August 2, 2024

1.What is a StringBuffer?

a)class

b)method

c)constructor

Ans class

2. StringBuffer is mutable.

a)True

b) False

Ans True

3.StringBuffer is not synchronized.

a)True

b) False

And False

4. String buffer creates an empty constructor with an initial capacity.

a)12

b)20

c)16

Ans 16

5. String buffer reverse() method.

a) It is used to return the current capacity.

b) It is used to reverse the string.

Ans It is used to reverse the string.

6. What is the return type of String buffer charAt(int index)?

a) char

b) int

c) StringBuffer

Ans char

7. Non-Synchronized means not thread-safe.

a)True

b)False

Ans True

8. Which method will be used in StringBuffer to add Jacob after Carlson?

String fname=“carlson mathew”;

a)insert

b)delete

c)reverse

Ans insert

9. What does ‘+’ mean in the below String?

String a1=a+” mathew”;

a)concat

b)reverse

Ans concat

10. StringBuffer(String str) is a parameterized constructor.

a)True

b)False

Ans True

11. StringBuffer was introduced with the initial release of Java.

a)1.0

b)1.5

Ans 1.0

12. StringBuffer uses a special memory string pool.

a)True

b) False

Ans False

13. StringBuffer we add, remove, and insert characters.

a) True

b)False

Ans True

14. StringBuffer uses which memory?

a)Heap

b) String pool

Ans Heap

15.StringBuffer name=new StringBuffer(“carlson mathew”);

System.out.println(name.length());

a)15

b)14

Ans 14

16. StringBuilder is mutable.

a)True

b) False

Ans True

17. StringBuilder is not synchronized.

a)True

b) False

Ans True

18. StringBuilder and StringBuffer methods are same?

a)True

b) False

Ans True

19. StringBuilder uses which memory?

a)Heap

b) String pool

Ans Heap

20. StringBuilder was introduced with the initial release of Java.

a)1.0

b)1.5

Ans 1.5

21. StringBuilder is not thread-safe hence faster than String Buffer.

a)True

b) False

Ans True

22. Which class reverse() method belongs to?

a) StringBuffer

b)String Builder

c) String

d) Both a) and b)

Ans Both a) and b)

23.The method of StringBuffer and StringBuilder class which return the current capacity is called as?

a)ensureCapacity(int minimumCapacity)

b)capacity()

Ans capacity()

24. What is StringBuilder() called?

a)constructor

b)class

c)interface

Ans constructor

25. What is the return type of ensureCapacity() method of StringBuilder class?

a)void

b)int

c)String

Ans void

26. Which of the following is not synchronized?

a)StringBuffer

b)StringBuilder

Ans StringBuilder

27. What is the default capacity of the StringBuilder?

a)10

b)16

c)12

Ans 16

28. What will be the output of the following Java program?

				
					class Hello 
{ public static void main(String args[]) 
{ StringBuilder c = new StringBuilder("Hello");  c.delete(0,2); 
System.out.println(c); } }

a)he

b)hel

c)lo

d)llo

Ans llo

29. What is the output of the following code snippet?

				
					public class Alex  
{    public static void main(String[] args)  
{ String str = "Java";   str.concat(" Programming");   
System.out.println(str);   } }

a)Java

b)Java Programming

Ans Java

30. Which method is used to delete the string from the specified startIndex and endIndex?

a)delete(int startIndex,int endIndex)

b)substring(intbeginIndex, intendIndex)

Ans delete(int startIndex,int endIndex)

Read blog on StringBuffer and methods