Java Collections (Basic)

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Questions and Answers

Which data structure implements the First-In-First-Out principle?

Deque

Set

PriorityQueue

Queue (correct)

Which data structure can be used as both a queue and a stack?

Deque (correct)

Set

Queue

PriorityQueue

Which data structure is used to process objects based on priority?

Queue

Set

Deque

PriorityQueue (correct)

Which data structure does not allow duplicate elements?

Set Signup and view all the answers

Which data structure uses a hash table for storing elements?

HashSet Signup and view all the answers

Which data structure allows iteration through elements in their order of insertion?

LinkedHashSet Signup and view all the answers

Which data structure maintains elements in ascending order?

TreeSet Signup and view all the answers

Which interface is the root interface for all collection classes?

Iterable Signup and view all the answers

Which interface is implemented by all the classes in the collection framework?

Collection Signup and view all the answers

Which data structure is used to store an ordered collection of objects and allows duplicate values?

List Signup and view all the answers

Which class implements the List interface and is a dynamic array?

ArrayList Signup and view all the answers

Which class is a subclass of Vector and implements the Last-In-First-Out principle?

Stack Signup and view all the answers

Which class implements the List and Deque interfaces and is a linear data structure?

LinkedList Signup and view all the answers

Which package contains all the collections in Java?

java.util Signup and view all the answers

Which method is used to add elements to the end of an ArrayList?

add() Signup and view all the answers

What is the syntax for creating an ArrayList object?

ArrayList objName = new ArrayList(); Signup and view all the answers

Which method is used to access the element at a specified index in an ArrayList?

get() Signup and view all the answers

What does the contains() method check in an ArrayList?

Whether the ArrayList contains the specified element or not Signup and view all the answers

Which method is used to remove specific elements from an ArrayList?

remove() Signup and view all the answers

What does the set() method do in an ArrayList?

Updates an element at a specified index Signup and view all the answers

Which method is used to sort the elements in an ArrayList in ascending order?

sort() Signup and view all the answers

What does the indexOf() method return in an ArrayList?

The index of the specified element Signup and view all the answers

Which method is used to remove all elements from an ArrayList?

clear() Signup and view all the answers

Which of the following is true about Java Collections Framework?

It is used for manipulating data of the collections Signup and view all the answers

Which collections were commonly used before the introduction of Java Collections Framework?

Arrays, Hashtables, and Vectors Signup and view all the answers

What is a collection in Java?

A group of objects represented as a single unit Signup and view all the answers

Why do we need a collection framework in Java?

To represent, store, and manipulate data of the collections Signup and view all the answers

What does the Java Collections Framework provide?

A way to manipulate data independently of implementation details Signup and view all the answers

Which classes and interfaces are defined by the Java Collection framework?

Multiple choice, TreeMap, and HashSet Signup and view all the answers

What is the purpose of the constructors in HashMap?

To create a new HashMap object Signup and view all the answers

Study Notes

Data Structures

A queue implements the First-In-First-Out principle.
An ArrayDeque can be used as both a queue and a stack.
A priority queue is used to process objects based on priority.
A set does not allow duplicate elements.
A HashSet uses a hash table for storing elements.
A List allows iteration through elements in their order of insertion.
A TreeSet maintains elements in ascending order.

Interfaces and Classes

The Collection interface is the root interface for all collection classes.
The Collection interface is implemented by all the classes in the collection framework.
An ArrayList is used to store an ordered collection of objects and allows duplicate values.
The ArrayList class implements the List interface and is a dynamic array.
A Stack class is a subclass of Vector and implements the Last-In-First-Out principle.
An ArrayDeque implements the List and Deque interfaces and is a linear data structure.

Methods and Operations

The add() method is used to add elements to the end of an ArrayList.
The syntax for creating an ArrayList object is ArrayList<> arrayList = new ArrayList<>();.
The get() method is used to access the element at a specified index in an ArrayList.
The contains() method checks if an ArrayList contains a specified element.
The remove() method is used to remove specific elements from an ArrayList.
The set() method replaces an element at a specified index in an ArrayList.
The sort() method is used to sort the elements in an ArrayList in ascending order.
The indexOf() method returns the index of the first occurrence of a specified element in an ArrayList.
The clear() method is used to remove all elements from an ArrayList.

Java Collections Framework

The java.util package contains all the collections in Java.
The Java Collections Framework provides a set of classes and interfaces for working with collections.
The Java Collections Framework provides a way to work with collections in a generic and type-safe manner.
The Java Collections Framework defines several interfaces and classes, including Collection, List, Set, Map, and others.
The purpose of the constructors in HashMap is to initialize the map with an initial capacity and load factor.

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Description

Test your knowledge of Queues and Deques in the Collection framework. Learn about the core principles and implementations of these data structures.