Dart Collections:Types of Collections

Dart Collections: Comprehensive Guide to Lists, Sets, Queues, and LinkedLists

Introduction:

Learn how to effectively utilize Dart collections in your applications. From the basics of Lists and Sets to more advanced concepts like Queues and LinkedLists, this comprehensive guide covers everything you need to know about working with collections in Dart.

In Dart, collections are used to store multiple values in a single variable.

Dart provides several types of collections, each with its own characteristics and use cases.

Types of Dart collections

The main collection types in Dart include:

Dart List

• A list is an ordered collection of objects that allows duplicates.
• Lists in Dart are similar to arrays in other programming languages.
• They are indexed, meaning you can access elements by their index.
• Lists can grow or shrink dynamically.

dart

List<int> numbers = [1, 2, 3, 4, 5];

let’s break down the Dart List step by step:

Definition:

A List in Dart is an ordered collection of elements.
Elements in a list are indexed starting from 0 for the first element, 1 for the second element, and so on.

Declaration:

• You can declare a list using the List keyword followed by angle brackets (<>) containing the type of elements the list will hold.
• Optionally, you can initialize the list with elements using square brackets ([]).

dart

List<int> numbers = [1, 2, 3, 4, 5];

Dynamic Sizing:

• Lists in Dart can dynamically grow or shrink in size.
• You can add elements to the end of the list using the add() method or using the list’s square bracket syntax.
• You can remove elements using methods like remove() or removeAt().

dart

numbers.add(6); // Adds 6 to the end of the list
numbers.removeAt(2); // Removes the element at index 2 (3)

Accessing Elements in Dart list:

You can access elements in a list using their index.
Indexing starts from 0.

Dart throws an IndexOutOfRangeException if you try to access an index that is out of bounds.

dart

int thirdElement = numbers[2]; // Accessing the third element (index 2)

Length of dart list :

• You can get the length of a list using the length property.
• This property returns the number of elements in the list.

dart

int length = numbers.length; // Length of the list

Iteration over Dart list:

You can iterate over the elements of a list using various methods like for-in loop, forEach(), or map().

dart

for (int number in numbers) {
print(number);
}

numbers.forEach((number) {
print(number);
});

Dart List Manipulation:

Dart provides various methods to manipulate lists, such as sort(), indexOf(), contains(), addAll(), etc.
dart

numbers.sort(); // Sorts the list
int index = numbers.indexOf(4); // Finds the index of 4
bool containsThree = numbers.contains(3); // Checks if the list contains 3

Dart List Equality:

Lists are compared by checking if they contain the same elements in the same order.
dart

List<int> otherList = [1, 2, 3, 4, 5];
bool equal = numbers == otherList; // Checks if the lists are equal

These are the fundamental aspects of working with lists in Dart. Understanding these steps will help you effectively utilize lists in your Dart programs.

complete code example about Dart List:

Here’s a complete Dart code example demonstrating various operations with lists:

dart

void main() {
// Declaration and Initialization of a list
List<int> numbers = [1, 2, 3, 4, 5];

// Add an element to the end of the list
numbers.add(6);

// Remove an element at a specific index
numbers.removeAt(2);

// Accessing elements of the list
int thirdElement = numbers[2];

// Getting the length of the list
int length = numbers.length;

// Iterating over the elements of the list using a for-in loop
print("Elements of the list:");
for (int number in numbers) {
print(number);
}

// Sorting the list
numbers.sort();

// Finding the index of an element
int index = numbers.indexOf(4);

// Checking if the list contains a specific element
bool containsThree = numbers.contains(3);

// Creating another list
List<int> otherList = [1, 2, 3, 4, 5];

// Checking equality of two lists
bool equal = numbers == otherList;

// Printing results
print("\nAfter operations:");
print("List: $numbers");
print("Third Element: $thirdElement");
print("Length of the List: $length");
print("Index of 4: $index");
print("Contains 3: $containsThree");
print("Lists are equal: $equal");
}

This code demonstrates the basic operations you can perform with Dart lists, such as adding and removing elements, accessing elements by index, getting the length of the list, iterating over elements, sorting, finding the index of an element, checking for element existence, and comparing lists for equality.

