Objects and Collections Questions with Answers | Page 3

Java Objects and Collections programming questions and answers are essential for mastering object-oriented design and data structure handling. These questions often appear in coding interviews by Infosys, TCS, and Accenture. The topic covers object creation, reference handling, garbage collection, and the use of Java Collection Framework classes like List, Set, and Map. Understanding how to manage and iterate over collections efficiently helps in building optimized programs. Practicing programming questions and answers in this area enhances both logic and coding speed—crucial skills for clearing technical interview rounds and online assessments.

Showing 10 of 38 questions

Per page:

Q21

Which wrapper class represents integer values?

A Float
B Integer
C Double
D String

Answer: Option B

Explanation: Integer is the wrapper class for int.

Q22

Which collection class maintains insertion order?

A HashSet
B TreeSet
C LinkedHashSet
D PriorityQueue

Answer: Option C

Explanation: LinkedHashSet preserves insertion order.

Q23

Which method adds an element to an ArrayList?

A insert()
B put()
C add()
D push()

Answer: Option C

Explanation: add() inserts new elements into an ArrayList.

Q24

Which reference indicates an object is not pointing anywhere?

A void
B delete
C null
D none

Answer: Option C

Explanation: null means the reference variable does not refer to any object.

Q25

Which of these is not a Java collection interface?

A List
B Set
C Map
D Structure

Answer: Option D

Explanation: Structure is not part of Java Collections Framework.

Q26

Which class stores elements in sorted order?

A TreeSet
B HashSet
C ArrayList
D Vector

Answer: Option A

Explanation: TreeSet stores elements in ascending sorted order.

Q27

Which method removes all elements from a collection?

A clear()
B delete()
C removeAll()
D empty()

Answer: Option A

Explanation: clear() empties a collection.

Q28

Which concept allows objects to take many forms?

A Abstraction
B Encapsulation
C Polymorphism
D Inheritance

Answer: Option C

Explanation: Polymorphism allows the same method to behave differently.

Q29

Which operator is used to access object members?

A ::
B ->
C .
D :

Answer: Option C

Explanation: The dot operator accesses object methods and variables.

Q30

Which collection allows FIFO (First-In, First-Out) order?

A List
B Queue
C Set
D Map

Answer: Option B

Explanation: A Queue follows FIFO ordering.

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Objects and Collections Questions and Answers

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