The correct answer has been posted more than once, but not from an authoritative source.
This is from the JLS §15.19 Shift Operators:
The shift operators include left shift <<, signed right shift >>, and unsigned right shift >>>; they are syntactically left-associative (they group left-to-right). The left-hand operand of a shift operator is the value to be shifted; the right-hand operand specifies the shift distance.
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The value of n>>s is n right-shifted s bit positions with sign-extension. The resulting value is ⌊n/2s⌋. For nonnegative values of n, this is equivalent to truncating integer division, as computed by the integer division operator /, by two to the power s.
The value of n>>>s is n right-shifted s bit positions with zero-extension. If n is positive, then the result is the same as that of n>>s; if n is negative, the result is equal to that of the expression (n>>s)+(2<<~s) if the type of the left-hand operand is int, and to the result of the expression (n>>s)+(2L<<~s) if the type of the left-hand operand is long. The added term (2<<~s) or (2L<<~s) cancels out the propagated sign bit. (Note that, because of the implicit masking of the right-hand operand of a shift operator, ~s as a shift distance is equivalent to 31-s when shifting an int value and to 63-s when shifting a long value.)
