Expressions - The Java Language Specification - page 515

15.19. Shift Operators
The operators << (left shift), >> (signed right shift), and >>> (unsigned right shift) are called
the shift operators . The left-hand operand of a shift operator is the value to be shifted; the
right-hand operand specifies the shift distance.
ShiftExpression :
AdditiveExpression
ShiftExpression << AdditiveExpression
ShiftExpression >> AdditiveExpression
ShiftExpression >>> AdditiveExpression
The shift operators are syntactically left-associative (they group left-to-right).
Unary numeric promotion (§ 5.6.1 ) is performed on each operand separately. (Binary nu-
meric promotion (§ 5.6.2 ) is not performed on the operands.)
It is a compile-time error if the type of each of the operands of a shift operator, after unary
numeric promotion, is not a primitive integral type.
The type of the shift expression is the promoted type of the left-hand operand.
If the promoted type of the left-hand operand is int , only the five lowest-order bits of the
right-hand operand are used as the shift distance. It is as if the right-hand operand were sub-
jected to a bitwise logical AND operator & (§ 15.22.1 ) with the mask value 0x1f ( 0b11111 ).
The shift distance actually used is therefore always in the range 0 to 31 , inclusive.
If the promoted type of the left-hand operand is long , then only the six lowest-order bits
of the right-hand operand are used as the shift distance. It is as if the right-hand operand
were subjected to a bitwise logical AND operator & (§ 15.22.1 ) with the mask value 0x3f
( 0b111111 ). The shift distance actually used is therefore always in the range 0 to 63 , inclus-
ive.
At run time, shift operations are performed on the two's-complement integer representation
of the value of the left operand.
The value of n << s is n left-shifted s bit positions; this is equivalent (even if overflow oc-
curs) to multiplication by two to the power s .
The value of n >> s is n right-shifted s bit positions with sign-extension. The resulting value
is ? n / 2 s ?. For non-negative values of n , this is equivalent to truncating integer division,
as computed by the integer division operator / , by two to the power s .