Java Collections Framework: Master Data Structures and Algorithms

Question 1

Which of the following is a **disadvantage** of using the Java Collections Framework?

Accepted Answer

Increased code complexity

Answer

Enhanced code readability and maintainability

Answer

Improved code efficiency and performance

Answer

Optimized memory utilization

Question 2

Which data structure in the Java Collections Framework typically offers the fastest search performance?

Accepted Answer

HashSet

Answer

ArrayList

Answer

LinkedList

Answer

HashMap

Question 3

When using an iterator to traverse a collection in Java, what is a possible outcome if the collection is modified during iteration?

Accepted Answer

ConcurrentModificationException

Answer

The iterator automatically updates to reflect the changes.

Answer

The iteration proceeds without any impact.

Question 4

Which of the following is **not** a collection type in the Java Collections Framework?

Accepted Answer

Array

Answer

List

Answer

Set

Answer

Map

Question 5

Which interface represents a collection of **unique** elements?

Accepted Answer

Set

Answer

Collection

Answer

List

Answer

Map

Question 6

Which class provides a mapping between a **key** and a **value**?

Accepted Answer

Map

Answer

Set

Answer

List

Answer

Collection

Question 7

What is the time complexity of **searching** for an element in a HashMap?

Accepted Answer

O(1)

Answer

O(log n)

Answer

O(n)

Answer

O(n^2)

Question 8

Which method can be used to sort a list in **ascending** order?

Accepted Answer

Collections.sort()

Answer

sort()

Answer

orderBy()

Answer

asList()

Question 9

What is the purpose of the Comparator interface?

Accepted Answer

To define a **custom** sorting order

Answer

To compare two objects for equality

Answer

To iterate over a collection

Answer

To create a new collection

Question 10

Which exception is thrown **when** an operation is performed on an empty collection?

Accepted Answer

EmptyCollectionException

Answer

IndexOutOfBoundsException

Answer

NullPointerException

Answer

IllegalArgumentException

Question 11

What is the difference between a concurrent and a synchronized collection?

Accepted Answer

Concurrent collections are thread-safe while synchronized collections are **not**

Answer

Synchronized collections are thread-safe while concurrent collections are not

Answer

There is no difference between concurrent and synchronized collections

Answer

Concurrent collections are faster than synchronized collections

Question 12

Which class provides an immutable and **thread-safe** view of a collection?

Accepted Answer

Collections.unmodifiableList()

Answer

Collections.synchronizedList()

Answer

Collections.emptyList()

Answer

Collections.singletonList()

Question 13

Which of the following real-world scenarios best exemplifies the effective application of the Java Collections Framework?

Accepted Answer

Managing student records in a school database system

Answer

Generating a sequence of random numbers for lottery simulations

Answer

Developing a novel data compression algorithm

Question 14

Which interface represents a collection that stores unique elements without duplicates?

Accepted Answer

java.util.Set

Answer

java.util.List

Answer

java.util.Map

Answer

java.util.Queue

Question 15

Which class implements the Queue interface and follows the FIFO (First-In-First-Out) data structure principle?

Accepted Answer

java.util.LinkedList

Answer

java.util.ArrayList

Answer

java.util.HashSet

Answer

java.util.HashMap

Question 16

What is the primary advantage of using a Map interface over a List interface when working with key-value pairs?

Accepted Answer

Efficient retrieval of values using their corresponding keys

Answer

Automatic sorting of keys

Answer

Ability to store duplicate keys

Answer

Higher memory efficiency

Question 17

What is the key difference between a HashMap and a LinkedHashMap in terms of their functionality?

Accepted Answer

LinkedHashMap preserves the order of insertion while HashMap does not

Answer

HashMap is faster than LinkedHashMap

Answer

LinkedHashMap is more memory-efficient than HashMap

Answer

There is no difference between HashMap and LinkedHashMap

Question 18

What is the main purpose of the Iterator interface in the Java Collections Framework?

Accepted Answer

To sequentially traverse elements in a collection

Answer

To modify elements in a collection

Answer

To create new collections

Answer

To search for elements in a collection

Question 19

Which class in the Java Collections Framework is used to create a thread-safe List?

Accepted Answer

java.util.Vector

Answer

java.util.ArrayList

Answer

java.util.LinkedList

Answer

java.util.Collections

Question 20

What is the time complexity for searching an element in a HashSet?

Accepted Answer

O(1)

Answer

O(n)

Answer

O(log n)

Answer

O(n^2)

Question 21

Which method of the Map interface returns a Set representation of all the keys contained in the map?

Accepted Answer

keySet()

Answer

values()

Answer

entrySet()

Answer

getKeys()

Question 22

In the Java Collections Framework, which interface represents a group of distinct elements unordered?

Accepted Answer

Set

Answer

List

Answer

Queue

Answer

Map

Question 23

Which method of the List interface is used to add a new element to the collection?

Accepted Answer

add()

Answer

insert()

Answer

append()

Answer

push()

Question 24

Within the Java Collections Framework, which class is thread-safe for accessing a Map?

Accepted Answer

ConcurrentHashMap

Answer

HashMap

Answer

TreeMap

Answer

LinkedHashMap

Question 25

Which interface is used to represent a collection of key-value pairs?

Accepted Answer

Map

Answer

Dictionary

Answer

Table

Answer

Cache

Question 26

Which class is suitable for implementing a Last-In-First-Out (LIFO) structure?

Accepted Answer

Stack

Answer

ArrayList

Answer

LinkedList

Answer

Vector

Question 27

What is the primary function of the Collections.sort() method?

