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
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