Problem with bits operation

Question

Hi
I have the next code that is throwing the
recorreBits.java:8: possible loss of precision
found   : int
required: byte
  byte c =        a & b;
                         ^
1 errorand the code is
public class recorreBits {
     public static void main(String args[])
     byte a = 0x20;
     byte b = 0x10;
     byte c = a & b;
     System.out.println(c);
          }I'm using byte don't know whyt it found's a int. Thanks
Edited by: Ikim on Oct 6, 2009 1:14 PM

Answer 1

[JLS 15.22.1 Integer Bitwise Operators|http://java.sun.com/docs/books/jls/third_edition/html/expressions.html#15.22.1] says:
When both operands of an operator &, ^, or | are of a type that is convertible (§5.1.8) to a primitive integral type, binary numeric promotion is first performed on the operands (§5.6.2). The type of the bitwise operator expression is the promoted type of the operands.
So, since byte is a primitive integral type, binary numeric promotion occurs, and both are converted to int, and the result is then int. You can't assign an int value to a byte variable, unless it's a compile-time constant, so you have to cast.
byte c = (byte)(a & b);Edited by: jverd on Oct 6, 2009 1:19 PM