^8

-106 == 150 mod 256

Windening conversion to char, calling public void println(char x)

See:

class Test
{
public static void main(String args[])
{
byte b=(byte)150;
byte c=(byte)-106;
System.out.println(b);
System.out.println(b==c);
}
}

[Naresh Gunda]

Thanq Renato Losio

[Barry Gaunt]

There is really no modulo stuff going on in casting.

150 = 128 + 16 + 4 + 2 = 0000 0000 0000 0000 0000 0000 1001 0110
Casting to a byte just takes the last (rightmost 8 bits) to get 1001 0110.

This is a negative number because of the highorder bit being set, so let's take the ones complement and add 1.

~1001 0110 is 0110 1001. Adding one, we get 0110 1010. This is 64 + 32 + 8 + 2 = 106.

So 150 (an int literal) cast to a byte gives -106.