Bitwise shift operators. Signed and unsigned

bit-shift, java, scjp

Solution

">>" is signed because it keeps the sign. It uses the most left digit in binary representation of a number as a filler. For example:

    | this value is used as a filler 
    11011011 
 >> 11101101  

    01010010
 >> 00101001

">>>" is unsigned version of this operator. It always use zero as a filler:

    11011011 
>>> 01101101  

    01010010
>>> 00101001

In binary representation the most left digit determines sign of the number. So, if it's '1' then we have negative value and if it's '0' - then our number is positive. That's why using the most left digit as a filler allows to keep sign permanent.

Problem

I'm practising for the SCJP exam using cram notes from the Internet. According to my notes the `>>` operator is supposed to be signed right shift, with the sign bit being brought in from the left. While the left shift operator `<<` is supposed to preserve the sign bit. Playing around however, I'm able to shift the sign with the `<<` operator (f.e. `Integer.MAX_VALUE << 1` evaluates to `-2`, while I'm never able to shift the sign with the `>>` operator. I must be misunderstanding something here, but what?

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