JAVA - Day2

Which of the following is immutable in Java?

• String

• StringBuffer

• StringBuilder

• Both B and C

What will be the output of the following code?
String s1 = "Hello";

String s2 = "Hello";

System.out.println(s1 == s2);

• true

• false

• Compilation error

• Runtime error

Which of the following is used to create a mutable string in Java?

• String

• StringBuffer

• StringBuilder

• Both B and C

Which method is used to get the length of a string?

• size()

• length()

• getSize()

• getLength()

Which of the following is thread-safe?

• String

• StringBuffer

• StringBuilder

• Both A and B

What will be the output of the following code?
String s = "Java";

s.concat("Programming");

System.out.println(s);

• JavaProgramming

• Java

• Compilation Error

• Runtime Error

Which of the following class provides fast and efficient string modification?

• String

• StringBuffer

• StringBuilder

• Both B and C

Which method is used to convert a String into an integer?

• Integer.parseInt()

• Integer.valueOf()

• toInt()

• Both A and B

What will be the output of the following code?
StringBuilder sb = new StringBuilder("Hello");

sb.append(" Java");

System.out.println(sb);

• Hello

• Java

• Hello Java

• Compilation Error

What is the purpose of the valueOf() method in wrapper classes?

• It converts a primitive type to a String

• It converts a String to a primitive type

• It returns the ASCII value of a character

• It removes spaces from a String