Other Java Operators - JAVA Programming for Engineers - page 75

erandisasignednumber,sinceinsignedrepresentationsthehigh-order
bitencodesthesignofthenumber.Therefore,discardingthehigh-order
bitcanchangethesignofthevalue.ThiswouldbetrueforallJavainte-
gerdatatypes,exceptchar,whichisunsigned.Intheexamplein Figure
8-7 , theoriginalnumber,whichisnegative(high-bitset),ischangedintoa
positivevalue.Youmusttakethisintoaccountwhenleft-shiftingsigned
quantities.

Therearetworight-shiftoperatorsinJava,>and>>.Thesimple
right-shiftoperator(>)shiftstheleftoperandbythenumberofbitscon-
tainedintherightoperand,forexample:

int bitPattern = 127;
bitPattern = bitPattern > 1;

Intherightshift,thelow-orderbitisdiscardedandthehigh-orderbitis
duplicatedintoallthebitsthatwereabandonedbytheshift.Theresultis
extendingthesignbitintothenewoperand.Theactionofarightshiftby
1bitpositionisshownin Figure8-8 .

10101100

OPERAND BEFORE >> 1

HOB
reproduced

discarded

11010110

OPERAND AFTER >> 1

Figure8-8Actionofthe>Operator

Theunsignedrightshiftoperator(>>)issimilartotherightshift(>),
exceptthatinthe>>thevacatedpositionsontheleftoftheoperandare
filledwithzeros. Figure8-9 showsanunsignedrightshiftby1bitposi-
tion.

10101100

OPERAND BEFORE >>> 1

0shiftedin

discarded

01010110

OPERAND AFTER >>> 1

Figure 8-9 Action of the >> Operator