Another example with explanation

Here’s another Dart code example with explanations for each step:

dart

void main() {
// Step 1: Declaration and Initialization of a list
List<String> fruits = ['Apple', 'Banana', 'Orange'];

// Step 2: Adding elements to the list
fruits.add('Mango');
fruits.addAll(['Grapes', 'Pineapple']);

// Step 3: Accessing elements of the list
String secondFruit = fruits[1]; // Accessing the second element of the list

// Step 4: Getting the length of the list
int length = fruits.length;

// Step 5: Iterating over the elements of the list using a for loop
print('List of Fruits:');
for (String fruit in fruits) {
print(fruit);
}

// Step 6: Checking if the list contains a specific element
bool containsBanana = fruits.contains('Banana');

// Step 7: Removing elements from the list
fruits.remove('Orange');
fruits.removeAt(2); // Remove the element at index 2

// Step 8: Printing results
print('\nAfter operations:');
print('List of Fruits: $fruits');
print('Second Fruit: $secondFruit');
print('Length of the List: $length');
print('Does it contain Banana? $containsBanana');
}

Explanation for each step:

Declaration and Initialization of a List:

We declare and initialize a list of strings named fruits with initial elements ‘Apple’, ‘Banana’, and ‘Orange’.

Adding Elements to the List:

We add two more fruits, ‘Mango’ using add() and a list of fruits [‘Grapes’, ‘Pineapple’] using addAll().

Accessing Elements of the List:

We access the second element of the list using index 1 and store it in the variable secondFruit.

Getting the Length of the List:

We get the length of the list using the length property and store it in the variable length.

Iterating Over the Elements of the List:

We use a for-in loop to iterate over each fruit in the fruits list and print them.

Checking if the List Contains a Specific Element:

We use the contains() method to check if the list contains the fruit ‘Banana’ and store the result in the variable containsBanana.

Removing Elements from the List:

We remove the fruit ‘Orange’ using the remove() method and the fruit at index 2 using removeAt().
Printing Results:

Finally, we print the updated list of fruits, the second fruit, the length of the list, and whether it contains ‘Banana’.

Dart Set:

• A set is an unordered collection of unique objects.
• Sets do not allow duplicate elements.
• Sets can be useful when you need to ensure uniqueness or perform set operations such as union, intersection, and difference.

dart

Set<String> uniqueNames = {'Omar', 'gogo', 'Adam', 'Elin'};

Step by step How to create Lis in Dart?

Let’s break down the Dart Set step by step:

Definition Dart set:

A Set in Dart is an unordered collection of unique elements.
Each element in the set must be unique, meaning no duplicates are allowed.

Declaration set in Dart:

• You can declare a set using the Set keyword followed by angle brackets (<>) containing the type of elements the set will hold.
• Optionally, you can initialize the set with elements using curly braces ({}).

dart

Set<String> uniqueNames = {'Omar', 'Gogo', 'Adam'};

Adding Elements to dart set:

You can add elements to a set using the add() method.
If you attempt to add a duplicate element, the set will remain unchanged since duplicates are not allowed.
dart

uniqueNames.add(‘Ahmed’);

Removing Elements:

• You can remove elements from a set using the remove() method.
• If the element exists in the set, it will be removed; otherwise, the set remains unchanged.

dart

uniqueNames.remove('Omar');

Dart Set Operations:

Sets support various operations such as union, intersection, difference, and subset.

