Help debug -Type conversion program in java

[poojagupta1984]

What i know is:
In java, all byte and short data types are automatically promoted to int during a calculation. And, if you are casting a large data type like int to a byte then the int is reduced modulo the range of the short data type i.e byte (the range of byte is 256).

The program below has no compilation error. The output is incorrect for the first print statement..plea se explain why?

[CODE=Java]class TestByte
{
public static void main(String args[])
{
byte b = 50, c=50;
int i;
i=b*60;
b=(byte)(b*60);
c=(byte)(c*6);
System.out.prin tln(b); // should be 184
System.out.prin tln(c); // should be 44
System.out.prin tln(3000%256); //should be 184
System.out.prin tln(i); // should be 3000
}
}[/CODE]


Output:
-72
44
184
3000

[BigDaddyLH]

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[BigDaddyLH]

Why -72 instead of 184? Like long, int and short, type byte is signed. Its range of values is

-128 <= x <= 127

If you look at the bit pattern for 184:

10111000

The high bit is on. This means it's the 2's complement representation of a negative number, the negation of 256-184 or 72. Thus the result is -72.

[JosAH]

If the OP insists to see the value 184 use the bitmask operator & as in b&0xff
where b is the byte. Both operands are converted to ints and the bitwise and
operator chops off everything except the lowest eight bits which can represent
values in the range [0,255]

kind regards,

Jos