Java MCQ

Q51. What is the purpose of the 'instance initializer' block in Java?

a) It is used to initialize instance variables

b) It is used to define methods

c) It is used to define constants

d) It is used to create instances of a class

a) It is used to initialize instance variables

Q52. What is the difference between 'final' and 'finally' in Java?

a) 'final' is used to prevent inheritance, while 'finally' is used to define a block of code that is always executed

b) 'final' is used to define a constant, while 'finally' is used to specify the default case in a switch statement

c) 'final' is used to indicate that a variable cannot be modified, while 'finally' is used to define a block of code that is always executed

d) 'final' is used to indicate that a method cannot be overridden, while 'finally' is used to define a block of code that is always executed after a try-catch block

c) 'final' is used to indicate that a variable cannot be modified, while 'finally' is used to define a block of code that is always executed

Q53. Which of the following is true about the 'break' statement in Java?

a) It is used to terminate the program

b) It is used to skip the current iteration of a loop

c) It is used to exit a switch statement

d) It is used to create a loop that repeats indefinitely

c) It is used to exit a switch statement

Q54. What is the purpose of the 'Math' class in Java?

a) It is used to perform mathematical calculations

b) It is used to define constants

c) It is used to handle exceptions

d) It is used to create instances of classes

a) It is used to perform mathematical calculations

Q55. What is the purpose of the 'Comparator' interface in Java?

a) It is used to compare objects for equality

b) It is used to sort objects based on their natural order

c) It is used to compare objects based on a specified criteria

d) It is used to convert objects to strings

c) It is used to compare objects based on a specified criteria

Q56. Which Java method is called automatically when an object is garbage collected?

a) finalize()

b) delete()

c) collect()

d) dispose()

a) finalize()

Q57. What is a constructor chaining in Java?

a) It is a mechanism to call a static constructor

b) It is a mechanism to call methods in a constructor

c) It is a mechanism to call one constructor from another constructor within the same class or in the superclass

d) It is a mechanism to call a constructor of a different class

c) It is a mechanism to call one constructor from another constructor within the same class or in the superclass

Q58. Which of the following is true about the 'this' keyword in Java?

a) It is used to refer to the superclass

b) It is used to refer to the current instance of the class

c) It is used to declare instance variables

d) It is used to indicate the end of a method

b) It is used to refer to the current instance of the class

Q59. What is the purpose of the 'throws' clause in a method signature in Java?

a) It is used to indicate that a method is throwing an exception

b) It is used to indicate that a method is catching an exception

c) It is used to indicate that a method is asynchronous

d) It is used to indicate that a method is abstract

a) It is used to indicate that a method is throwing an exception

Q60. What is the purpose of the 'do-while' loop in Java?

a) It is used to create an infinite loop

b) It is used to iterate over a range of values

c) It is used to repeat a block of code while a condition is true

d) It is used to execute a block of code at least once, regardless of the condition

d) It is used to execute a block of code at least once, regardless of the condition

Q61. What is a thread in Java?

a) A method

b) A type of data structure

c) A lightweight process that runs concurrently with other threads

d) A special type of loop

c) A lightweight process that runs concurrently with other threads

Q62. What is the purpose of the 'null' keyword in Java?

a) It is used to indicate that a variable has no value

b) It is used to indicate that a variable is constant

c) It is used to indicate that a variable is immutable

d) It is used to indicate that a variable is synchronized

a) It is used to indicate that a variable has no value

Q63. What is the purpose of the 'import' statement in Java?

a) It is used to include a package in the class

b) It is used to import a class into another class

c) It is used to include predefined methods

d) It is used to import data from external files

b) It is used to import a class into another class

Q64. What is the purpose of the 'volatile' keyword in Java?

a) It is used to indicate that a variable is immutable

b) It is used to indicate that a variable is synchronized

c) It is used to indicate that a variable can be modified by multiple threads

d) It is used to indicate that a variable has a fixed value

c) It is used to indicate that a variable can be modified by multiple threads

Q65. What is the purpose of the 'try-catch' block in Java?

a) It is used to define a block of code that is always executed

b) It is used to indicate that a method is throwing an exception

c) It is used to handle exceptions and prevent the program from crashing

d) It is used to declare variables in a method

c) It is used to handle exceptions and prevent the program from crashing

Q66. What is the purpose of the 'continue' statement in Java?

a) It terminates the loop

b) It skips the current iteration of the loop and continues with the next iteration

c) It exits the loop

d) It reverses the loop's direction

b) It skips the current iteration of the loop and continues with the next iteration

Q67. What is the purpose of the 'static' keyword when applied to methods in Java?

a) It indicates that a method is static and cannot be overridden

b) It indicates that a method can be called on a class, not on instances of the class

c) It indicates that a method is asynchronous

d) It indicates that a method is abstract and must be overridden in subclasses

b) It indicates that a method can be called on a class, not on instances of the class

Q68. What is the purpose of the 'clone' method in Java?

a) It is used to create a new instance of a class

b) It is used to copy an object to another object

c) It is used to convert an object to a string

d) It is used to delete an object from memory

b) It is used to copy an object to another object

Q69. What is the purpose of the 'break' statement in Java?

a) It terminates the loop

b) It skips the current iteration of the loop and continues with the next iteration

c) It exits the loop

d) It reverses the loop's direction

c) It exits the loop

Q70. What is the purpose of the 'interface' keyword in Java?

a) It is used to create a new instance of a class

b) It is used to define a type of exception

c) It is used to indicate that a class cannot be subclassed

d) It is used to define a contract for implementing methods in a class

d) It is used to define a contract for implementing methods in a class

Q71. What is a wrapper class in Java?

a) A class that wraps another class

b) A class that defines methods

c) A class that encapsulates primitive data types into objects

d) A class that is used to create threads

c) A class that encapsulates primitive data types into objects

Q72. What is the purpose of the 'throws' clause in a method signature in Java?

a) It is used to indicate that a method is throwing an exception

b) It is used to indicate that a method is catching an exception

c) It is used to indicate that a method is asynchronous

d) It is used to indicate that a method is abstract