These operations allow you to combine, compare, or manipulate sets.

dart

Set<String> otherNames = {'Ali', 'Kamal', 'Khaleid'};

// Union
Set<String> unionSet = uniqueNames.union(otherNames);

// Intersection
Set<String> intersectionSet = uniqueNames.intersection(otherNames);

// Difference
Set<String> differenceSet = uniqueNames.difference(otherNames);

// Subset
bool isSubset = uniqueNames.isSubsetOf(otherNames);

Iterating Over Dart setElements:

You can iterate over the elements of a set using various methods like for-in loop or forEach().

dart

print('Elements of the set:');
for (String name in uniqueNames) {
print(name);
}

Dart Set Equality:

Sets are compared by checking if they contain the same elements, regardless of the order.
dart

Set<String> otherSet = {'Omar', 'Gogo', 'Adam'};
bool equal = uniqueNames == otherSet;

These are the fundamental aspects of working with sets in Dart.
Understanding these steps will help you effectively utilize sets in your Dart programs.

complete code  about set with explanation

Here’s a complete Dart code example demonstrating various operations with sets, along with explanations for each step:

dart

void main() {
// Step 1: Declaration and Initialization of a set
Set<String> uniqueNames = {'Gogo', 'Omar', 'Adam'};

// Step 2: Adding elements to the set
uniqueNames.add('David');
uniqueNames.addAll({'Eve', 'Frank'});

// Step 3: Removing elements from the set
uniqueNames.remove('Omar');

// Step 4: Set Operations
Set<String> otherNames = {'David', 'Eve', 'Grace'};

// Union of two sets
Set<String> unionSet = uniqueNames.union(otherNames);

// Intersection of two sets
Set<String> intersectionSet = uniqueNames.intersection(otherNames);

// Difference between two sets
Set<String> differenceSet = uniqueNames.difference(otherNames);

// Subset check
bool isSubset = uniqueNames.isSubsetOf(otherNames);

// Step 5: Iterating over elements of the set
print('Elements of the set:');
uniqueNames.forEach((name) => print(name));

// Step 6: Set Equality check
Set<String> otherSet = {'Gogo', 'Adam', 'David', 'Eve', 'Frank'};
bool equal = uniqueNames == otherSet;

// Step 7: Printing results
print('\nAfter operations:');
print('Set of Names: $uniqueNames');
print('Union of Sets: $unionSet');
print('Intersection of Sets: $intersectionSet');
print('Difference of Sets: $differenceSet');
print('Is uniqueNames a subset of otherNames? $isSubset');
print('Are the sets equal? $equal');
}

Explanation for each step:

Declaration and Initialization of a Set:

We declare and initialize a set named uniqueNames containing unique names.

Adding Elements to the Set:

We add two more names ‘David’ and ‘Eve’ to the set using the add() method, and another set of names using addAll().

Removing Elements from the Set:

We remove the name ‘Omar’ from the set using the remove() method.

Set Operations:

We perform set operations such as union, intersection, difference, and subset check between uniqueNames and otherNames.

Iterating Over Elements of the Set:

We use the forEach() method to iterate over each name in the uniqueNames set and print them.

Set Equality Check:

We compare whether uniqueNames set is equal to otherSet set.
Printing Results:

Finally, we print the sets after performing operations along with the results of set operations and set equality check.

Dart Map:

• A map is a collection of key-value pairs where each key is unique.
• Maps are also known as dictionaries or associative arrays in other programming languages.
• They allow you to associate keys with values for efficient retrieval.

dart

Map<String, int> ages = {
'Omar': 20,
'Gogo': 17,
'Adam': 5,
};

How to create Map in Dart step by step?

Let’s break down the Dart Map step by step:

Definition of Dart map:

• A Map in Dart is a collection of key-value pairs where each key is unique.
• It is also known as a dictionary or associative array in other programming languages.

