1. Bits and Bytes Hex Digit Bit Pattern 0000 1 0001 2 0010 3 0011 4 0100
0000 1
0001 2
0010 3
0011 4
0100 5
0101 6
0110 7
0111 8
1000 9
1001 a
1010 b
1011 c
1100 d
1101 e
1110 f
1111
One bit stores either 0 or 1.
One byte is a sequence of 8 bits.
One Java int is a sequence of 4 bytes or 32 bits.
Each half (nibble) of a byte can be
represented by a single hexadecimal digit.
To express Java data (int) in hexadecimal use…
0xHHHHHHHH
where "H" is one hex digit
Examples
0x00ffffff
0xff00ffff
0xab

2. Bitwise Operations Hex Digit Bit Pattern 0000 1 0001 2 0010 3 0011 4
0000 1
0001 2
0010 3
0011 4
0100 5
0101 6
0110 7
0111 8
1000 9
1001 a
1010 b
1011 c
1100 d
1101 e
1110 f
1111
& means bitwise AND
Each bit is treated as follows:
0 & 0  0
0 & 1  0
1 & 0  0
1 & 1  1
| means bitwise OR
Each bit is treated as follows:
0 | 0  0
0 | 1  1
1 | 0  1
1 | 1  1
Example
int bits = 0xabcdefab;
bits = bits & 0xff00ffff;
bits = 0xabcdefab;
bits = bots | 0xff00ffff;

3. More Bitwise Operations
Hex Digit
Bit Pattern
0000 1
0001 2
0010 3
0011 4
0100 5
0101 6
0110 7
0111 8
1000 9
1001 a
1010 b
1011 c
1100 d
1101 e
1110 f
1111
<<< n means shift left by n (n is an integer)
>>> n means shift right by n (n is an integer)
Example
int bits = 0x00abcdefab;
bits = bits >>> 8;
bits = bits <<< 8;
bits = 0xff00ffff;
bits = bits >>> 16;
Two more things…
1) A cast to byte returns the rightmost byte
of int, long or short data.
2) Treating a byte as an int, short or long
sign extends.
Example
int bits = 0x00abcdefab;
byte oneByte = (byte)bits;
bits = oneByte;