Decisions - Java Concepts - page 304

if (x < 0) s ++;
if (y > 0) s ++;

and

s = 0;
if (x < 0) s ++;
else if (y < 0) s ++;

΢΢ Exercise R5.10 Use de Morgan's law to simplify the following Boolean
expressions.

a. ! (x < 0 && y < 0)

b. !(x ! = 0 || y ! = 0)

c. !(country.equals("US") && ! state.equals("HI")

&& !state.equals("AK"))

d. !(x % 4 ! = 0 || ! (x % 100 == 0 && x % 400
== 0))

΢΢ Exercise R5.11 Make up another Java code example that shows the
dangling else problem, using the following statement: A student with a
GPA of at least 1.5, but less than 2, is on probation; with less than 1.5, the
student is failing.

΢ Exercise R5.12. Explain the difference between the == operator and the

equals method when comparing strings.

΢΢ Exercise R5.13 Explain the difference between the tests

r == s

and

r.equals(s)

where both r and s are of type Rectangle .

΢΢΢ Exercise R5.14 What is wrong with this test to see whether r is null ?
What happens when this code runs?