Declaration of Dart map:

• You can declare a map using the Map keyword followed by angle brackets (<>) containing the types of the keys and values the map will hold.
• Optionally, you can initialize the map with key-value pairs using curly braces ({}) and separating keys and values with colons (:).

dart

Map<String, int> ages = {
'Gogo': 17,
'Omar': 20,
'Adam': 5,
};

Adding and Updating Entries:

• You can add or update entries in a map by assigning a value to a key.
• If the key already exists, the value will be updated; otherwise, a new key-value pair will be added.

dart

ages['Omar'] = 20; // Adds a new entry for 'Omar'
ages['Gogo'] = 20; // Updates the value for 'Gogo'

Accessing Values:

You can access the value associated with a key in a map using square brackets ([]) with the key inside.
If the key does not exist, Dart returns null.
dart

int ageOfOmar = ages['Omar']; // Accessing the age of 'Omar'

Removing Entries:

You can remove entries from a map using the remove() method, passing the key to be removed.
dart

ages.remove('Adam'); // Removes the entry for 'Adam'

Iterating Over Entries:

• You can iterate over the key-value pairs of a map using a forEach() loop.
• The loop function receives two parameters: the key and the value.

dart

ages.forEach((name, age) {
print('$name is $age years old');
});

Dart Map Operations:

Maps support various operations such as getting the keys, values, or entries of the map.
dart

Set<String> names = ages.keys.toSet(); // Get the set of names
List<int> agesList = ages.values.toList(); // Get the list of ages

Dart Map Equality:

Maps are compared by checking if they contain the same key-value pairs.
dart

Map<String, int> otherAges = {'Gogo': 20, 'Omar': 25, 'David': 40};
bool equal = ages == otherAges; // Checks if the maps are equal

These are the fundamental aspects of working with maps in Dart. Understanding these steps will help you effectively utilize maps in your Dart programs.

complete example about Map:with explanation

Here’s a complete Dart code example demonstrating various operations with maps, along with explanations for each step:

dart

void main() {
// Step 1: Declaration and Initialization of a map
Map<String, int> ages = {
'Gogo': 20,
'Omar': 25,
'Adam': 35,
};

// Step 2: Adding and Updating Entries
ages['David'] = 40; // Adds a new entry for 'David'
ages['Gogo'] = 31; // Updates the value for 'Gogo'

// Step 3: Accessing Values
int ageOfOmar = ages['Omar']; // Accessing the age of 'Omar'

// Step 4: Removing Entries
ages.remove('Adam'); // Removes the entry for 'Adam'

// Step 5: Iterating Over Entries
print('Entries of the map:');
ages.forEach((name, age) {
print('$name is $age years old');
});

// Step 6: Map Operations
Set<String> names = ages.keys.toSet(); // Get the set of names
List<int> agesList = ages.values.toList(); // Get the list of ages

// Step 7: Map Equality
Map<String, int> otherAges = {'Gogo': 31, 'Omar': 25, 'David': 40};
bool equal = ages == otherAges; // Checks if the maps are equal

// Step 8: Printing results
print('\nAfter operations:');
print('Map of Ages: $ages');
print('Age of Omar: $ageOfOmar');
print('Set of Names: $names');
print('List of Ages: $agesList');
print('Are the maps equal? $equal');
}

Explanation for each step:

Declaration and Initialization of a Map:

We declare and initialize a map named ages with keys as names (strings) and values as ages (integers).

Adding and Updating Entries:

We add a new entry for ‘David’ and update the value for ‘Gogo’.

Accessing Values:

We access the age of ‘Omar’ by retrieving the value associated with the key ‘Omar’.

Removing Entries:

We remove the entry for ‘Adam’ from the map.

Iterating Over Entries:

We iterate over the key-value pairs of the map and print each name and age.

Map Operations:

We obtain the set of names and the list of ages from the map using keys and values properties respectively.

Map Equality:

We compare whether the ages map is equal to the otherAges map.

Printing Results:

Finally, we print the map after performing operations along with other results such as the age of Omar, set of names, list of ages, and the result of map equality check.

Dart Queue:

• A queue is a collection that represents a first-in, first-out (FIFO) ordering.
• Elements are added to the back of the queue and removed from the front.
• Dart provides the Queue class in the dart:collection library for working with queues.

dart

import 'dart:collection';

Queue<int> queue = Queue();
queue.addAll([1, 2, 3, 4, 5]);

How to create Queue in Dart ?
Queue: step by step

Let’s break down the usage of a Queue in Dart step by step:

Import the dart:collection library:

Dart’s Queue is provided as part of the dart:collection library.

