Java Reference
In-Depth Information
3.21
Assume that
x
and
y
are
int
type. Which of the following are legal Java expressions?
x > y >
0
x = y && y
x /= y
x or y
x and y
(x !=
0
) || (x =
0
)
3.22
Suppose that
x
is
1
. What is
x
after the evaluation of the following expression?
a. (x >=
1
) && (x++ >
1
)
b. (x >
1
) && (x++ >
1
)
3.23
What is the value of the expression
ch >= 'A' && ch <= 'Z'
if
ch
is
'A'
,
'p'
,
'E'
, or
'5'
?
3.24
Suppose, when you run the program, you enter input
2 3 6
from the console. What
is the output?
public class
Test {
public static void
main(String[] args) {
java.util.Scanner input =
new
java.util.Scanner(System.in);
double
x = input.nextDouble();
double
y = input.nextDouble();
double
z = input.nextDouble();
System.out.println(
"(x < y && y < z) is "
+ (x < y && y < z));
System.out.println(
"(x < y || y < z) is "
+ (x < y || y < z));
System.out.println(
"!(x < y) is "
+ !(x < y));
System.out.println(
"(x + y < z) is "
+ (x + y < z));
System.out.println(
"(x + y < z) is "
+ (x + y < z));
}
}
3.25
Write a Boolean expression that evaluates
true
if
age
is greater than
13
and less
than
18
.
3.26
Write a Boolean expression that evaluates
true
if
weight
is greater than
50
pounds
or height is greater than
60
inches.
3.27
Write a Boolean expression that evaluates
true
if
weight
is greater than
50
pounds
and height is greater than
60
inches.
3.28
Write a Boolean expression that evaluates
true
if either
weight
is greater than
50
pounds or height is greater than
60
inches, but not both.
A year is a
leap year
if it is divisible by
4
but not by
100
, or if it is divisible by
400
.
You can use the following Boolean expressions to check whether a year is a leap year:
Key
Point
// A leap year is divisible by 4
boolean
isLeapYear = (year %
4
==
0
);
// A leap year is divisible by 4 but not by 100
isLeapYear = isLeapYear && (year %
100
!=
0
);
// A leap year is divisible by 4 but not by 100 or divisible by 400
isLeapYear = isLeapYear || (year %
400
==
0
);
Or you can combine all these expressions into one like this:
isLeapYear = (year %
4
==
0
&& year %
100
!=
0
) || (year %
400
==
0
);