This section of our 1000+ Java MCQs focuses on searching and modifying a string of Java Programming Language.
1. Which of this method of class String is used to extract a substring from a String object?
a) substring()
b) Substring()
c) SubString()
d) None of the mentioned
View Answer
Explanation: None.
2. What will s2 contain after following lines of Java code?
String s1 = "one"; String s2 = s1.concat("two")
a) one
b) two
c) onetwo
d) twoone
View Answer
Explanation: Two strings can be concatenated by using concat() method.
3. Which of these method of class String is used to remove leading and trailing whitespaces?
a) startsWith()
b) trim()
c) Trim()
d) doTrim()
View Answer
Explanation: None.
4. What is the value returned by function compareTo() if the invoking string is greater than the string compared?
a) zero
b) value less than zero
c) value greater than zero
d) none of the mentioned
View Answer
Explanation:
if (s1 == s2) then 0, if(s1 > s2) > 0, if (s1 < s2) then < 0.
5. Which of the following statement is correct?
a) replace() method replaces all occurrences of one character in invoking string with another character
b) replace() method replaces only first occurrences of a character in invoking string with another character
c) replace() method replaces all the characters in invoking string with another character
d) replace() replace() method replaces last occurrence of a character in invoking string with another character
View Answer
Explanation: replace() method replaces all occurrences of one character in invoking string with another character.
6. What will be the output of the following Java program?
class output
{
public static void main(String args[])
{
String c = " Hello World ";
String s = c.trim();
System.out.println("\""+s+"\"");
}
}
a) “”Hello World””
b) “”Hello World”
c) “Hello World”
d) Hello world
View Answer
Explanation: trim() method is used to remove leading and trailing whitespaces in a string.
Output:
$ javac output.java $ java output "Hello World"
7. What will be the output of the following Java program?
class output
{
public static void main(String args[])
{
String s1 = "one";
String s2 = s1 + " two";
System.out.println(s2);
}
}
a) one
b) two
c) one two
d) compilation error
View Answer
Explanation: None.
Output:
$ javac output.java
$ java output
one two
8. What will be the output of the following Java program?
class output
{
public static void main(String args[])
{
String s1 = "Hello";
String s2 = s1.replace('l','w');
System.out.println(s2);
}
}
a) hello
b) helwo
c) hewlo
d) hewwo
View Answer
Explanation: replace() method replaces all occurrences of one character in invoking string with another character. s1.replace(‘l’,’w’) replaces every occurrence of ‘l’ in hello by ‘w’, giving hewwo.
Output:
$ javac output.java
$ java output
hewwo
9. What will be the output of the following Java program?
class output
{
public static void main(String args[])
{
String s1 = "Hello World";
String s2 = s1.substring(0 , 4);
System.out.println(s2);
}
}
a) Hell
b) Hello
c) Worl
d) World
View Answer
Explanation: substring(0,4) returns the character from 0 th position to 3 rd position.
output:
$ javac output.java
$ java output
Hell
10. What will be the output of the following Java program?
class output
{
public static void main(String args[])
{ String s = "Hello World";
int i = s.indexOf('o');
int j = s.lastIndexOf('l');
System.out.print(i + " " + j);
}
}
a) 4 8
b) 5 9
c) 4 9
d) 5 8
View Answer
Explanation: indexOf() method returns the index of first occurrence of the character where as lastIndexOf() returns the index of last occurrence of the character.
output:
$ javac output.java $ java output 4 9
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