# Java Tutorials : Java Operators Explained

**3. Shift operators - <<, >>, >>>**

- << Performs a signed left shift. 0 bits are brought in from the right. Sign bit (MSB) is preserved. Value becomes old value * 2 ^ x where x is no of bits shifted.
- >> Performs a signed right shift. Sign bit is brought in from the left. (0 if positive, 1 if negative. Value becomes old value / 2 ^ x where x is no of bits shifted. Also called arithmetic right shift.
- >>> Performs an unsigned logical right shift. 0 bits are brought in from the left. This operator exists since Java doesn't provide an unsigned data type (except char). >>> Changes the sign of a negative number to be positive. So don't use it with negative numbers, if you want to preserve the sign. Also don't use it with types smaller than int. (Since types smaller than int are promoted to an int before any shift operation and the result is cast down again, so the end result is unpredictable.)
- Shift operators can be applied to only integral types.
- -1 >> 1 is -1, not 0. This differs from simple division by 2. We can think of it as shift operation rounding down.
- 1 << 31 will become the minimum value that an int can represent. (Value becomes negative, after this operation, if you do a signed right shift sign bit is brought in from the left and the value remains negative.)
- Negative numbers are represented in two's complement notation. (Take one's complement and add 1 to get two's complement)
- Shift operators never shift more than the number of bits the type of result can have. (i.e. int 32, long 64) RHS operand is reduced to RHS % x where x is no of bits in type of result.

**4. Comparison operators :**all return
Boolean type.

4.1 Ordinal comparisons - <, <=, > , >=

- Only operate on numeric types. Test the relative value of the numeric operands.
- Arithmetic promotions apply. char can be compared to float.

4.2 Object type comparison - instanceof