Therefore, you need to import this library to use the Queue.
dart

import 'dart:collection';

Create a Queue instance:

You can create a Queue instance using the Queue class constructor.
dart

Queue<int> queue = Queue();

Add elements to the Queue:

You can add elements to the Queue using the add() method.
This method adds elements to the back of the Queue.
dart

queue.add(1);
queue.add(2);
queue.add(3);

Remove elements from the Queue:

You can remove elements from the Queue using the removeFirst() or removeLast() methods.
removeFirst() removes the first element in the Queue, while removeLast() removes the last element.
dart

int firstElement = queue.removeFirst();
int lastElement = queue.removeLast();

Access elements in the Queue:

You can access elements in the Queue using subscript notation ([]) or by iterating over the Queue.
dart

int secondElement = queue.elementAt(0);

Check if the Queue is empty:

You can check if the Queue is empty using the isEmpty property.
dart

bool isEmpty = queue.isEmpty;

Get the length of the Queue:

You can get the length of the Queue using the length property.
dart

int length = queue.length;

Iterate over elements in the Queue:

You can iterate over elements in the Queue using a for-in loop or the forEach() method.
dart

queue.forEach((element) {
print(element);
});

Clear the Queue:

You can clear all elements from the Queue using the clear() method.
dart

queue.clear();

Other Queue operations:

Dart’s Queue class provides other methods such as addAll(), contains(), removeWhere(), retainWhere(), etc., for additional operations on the Queue.

These steps cover the basic usage of a Queue in Dart. Understanding these steps will help you effectively utilize Queues in your Dart programs.

complete example about:Queue with explanation

Here’s a complete Dart code example demonstrating various operations with a Queue, along with explanations for each step:

dart

import 'dart:collection';

void main() {
// Step 1: Create a Queue instance
Queue<int> queue = Queue();

// Step 2: Add elements to the Queue
queue.add(1);
queue.add(2);
queue.add(3);

// Step 3: Remove elements from the Queue
int firstElement = queue.removeFirst();
int lastElement = queue.removeLast();

// Step 4: Access elements in the Queue
int secondElement = queue.elementAt(0);

// Step 5: Check if the Queue is empty
bool isEmpty = queue.isEmpty;

// Step 6: Get the length of the Queue
int length = queue.length;

// Step 7: Iterate over elements in the Queue
print('Elements of the Queue:');
queue.forEach((element) {
print(element);
});

// Step 8: Clear the Queue
queue.clear();

// Step 9: Printing results
print('\nAfter operations:');
print('First Element: $firstElement');
print('Last Element: $lastElement');
print('Second Element: $secondElement');
print('Is the Queue empty? $isEmpty');
print('Length of the Queue: $length');
}

Explanation for each step:

Create a Queue instance:

We create a Queue instance using the Queue class constructor from the dart:collection library.

Add elements to the Queue:

We add elements 1, 2, and 3 to the Queue using the add() method.

Remove elements from the Queue:

We remove the first and last elements from the Queue using the removeFirst() and removeLast() methods respectively.

Access elements in the Queue:

We access the second element of the Queue using the elementAt() method.

Check if the Queue is empty:

We check if the Queue is empty using the isEmpty property.

Get the length of the Queue:

We get the length of the Queue using the length property.

Iterate over elements in the Queue:

We use the forEach() method to iterate over each element in the Queue and print them.

Clear the Queue:

We clear all elements from the Queue using the clear() method.
Printing results:

Finally, we print the results of the operations performed on the Queue.

Dart LinkedList:

A linked list is a collection of elements, where each element points to the next one in the sequence.

Unlike lists, linked lists in Dart are not built into the language, but you can implement them using custom classes or use packages available through Dart’s package manager, such as linked_list.

