Java
provides bit wise shift operation only on integral types (int, long, possibly
short and byte or char).
There
are 3 types of bit wise shift operators.
1) >> (Signed right shift operator)
It
will shift the bit pattern of the first argument to the right by the number of
positions mentioned in the second argument. It fills in positions on the left with zeros. It
keeps the sign of the argument unchanged.
Example
|
Meaning In Binary format
|
Result
|
2
>>1
|
10 should be shifted to right by 1 position
(keep the sign unchanged)
|
1
|
-2
>> 1
|
10 should be shifted to right by 1 position
(keep the sign unchanged)
|
-1
|
Byte
representation (8 bytes)
2
>> 1
|
1
|
||||||||||||||||
|
|
-2
>> 1
|
-1
|
||||||||||||||||
|
|
Red color to indicate sign
This
operator gives the value which is equal to the integer division by 2^n where n
is the number of positions.
2) << (Signed left shift operator)
It
will shift the bit pattern of the first argument to the left by the number of
positions mentioned in the second argument. It fills in positions on the right
with zeros.
It keeps the sign of the argument unchanged.
Example
|
Meaning In Binary format
|
Result
|
2
<< 1
|
10 should be shifted to left by 1 position
(keep the sign unchanged)
|
4
|
-2
<< 1
|
10 should be shifted to left by 1 position
(keep the sign unchanged)
|
-
4
|
Byte
representation (8 bytes)
2
<< 1
|
4
|
||||||||||||||||
|
|
-2
<< 1
|
-4
|
||||||||||||||||
|
|
Red color to indicate sign
This
operator gives the value which is equal to the integer multiplication by 2^n
where n is the number of positions.
3) >>>
(Unsigned right shift operator)
It
shifts bit pattern of the first argument to the right by the number of
positions mentioned in the second argument without caring what the original
sign was. It fills in positions on the left with zeros.
Byte
representation (8 bytes)
2
>>> 1
|
1
|
||||||||||||||||
|
|
-2
>>> 1
|
65
|
||||||||||||||||
|
|
Red color to indicate sign
This
operator works differently based on the sign of the first argument. It does not
keep the sign of the argument. (Which means it may change) .In case of Positive
numbers it works just like a signed right shift operator. For negative numbers
this operator produces a positive value.
Java code to test the shift operators is
below. (Please note that the code below uses 32 bytes since integer is used)
public class
BitOperatorsExample {
public static void main(String[]
args) {
int i = 2;
int negi = -2;
int
leftShiftPositive = i << 1; // 20
int
leftShiftNegative = negi << 1; // -4
int
rightShiftPositive = i >> 1; // 2
int
rightShiftNegative = negi >> 1; // -1
int
UnsignedRightShiftPositive = i >>> 1; //1
int
UnsignedRightShiftNegative = negi
>>> 1; //2147483647
System.out.println(Math.pow(2,
31));
System.out.println("leftShiftPositive
:"+ leftShiftPositive);
System.out.println("leftShiftNegative
:"+ leftShiftNegative);
System.out.println("rightShiftPositive
:"+ rightShiftPositive);
System.out.println("rightShiftNegative
:"+ rightShiftNegative);
System.out.println("UnsignedRightShiftPositive
:"+ UnsignedRightShiftPositive);
System.out.println("UnsignedRightShiftNegative
:"+ UnsignedRightShiftNegative);
}
}
