Java Collections Framework: Master Data Structures and Algorithms

Question 1

Which of the following collection types is not part of the Java Collections Framework?

Accepted Answer

Array

Answer

List

Answer

Set

Answer

Map

Question 2

Which interface in the Java Collections Framework represents an ordered collection of elements?

Accepted Answer

List

Answer

Set

Answer

Map

Answer

Queue

Question 3

Which method is used to add an element to a HashSet in Java?

Accepted Answer

add()

Answer

put()

Answer

insert()

Answer

append()

Question 4

Which class implements the Queue interface in the Java Collections Framework?

Accepted Answer

LinkedList

Answer

ArrayList

Answer

HashMap

Answer

HashSet

Question 5

What is the primary purpose of the Comparator interface in Java?

Accepted Answer

To compare objects and determine their order

Answer

To sort elements in a collection

Answer

To create new collections

Answer

To remove duplicate elements from a collection

Question 6

Which method is used to iterate over the key-value pairs of a Map in Java?

Accepted Answer

entrySet()

Answer

iterator()

Answer

forEach()

Answer

stream()

Question 7

What is the key difference between HashMap and TreeMap in Java?

Accepted Answer

TreeMap orders its keys in ascending order, while HashMap does not.

Answer

HashMap allows duplicate keys, while TreeMap does not.

Answer

HashMap is synchronized, while TreeMap is not.

Answer

There is no difference between HashMap and TreeMap.

Question 8

Which annotation in Java can be used to mark a class as thread-safe?

Accepted Answer

@ThreadSafe

Answer

@Synchronized

Answer

@Concurrent

Answer

@Atomic

Question 9

Which Java interface represents a collection of unique, unordered elements?

Accepted Answer

Set

Answer

List

Answer

Queue

Answer

Map

Question 10

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

Accepted Answer

To arrange elements in ascending order

Answer

To add new elements to a collection

Answer

To remove duplicate elements from a collection

Answer

To search for specific elements in a collection

Question 11

Which of the following classes is an implementation of the Map interface?

Accepted Answer

HashMap

Answer

LinkedList

Answer

PriorityQueue

Answer

TreeSet

Question 12

Which Java interface represents a collection that maintains elements in the order they were added?

Accepted Answer

List

Answer

Queue

Answer

Stack

Answer

Set

Question 13

Which method in the Collections class can determine if a collection is empty?

Accepted Answer

isEmpty()

Answer

size()

Answer

contains()

Answer

add()

Question 14

Which collection interface allows storing key-value pairs, where keys are unique?

Accepted Answer

Map

Answer

List

Answer

Set

Answer

Queue

Question 15

Which collection interface is most suited for implementing a last-in, first-out (LIFO) data structure?

Accepted Answer

Stack

Answer

LinkedList

Answer

ArrayList

Answer

Queue

Question 16

What is the primary purpose of the 'Iterable' interface?

Accepted Answer

To represent a collection that can be iterated over using a foreach loop

Answer

To represent a collection that can be sorted

Answer

To represent a collection that can be searched

Answer

To represent a collection that can be stored in a database

Question 17

Which of the following is NOT an advantage of utilizing the Java Collections Framework?

Accepted Answer

Reduced memory consumption

Answer

Enhanced code readability

Answer

Increased code efficiency

Answer

Improved concurrency support

Question 18

In the Java Collections Framework, which interface represents a sorted set of unique elements arranged in ascending order?

Accepted Answer

TreeSet

Answer

HashSet

Answer

LinkedHashSet

Question 19

In the Java Collections Framework, which class represents an ordered list with elements that can be accessed by index?

Accepted Answer

List

Answer

Set

Answer

Queue

Answer

Map

Question 20

Which collection type maintains a unique set of elements, meaning duplicate values are not allowed?

Accepted Answer

Set

Answer

List

Answer

Queue

Answer

Map

Question 21

In the Map interface, which method retrieves the associated value for a specified key?

Accepted Answer

get()

Answer

getValue()

Answer

fetch()

Answer

retrieve()

Question 22

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

Accepted Answer

Increased memory consumption

Answer

Automatic garbage collection

Answer

Enhanced thread safety

Answer

Improved code organization

Question 23

What is the time complexity of adding an element to the beginning of a LinkedList?

Accepted Answer

O(1)

Answer

O(n)

Answer

O(log n)

Answer

O(n^2)

Question 24

Which data structure is suitable for implementing a queue data structure?

Accepted Answer

LinkedList

Answer

ArrayList

Answer

HashMap

Answer

TreeSet

Question 25

What is the purpose of the Collections.min() method?

Accepted Answer

To find the minimum element in a collection

Answer

To sort a collection in ascending order

Answer

To remove duplicates from a collection

Answer

To reverse a collection

Question 26

Which method in the Set interface allows you to determine if the set contains a specific element?

Accepted Answer

contains()

Answer

hasElement()

Answer

includes()

Answer

isPresent()

Question 27

What is the purpose of the Comparator interface?

Accepted Answer

To specify a custom comparison order for objects

Answer

To sort collections in ascending order

Answer

To find the maximum element in a collection

Answer

To remove duplicates from a collection

Question 28

Which Java Collections Framework interface represents a collection of unique elements?

Accepted Answer

Set

Answer

List

Answer

Map

Answer

Queue

Question 29

What method is used to add an element to a List?

Accepted Answer

add()

Answer

insert()

Answer

push()

Answer

append()

Question 30

Which data structure is ideal for storing key-value pairs?

Accepted Answer

Map

Answer

Set

Answer

List

Answer

Queue

Question 31

What is the time complexity of HashSet's contains() method?

