Java Reference
In-Depth Information
4.17
Suppose that
s1
and
s2
are two strings. Which of the following statements or
expressions are incorrect?
String s =
"Welcome to Java"
;
String s3 = s1 + s2;
String s3 = s1 - s2;
s1 == s2;
s1 >= s2;
s1.compareTo(s2);
int
i = s1.length();
char
c = s1(
0
);
char
c = s1.charAt(s1.length());
4.18
Show the output of the following statements (write a program to verify your results):
System.out.println(
"1"
+
1
);
System.out.println(
'1'
+
1
);
System.out.println(
"1"
+
1
+
1
);
System.out.println(
"1"
+ (
1
+
1
));
System.out.println(
'1'
+
1
+
1
);
4.19
Evaluate the following expressions (write a program to verify your results):
1
+
"Welcome "
+
1
+
1
1
+
"Welcome "
+ (
1
+
1
)
1
+
"Welcome "
+ (
'\u0001'
+
1
)
1
+
"Welcome "
+
'a'
+
1
4.20
Let
s1
be
" Welcome "
and
s2
be
" welcome "
. Write the code for the following
statements:
(a) Check whether
s1
is equal to
s2
and assign the result to a Boolean variable
isEqual
.
(b) Check whether
s1
is equal to
s2
,
ignoring case, and assign the result to a
Boolean variable
isEqual
.
(c) Compare
s1
with
s2
and assign the result to an
int
variable
x
.
(d) Compare
s1
with
s2
, ignoring case, and assign the result to an
int
variable
x
.
(e) Check whether
s1
has the prefix
AAA
and assign the result to a Boolean
variable
b
.
(f) Check whether
s1
has the suffix
AAA
and assign the result to a Boolean
variable
b
.
(g) Assign the length of
s1
to an
int
variable
x
.
(h) Assign the first character of
s1
to a
char
variable
x
.
(i) Create a new string
s3
that combines
s1
with
s2
.
(j) Create a substring of
s1
starting from index
1
.
(k) Create a substring of
s1
from index
1
to index
4
.
(l) Create a new string
s3
that converts
s1
to lowercase.
(m) Create a new string
s3
that converts
s1
to uppercase.
(n) Create a new string
s3
that trims whitespace characters on both ends of
s1
.
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