How to use LinkedList:step by step?

Let’s go through the steps of using a LinkedList in Dart:

Import the dart:collection library:

Dart’s LinkedList is provided as part of the dart:collection library. You need to import this library to use LinkedList.
dart

import 'dart:collection';

Create a LinkedList instance:

You can create a LinkedList instance using the LinkedList class constructor.
dart

LinkedList<int> linkedList = LinkedList();

Add elements to the LinkedList:

You can add elements to the LinkedList using methods like add(), addFirst(), or addLast().
dart

linkedList.add(1);
linkedList.addLast(2);
linkedList.addFirst(0);

Remove elements from the LinkedList:

You can remove elements from the LinkedList using methods like remove(), removeFirst(), or removeLast().
dart

linkedList.remove(1);
int firstElement = linkedList.removeFirst();
int lastElement = linkedList.removeLast();

Access elements in the LinkedList:

You can access elements in the LinkedList using methods like first and last.
dart

int firstElement = linkedList.first;
int lastElement = linkedList.last;

Check if the LinkedList is empty:

You can check if the LinkedList is empty using the isEmpty property.
dart

bool isEmpty = linkedList.isEmpty;

Get the length of the LinkedList:

You can get the length of the LinkedList using the length property.
dart

int length = linkedList.length;

Iterate over elements in the LinkedList:

You can iterate over elements in the LinkedList using methods like forEach().
dart

linkedList.forEach((element) {
print(element);
});

Clear the LinkedList:

You can clear all elements from the LinkedList using the clear() method.
dart

linkedList.clear();

These are the basic steps involved in using a LinkedList in Dart. Understanding these steps will help you effectively utilize LinkedLists in your Dart programs.

complete example about:LinkedList 

Here’s a complete Dart code example demonstrating various operations with a LinkedList, along with explanations for each step:

dart

import 'dart:collection';

void main() {
// Step 1: Create a LinkedList instance
LinkedList<int> linkedList = LinkedList();

// Step 2: Add elements to the LinkedList
linkedList.add(1);
linkedList.addLast(2);
linkedList.addFirst(0);

// Step 3: Remove elements from the LinkedList
linkedList.remove(1);
int firstElement = linkedList.removeFirst();
int lastElement = linkedList.removeLast();

// Step 4: Access elements in the LinkedList
int firstElementValue = linkedList.first;
int lastElementValue = linkedList.last;

// Step 5: Check if the LinkedList is empty
bool isEmpty = linkedList.isEmpty;

// Step 6: Get the length of the LinkedList
int length = linkedList.length;

// Step 7: Iterate over elements in the LinkedList
print('Elements of the LinkedList:');
linkedList.forEach((element) {
print(element);
});

// Step 8: Clear the LinkedList
linkedList.clear();

// Step 9: Printing results
print('\nAfter operations:');
print('First Element: $firstElement');
print('Last Element: $lastElement');
print('First Element Value: $firstElementValue');
print('Last Element Value: $lastElementValue');
print('Is the LinkedList empty? $isEmpty');
print('Length of the LinkedList: $length');
}

Explanation for each step:

Create a LinkedList instance:

We create a LinkedList instance named linkedList using the LinkedList class constructor from the dart:collection library.

Add elements to the LinkedList:

We add elements 0, 1, and 2 to the LinkedList using methods like add(), addFirst(), and addLast().

Remove elements from the LinkedList:

We remove the element 1 from the LinkedList using the remove() method. We also remove the first and last elements using removeFirst() and removeLast() methods respectively.

Access elements in the LinkedList:

We access the first and last elements of the LinkedList using the first and last properties.

Check if the LinkedList is empty:

We check if the LinkedList is empty using the isEmpty property.

Get the length of the LinkedList:

We get the length of the LinkedList using the length property.

Iterate over elements in the LinkedList:

We iterate over elements in the LinkedList using the forEach() method and print each element.
Clear the LinkedList:

We clear all elements from the LinkedList using the clear() method.