Accepted Answer

O(1)

Answer

O(log n)

Answer

O(n)

Answer

O(n^2)

Question 32

Which of the following is NOT an advantage of generics in Java Collections Framework?

Accepted Answer

Boosted performance

Answer

Enhanced type safety

Answer

Simplified code

Answer

Greater flexibility

Question 33

What is the primary purpose of the Comparator interface?

Accepted Answer

Comparing two objects

Answer

Sorting a collection

Answer

Filtering a collection

Answer

Transforming a collection

Question 34

What is a common practical application of the Java Collections Framework?

Accepted Answer

Storing and manipulating data in applications

Answer

Performing mathematical operations on collections

Answer

Creating graphical user interfaces

Answer

Managing database connections

Question 35

Within the Java Collections Framework, what is the primary distinction between iterators and collections?

Accepted Answer

Iterators safely traverse elements, while collections store elements.

Answer

Collections store elements, while iterators add and remove elements.

Answer

Collections traverse elements, while iterators store elements.

Answer

Collections can be iterated over directly, making iterators redundant.

Question 36

You need to choose a collection type that supports fast insertion and deletion of elements at the beginning of the collection. Which collection type should you select?

Accepted Answer

LinkedList

Answer

ArrayList

Answer

HashSet

Answer

HashMap

Question 37

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

Accepted Answer

Array

Answer

List

Answer

Set

Answer

Map

Question 38

Which interface must a class implement to be usable as a Map key?

Accepted Answer

Comparable

Answer

Comparator

Answer

Serializable

Answer

Iterable

Question 39

What's the advantage of a HashMap over a TreeMap?

Accepted Answer

HashMaps are faster for insertions and lookups.

Answer

TreeMaps are faster for insertions and lookups.

Answer

HashMaps maintain key insertion order.

Answer

TreeMaps maintain key insertion order.

Question 40

Which class represents a set of unique, immutable objects?

Accepted Answer

ImmutableSet

Answer

HashSet

Answer

TreeSet

Answer

LinkedHashSet

Question 41

What's the time complexity of finding an element in a HashMap?

Accepted Answer

O(1)

Answer

O(log n)

Answer

O(n)

Answer

O(n^2)

Question 42

Which interface in the Java Collections Framework defines the basic operations for manipulating a group of objects?

Accepted Answer

Collection

Answer

Set

Answer

Map

Answer

List

Question 43

What is the purpose of the HashMap class in Java?

Accepted Answer

Stores key-value pairs for efficient retrieval based on keys

Answer

Provides thread-safe access to elements

Answer

Maintains a sorted order of elements

Question 44

Which method can be used to remove all elements from an ArrayList?

Accepted Answer

clear()

Answer

removeAll()

Answer

flush()

Answer

popAll()

Question 45

Which class in Java implements the SortedSet interface, allowing elements to be sorted based on a specified comparator?

Accepted Answer

TreeSet

Answer

ConcurrentSkipListSet

Answer

HashSet

Answer

LinkedHashSet

Question 46

What is the purpose of the Comparator interface in Java?

Accepted Answer

Defines a comparison mechanism for ordering elements

Answer

Manages concurrent access to elements

Answer

Provides a hash function for elements

Question 47

Which operation has O(1) time complexity for a HashMap in Java?

Accepted Answer

Retrieving a value based on its key

Answer

Inserting a new key-value pair

Answer

Deleting a key-value pair

Question 48

What is the purpose of the Collections.synchronizedList() method in Java?

Accepted Answer

Creates a thread-safe view of a list

Answer

Sorts a list in ascending order

Answer

Converts a list to a set

Question 49

What is the purpose of the Iterator interface in Java?

Accepted Answer

Provides a way to traverse elements of a collection sequentially

Answer

Defines a sorting mechanism for elements

Answer

Manages concurrent access to elements

Question 50

Which interface represents a collection that holds unique elements?

Accepted Answer

Set

Answer

List

Answer

Map

Answer

Queue

Question 51

Which class represents a linked list implementation in Java Collections Framework?

Accepted Answer

LinkedList

Answer

Vector

Answer

Stack

Answer

ArrayDeque

Question 52

Which interface represents a collection designed to store key-value pairs?

Accepted Answer

Map

Answer

Set

Answer

Queue

Answer

List

Question 53

What is the primary purpose of the 'Comparator' interface in the Java Collections Framework?

Accepted Answer

To define a custom sorting order for objects within a collection

Answer

To create new collection instances dynamically

Answer

To iterate through collections with custom logic

Answer

To compare primitives efficiently

Question 54

Which method is used to remove all elements from a collection in the Java Collections Framework?

Accepted Answer

clear()

Answer

removeAll()

Answer

discard()

Answer

removeFirst()

Question 55

What is a key distinction between 'Lists' and 'Sets' in the Java Collections Framework?

Accepted Answer

Lists allow duplicate elements while Sets do not.

Answer

Lists allow null values while Sets do not.

Answer

Sets are thread-safe while Lists are not.

Answer

Sets are ordered while Lists are not.

Question 56

What is the primary purpose of the 'Collections.sort()' method in the Java Collections Framework?

Accepted Answer

To sort a list of objects based on their natural ordering or a provided 'Comparator'

Answer

To create a new list instance

Answer

To compare two lists for equality

Answer

To reverse the order of a list

Question 57

Which interface represents a collection that provides thread-safe access to its elements?

Accepted Answer

ConcurrentMap

Answer

LinkedHashMap

Answer

HashMap

Answer

TreeMap

Question 58

What is the average time complexity for accessing an element in a 'HashMap' in the Java Collections Framework?

Accepted Answer

O(1)

Answer

O(log n)

Answer

O(n^2)

Answer

O(n)