Java Reference
In-Depth Information
Tip
Often new programmers write the code that assigns a test condition to a
boolean
variable like the code in (a):
assign
boolean
variable
if
(number %
2
==
0
)
even =
true
;
else
even =
false
;
boolean
even
= number %
2
==
0
;
Equivalent
This is shorter
(a)
(b)
The code can be simplified by assigning the test value directly to the variable, as shown
in (b).
✓
✓
Check
Point
3.11
Which of the following statements are equivalent? Which ones are correctly indented?
if
(i >
0
)
if
(j >
0
)
x =
0
;
else
if
(k >
0
) y =
0
;
else
z =
0
;
if
(i >
0
) {
if
(j >
0
)
x =
0
;
else
if (k >
0
)
y =
0
;
if
(i >
0
)
if
(j >
0
)
x =
0
;
else if
(k >
0
)
y =
0
;
else
z =
0
;
if
(i >
0
)
if
(j >
0
)
x =
0
;
else if
(k >
0
)
y =
0
;
}
else
z =
0
;
else
z =
0
;
(a)
(b)
(c)
(d)
3.12
Rewrite the following statement using a Boolean expression:
if
(count %
10
==
0
)
newLine =
true
;
else
newLine =
false
;
3.13
Are the following statements correct? Which one is better?
if
(age <
16
)
System.out.println
(
"Cannot get a driver's license"
);
if
(age >=
16
)
System.out.println
(
"Can get a driver's license"
);
if
(age <
16
)
System.out.println
(
"Cannot get a driver's license"
);
else
System.out.println
(
"Can get a driver's license"
);
(a)
(b)
3.14
What is the output of the following code if
number
is
14
,
15
, and
30
?
if
(number % 2 ==
0
)
System.out.println
(number +
" is even"
);
if
(number % 5 ==
0
)
System.out.println
(number +
" is multiple of 5"
);
if
(number % 2 ==
0
)
System.out.println
(number +
" is even"
);
else if
(number % 5 ==
0
)
System.out.println
(number +
" is multiple of 5"
);
(a)
(b)
