Java Reference
In-Depth Information
9.5
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 blank spaces on both ends of
s1
.
o. Replace all occurrences of the character
e
with
E
in
s1
and assign the new string to
s3
.
p. Split
Welcome to Java and HTML
into an array
tokens
delimited by a space.
q. Assign the index of the first occurrence of the character
e
in
s1
to an
int
variable
x
.
r.
Assign the index of the last occurrence of the string
abc
in
s1
to an
int
variable
x
.
9.6
Does any method in the
String
class change the contents of the string?
9.7
Suppose string
s
is created using
new String()
; what is
s.length()
?
9.8
How do you convert a
char
, an array of characters, or a number to a string?
9.9
Why does the following code cause a
NullPointerException
?
1
public class
Test {
2
private
String text;
3
4
public
Test(String s) {
5
6 }
7
8
public static void
main(String[] args) {
9 Test test =
new
Test(
"ABC"
);
10 System.out.println(test.text.toLowerCase());
11 }
12 }
String text = s;
9.10
What is wrong in the following program?
1
public class
Test {
2 String text;
3