Yes. Sometimes boolean variables like reject are used
to record a decision that might be used in several places in the program.
The NOT operator has high precedence. It is done before arithmetic and relational operators unless you use parentheses. Examine the following:
!speed > 2000 && memory > 512 --+--- illegal: can't use ! on an arithmetic variable
Since ! has high precedence,
the above says to apply it to
speed.
This which won't work, because speed is an integer and
! applies only to boolean values.
When parentheses are used
!(speed > 2000 && memory > 512)
the ! is the last operation done, and is applied to the boolean value of the
expression inside parentheses.
Expressions that involve a NOT operator are often hard to read. A confusing expression can be sometimes be rewritten to eliminate the NOT.
Look at the original fragment:
if ( !( speed > 2000 && memory > 512 ) )
System.out.println("Reject this computer");
else
System.out.println("Acceptable computer");
Does the following do the same thing?
if ( speed <= 2000 || memory <= 512 )
System.out.println("Reject this computer");
else
System.out.println("Acceptable computer");
Use some example values for speed
and memory and figure out what each fragment does.
