Large Integer Computing - Introduction to Cryptography with Java Applets - page 57

then the following call

BigInteger c = a.or(b);

leaves with the value 1011011 base 2 .

This method returns a negative number iff either

c

this or val is negative.

• public BigInteger xor(BigInteger val)
This method returns a BigInteger whose value is ( this ^ val).

E XAMPLE . This method performs a bitwise exclusive OR on the two operands. So if a and
b are as defined previously; that is,

a = 1001011 base 2

b = 1011010 base 2

then the following call

BigInteger c = a.xor(b);

leaves with the value 0010001 base 2 .

This method returns a negative number iff exactly one of

c

this and val are negative.

• public BigInteger not()
This method returns a BigInteger whose value is this with each bit flipped. It returns a
negative value iff this is nonnegative.

E XAMPLE .

Thus, if we are using b as defined earlier; that is,

b = 1011010 base 2 ,

then the following call

BigInteger c = b.not();

leaves c with the value 0100101 base 2 .

• public BigInteger andNot(BigInteger val)
This method is equivalent to and(val.not()), and is provided as a convenience for mask-
ing operations. This method returns a negative number iff

this is negative and val is posi-

tive.

• public boolean testBit(int n) throws ArithmeticException
This method returns true iff the designated bit is set, and throws an ArithmeticException

if n < 0.