Printing results:

Finally, we print the results of the operations performed on the LinkedList.

An application about this lesson with explanation

Sure! Let’s create a simple console application in Dart that demonstrates the usage of a LinkedList. This application will allow s to add and remove elements from a LinkedList and perform various operations on it.

Here’s the code:

dart

import 'dart:collection';
import 'dart:io';

void main() {
// Step 1: Create a LinkedList instance
LinkedList<int> linkedList = LinkedList();

// Main application loop
while (true) {
print('\nChoose an option:');
print('1. Add element');
print('2. Remove element');
print('3. Print elements');
print('4. Exit');

// Read input
String choice = stdin.readLineSync() ?? '';
switch (choice) {
case '1':
// Step 2: Add elements to the LinkedList
print('Enter element to add:');
int elementToAdd = int.parse(stdin.readLineSync() ?? '0');
linkedList.add(elementToAdd);
print('Element added: $elementToAdd');
break;
case '2':
// Step 3: Remove elements from the LinkedList
if (linkedList.isEmpty) {
print('The LinkedList is empty.');
} else {
int removedElement = linkedList.removeFirst();
print('Removed element: $removedElement');
}
break;
case '3':
// Step 7: Iterate over elements in the LinkedList and print them
print('\nElements of the LinkedList:');
linkedList.forEach((element) {
print(element);
});
break;
case '4':
// Exit the application
print('Exiting the application.');
return;
default:
print('Invalid option. Please choose again.');
}
}
}

Explanation:

Create a LinkedList instance:

We create a LinkedList instance named linkedList to store integer elements.

Main application loop:

We continuously prompt the for options until they choose to exit the application.

Add elements:

If the chooses option 1, they can add an element to the LinkedList. We read the element from the and add it to the LinkedList using the add() method.

Remove elements:

If the chooses option 2, we remove the first element from the LinkedList using the removeFirst() method.

Print elements:

If the chooses option 3, we iterate over the elements in the LinkedList using the forEach() method and print each element.

Exit the application:

If the chooses option 4, we exit the application.
This application demonstrates a basic interactive console interface for working with a LinkedList in Dart. s can add elements, remove elements, and view the current state of the LinkedList.

Quiz about this leson:20 questions with explanation

Here’s a quiz about the usage of Dart collections including List, Set, Queue, and LinkedList. Each question is followed by an explanation of the correct answer.

1-What Dart library provides the Queue class?

A) dart:core
B) dart:collection
C) dart:math
D) dart:async
Correct Answer: B) dart:collection

Explanation: The Queue class is provided as part of the dart:collection library in Dart.

2-Which of the following collections in Dart is unordered and does not allow duplicate elements?

A) List
B) Set
C) Queue
D) LinkedList
Correct Answer: B) Set

Explanation: Sets in Dart are unordered collections of unique elements. They do not allow duplicates.

3-How do you declare a LinkedList instance in Dart?

A) LinkedList<int> linkedList = LinkedList<int>();
B) LinkedList<int> linkedList = LinkedList();
C) LinkedList<int> linkedList = List<int>();
D) LinkedList<int> linkedList = Set<int>();
Correct Answer: B) LinkedList<int> linkedList = LinkedList();

Explanation: To declare a LinkedList instance, you use the LinkedList class constructor.

4-Which method is used to add an element to the end of a List in Dart?

A) add()
B) insert()
C) addAll()
D) append()
Correct Answer: A) add()

Explanation: The add() method is used to add an element to the end of a List in Dart.

5-Which method is used to remove the last element from a Queue in Dart?

A) removeLast()
B) removeFirst()
C) remove()
D) popLast()
Correct Answer: A) removeLast()

Explanation: The removeLast() method is used to remove the last element from a Queue in Dart.

6-What is the correct way to iterate over elements in a Set in Dart?