Accepted Answer

Sorting a collection of elements in ascending order

Answer

Sorting a collection of elements in descending order

Answer

Shuffling a collection of elements

Answer

Creating a new collection with sorted elements

Question 28

Which interface is used to represent a collection that can be iterated over sequentially?

Accepted Answer

Iterable

Answer

Enumerator

Answer

ListIterator

Answer

Collection

Question 29

What is the key difference between an ArrayList and a LinkedList?

Accepted Answer

ArrayList provides faster random access, while LinkedList provides faster insertion/deletion

Answer

ArrayList uses an array for storage, while LinkedList uses a linked list

Answer

LinkedList uses an array for storage, while ArrayList uses a linked list

Answer

LinkedList provides faster random access, while ArrayList provides faster insertion/deletion

Question 30

Which interface represents a collection of distinct, unordered elements?

Accepted Answer

Set

Answer

List

Answer

Map

Answer

Collection

Question 31

Which class implements the List interface and allows random access to elements based on their index?

Accepted Answer

ArrayList

Answer

LinkedList

Answer

HashMap

Answer

TreeSet

Question 32

Which collection type preserves the order in which elements were added?

Accepted Answer

LinkedHashSet

Answer

HashMap

Answer

ArrayList

Answer

TreeSet

Question 33

Which interface represents a collection of key-value pairs?

Accepted Answer

Map

Answer

Set

Answer

List

Answer

Queue

Question 34

Which class implements the Map interface and uses a hashing mechanism for efficient key-based lookups?

Accepted Answer

HashMap

Answer

LinkedHashMap

Answer

ConcurrentHashMap

Answer

TreeMap

Question 35

Which interface represents a queue, a First-In-First-Out (FIFO) data structure?

Accepted Answer

Queue

Answer

Deque

Answer

PriorityQueue

Answer

List

Question 36

Which class implements the Deque interface and supports adding and removing elements from both ends?

Accepted Answer

ArrayDeque

Answer

LinkedList

Answer

PriorityQueue

Answer

LinkedHashSet

Question 37

Which method can be used to sort a List of objects into ascending order?

Accepted Answer

Collections.sort()

Answer

sort()

Answer

compare()

Answer

Arrays.sort()

Question 38

In Java generics, what is type erasure and how does it affect the Java Collections Framework?

Accepted Answer

Type erasure allows generic collections to be stored in arrays of their raw types, requiring casting to access elements.

Answer

Type erasure preserves generic type information at runtime, ensuring strong type safety.

Answer

Type erasure affects only the source code, leaving generic type information in the compiled bytecode.

Question 39

Which interface in the Java Collections Framework represents a collection of unique elements, with no defined order?

Accepted Answer

Set

Answer

Collection

Answer

List

Answer

Map

Question 40

Which method in the Java Collections Framework is used to add an element to a list?

Accepted Answer

add()

Answer

push()

Answer

append()

Answer

insert()

Question 41

Which of the following is NOT a type of map implementation in the Java Collections Framework?

Accepted Answer

Dictionary

Answer

HashMap

Answer

TreeMap

Answer

LinkedHashMap

Question 42

Which interface in the Java Collections Framework represents a collection that maintains insertion order of its elements?

Accepted Answer

List

Answer

Collection

Answer

Set

Answer

Queue

Question 43

Which method in the Java Collections Framework is used to retrieve the first element from a queue?

Accepted Answer

peek()

Answer

poll()

Answer

remove()

Answer

get()

Question 44

Which class in the Java Collections Framework represents an immutable list?

Accepted Answer

ImmutableList

Answer

ArrayList

Answer

LinkedList

Answer

Collections

Question 45

Which Java Collections Framework interface is used to perform operations on a collection while iterating through its elements?

Accepted Answer

Iterator

Answer

Comparator

Answer

Transformer

Answer

Accumulator

Question 46

In the Java Collections Framework, which interface represents a collection of unique and unordered elements?

Accepted Answer

Set

Answer

Array

Answer

List

Answer

Map

Question 47

Within the Java Collections Framework, which class implements the Queue interface adhering to the first-in-first-out (FIFO) principle?

Accepted Answer

LinkedList

Answer

HashSet

Answer

ArrayList

Answer

HashMap

Question 48

In the Java Collections Framework, which method of the Collections class is used to sort a list in ascending order?

Accepted Answer

sort()

Answer

order()

Answer

sortAsc()

Answer

sortDesc()

Question 49

Which interface in the Java Collections Framework represents a data structure that maps unique keys to values?

Accepted Answer

Map

Answer

List

Answer

Queue

Answer

Set

Question 50

In the Java Collections Framework, which class implements the Deque interface?

Accepted Answer

ArrayDeque

Answer

LinkedQueue

Answer

PriorityQueue

Answer

Stack

Question 51

Which interface in the Java Collections Framework represents a collection of ordered and indexed elements?

Accepted Answer

List

Answer

Map

Answer

Queue

Answer

Set

Question 52

In the HashSet class of Java Collections Framework, which method can be used to remove all elements from the set?

Accepted Answer

clear()

Answer

remove()

Answer

removeAll()

Answer

delete()

Question 53

Within the Java Collections Framework, which class is a synchronized implementation of the Map interface?

Accepted Answer

ConcurrentHashMap

Answer

HashMap

Answer

LinkedHashMap

Answer

TreeMap

Question 54

In the ArrayList class of Java Collections Framework, which method is used to retrieve the element at a specified index?

Accepted Answer

get(int index)

Answer

get()

Answer

fetch()

Answer

getElement()

Question 55

Which interface in the Java Collections Framework represents a data structure following the last-in-first-out (LIFO) principle?

Accepted Answer

Stack

Answer

Queue

Answer

Set

Answer

List