Java Questions & Answers – StringBuffer Methods

This section of our 1000+ Java MCQs focuses on StringBuffer class’s methods of Java Programming Language.

1. Which of these method of class StringBuffer is used to extract a substring from a String object?
a) substring()
b) Substring()
c) SubString()
d) None of the mentioned
View Answer

Answer: a
Explanation: None.

2. What will s2 contain after following lines of code?
StringBuffer s1 = “one”;
StringBuffer s2 = s1.append(“two”)
a) one
b) two
c) onetwo
d) twoone
View Answer

Answer: c
Explanation: Two strings can be concatenated by using append() method.

3. Which of these method of class StringBuffer is used to reverse sequence of characters?
a) reverse()
b) reverseall()
c) Reverse()
d) reverseAll()
View Answer

Answer: a
Explanation: reverse() method reverses all characters. It returns the reversed object on which it was called.

4. Which of these method of class StringBuffer is used to get the length of sequence of characters?
a) length()
b) capacity()
c) Length()
d) Capacity()
View Answer

Answer: c
Explanation: None.

5. Which of the following are incorrect form of StringBuffer class constructor?
a) StringBuffer()
b) StringBuffer(int size)
c) StringBuffer(String str)
d) StringBuffer(int size , String str)
View Answer

Answer: d
Explanation: None.

6. What is the output of this program?

  1.     class output {
  2.         public static void main(String args[])
  3.         { 
  4.              StringBuffer c = new StringBuffer("Hello");
  5.              System.out.println(c.length());
  6.         }
  7.     }

a) 4
b) 5
c) 6
d) 7
View Answer

Answer: b
Explanation: length() method is used to obtain length of StringBuffer object, length of “Hello” is 5.
Output:
$ javac output.java
$ java output
5

7. What is the output of this program?

  1.     class output {
  2.         public static void main(String args[])
  3.         { 
  4.              StringBuffer c = new StringBuffer("Hello");
  5.              StringBuffer c1 = new StringBuffer(" World");
  6.              c.append(c1);
  7.              System.out.println(c);
  8.         }
  9.     }

a) Hello
b) World
c) Helloworld
d) Hello World
View Answer

Answer: d
Explanation: append() method of class StringBuffer is used to concatenate the string representation to the end of invoking string.
Output:
$ javac output.java
$ java output
Hello World

8. What is the output of this program?

  1.     class output {
  2.         public static void main(String args[])
  3.         { 
  4.            StringBuffer s1 = new StringBuffer("Hello");
  5.            s1.setCharAt(1,x);
  6.            System.out.println(s1);
  7.         }
  8.     }

a) xello
b) xxxxx
c) Hxllo
d) Hexlo
View Answer

Answer: c
Explanation: None.
Output:
$ javac output.java
$ java output
Hxllo

9. What is the output of this program?

  1.     class output {
  2.         public static void main(String args[])
  3.         {
  4.            StringBuffer s1 = new StringBuffer("Hello World");
  5.            s1.insert(6 , "Good ");
  6.            System.out.println(s1);
  7.         }
  8.    }

a) HelloGoodWorld
b) HellGoodoWorld
c) HellGood oWorld
d) Hello Good World
View Answer

Answer: d
Explanation: The insert() method inserts one string into another. It is overloaded to accept values of all simple types, plus String and Objects. Sting is inserted into invoking object at specified position. “Good ” is inserted in “Hello World” T index 6 giving “Hello Good World”.
output:
$ javac output.java
$ java output
Hello Good World

10. What is the output of this program?

  1.     class output {
  2.         public static void main(String args[])
  3.         { 
  4.            StringBuffer s1 = new StringBuffer("Hello");
  5.            s1.deleteCharAt(1);
  6.            System.out.println(s1);
  7.         }
  8.     }

a) Hell
b) ello
c) Hllo
d) Helo
View Answer

Answer: c
Explanation: None.
Output:
$ javac output.java
$ java output
Hllo

Sanfoundry Global Education & Learning Series – Java Programming Language.

About

Manish Bhojasia, a technology veteran with 17+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer and SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage & Cluster Administration, Advanced C Programming, SAN Storage Technologies, SCSI Internals and Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him below.


Sanfoundry Training Center of Excellence (CoE)

Manish Bhojasia, a technology veteran with 17+ years @ Cisco & Wipro, is Founder and CTO at Sanfoundry. He is Linux Kernel Developer and SAN Architect and is passionate about competency developments in these areas. He lives in Bangalore and delivers focused training sessions to IT professionals in Linux Kernel, Linux Debugging, Linux Device Drivers, Linux Networking, Linux Storage & Cluster Administration, Advanced C Programming, SAN Storage Technologies, SCSI Internals and Storage Protocols such as iSCSI & Fiber Channel. Stay connected with him below.







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