A) for (int i = 0; i < set.length; i++) {}
B) for (var element in set) {}
C) for (int i = 0; i < set.size(); i++) {}
D) forEach((element) {})
Correct Answer: B) for (var element in set) {}

Explanation: The correct way to iterate over elements in a Set in Dart is to use a for-in loop.

7-Which method is used to check if a List contains a specific element in Dart?

A) contains()
B) has()
C) exists()
D) includes()
Correct Answer: A) contains()

Explanation: The contains() method is used to check if a List contains a specific element in Dart.

8-Which of the following is NOT a valid method to remove an element from a Set in Dart?

A) remove()
B) discard()
C) delete()
D) clear()
Correct Answer: C) delete()

Explanation: The delete() method is not a valid method to remove an element from a Set in Dart.

9-What does the addAll() method do in Dart?

A) Adds a single element to a collection
B) Adds multiple elements to a collection
C) Adds all elements of one collection to another collection
D) Adds all elements of one collection to the end of another collection
Correct Answer: C) Adds all elements of one collection to another collection

Explanation: The addAll() method in Dart is used to add all elements of one collection to another collection.

10-Which property is used to get the length of a List in Dart?

A) size
B) length
C) count
D) size()
Correct Answer: B) length

Explanation: The length property is used to get the length of a List in Dart.

11-What happens when you try to add a duplicate element to a Set in Dart?

A) The duplicate element is added
B) An error is thrown
C) The duplicate element is ignored
D) The existing element is replaced with the duplicate
Correct Answer: C) The duplicate element is ignored

Explanation: Sets in Dart do not allow duplicate elements, so when you try to add a duplicate element, it is simply ignored.

12-How do you access the first element of a Queue in Dart?

A) queue.first
B) queue[0]
C) queue.elementAt(0)
D) queue.front
Correct Answer: A) queue.first

Explanation: The first property is used to access the first element of a Queue in Dart.

13-Which of the following collections in Dart is ordered and allows duplicate elements?

A) List
B) Set
C) Queue
D) LinkedList
Correct Answer: A) List

Explanation: Lists in Dart are ordered collections that allow duplicate elements.

14-What does the removeWhere() method do in Dart?

A) Removes a specific element from a collection
B) Removes elements that satisfy a condition from a collection
C) Removes all elements from a collection
D) Removes the last element from a collection
Correct Answer: B) Removes elements that satisfy a condition from a collection

Explanation: The removeWhere() method in Dart removes elements that satisfy a condition from a collection.

15-How do you clear all elements from a Queue in Dart?

A) queue.clear()
B) queue.removeAll()
C) queue.removeWhere(() => true)
D) queue.empty()
Correct Answer: A) queue.clear()

Explanation: The clear() method is used to clear all elements from a Queue in Dart.

16-Which method is used to add an element to the beginning of a LinkedList in Dart?

A) addFirst()
B) addLast()
C) add()
D) insertFirst()
Correct Answer: A) addFirst()

Explanation: The addFirst() method is used to add an element to the beginning of a LinkedList in Dart.

17-What does the retainWhere() method do in Dart?

A) Retains a specific element in a collection
B) Retains elements that satisfy a condition in a collection
C) Removes all elements from a collection
D) Removes the last element from a collection
Correct Answer: B) Retains elements that satisfy a condition in a collection

Explanation: The retainWhere() method in Dart retains elements that satisfy a condition in a collection.

18-Which of the following is NOT a method to remove an element from a LinkedList in Dart?

A) remove()
B) removeFirst()
C) removeLast()
D) pop()
Correct Answer: D) pop()

Explanation: The pop() method is not a method to remove an element from a LinkedList in Dart.

19-What does the isEmpty property return in Dart for a Set that contains elements?

A) true
B) false
C) null
D) An error is thrown
Correct Answer: B) false

Explanation: The isEmpty property returns false for a Set that contains elements.

20-Which property is used to get the first element of a LinkedList in Dart?

A) first
B) front
C) head
D) start
Correct Answer: A) first

Explanation: The first property is used to get the first element of a LinkedList in Dart.