1. Dart
  2. Collections in Dart
  3. Dart Practice Questions in Collections

 Questions for Practice on Dart Collections

  1. Create a List of integers from 1 to 10 and print all the elements.
  2. Write a program to add three different fruits to a List and print the List.
  3. Demonstrate how to access the third element in a List of strings.
  4. Create a List of numbers and remove the number 5. Print the updated List.
  5. Iterate over a List of integers and print only those that are even using a forEach method.
  6. Create a Set of strings containing names, add a duplicate name, and print the Set.
  7. Write a program to check if a Set contains a specific name.
  8. Create a Map to store student names and their grades, then print each student's name and grade.
  9. Filter a List of integers to only include numbers greater than 5 and print the result.
  10. Create a Map of countries and their capitals, then retrieve and print the capital of a specified country.
  11. Write a program to find the intersection of two Sets and print the result.
  12. Use the where method to filter a List of strings to only include names starting with 'A'.
  13. Create a List of mixed data types (int, String) and print only the integers.
  14. Write a program that combines two Lists into a Set to remove duplicates.
  15. Demonstrate how to clear all elements from a Map and check if it is empty.

Solutions with Code Explanation

 

1. Create a List of integers from 1 to 10 and print all the elements.

 

void main() {
  List<int> numbers = List.generate(10, (index) => index + 1);
  print(numbers); // Output: [1, 2, 3, 4, 5, 6, 7, 8, 9, 10] }

This code uses List.generate to create a list of integers from 1 to 10.

2. Write a program to add three different fruits to a List and print the List.

void main() {
  List<String> fruits = [];
  fruits.add('Apple');
  fruits.add('Banana');
  fruits.add('Cherry');
  print(fruits); // Output: [Apple, Banana, Cherry] }

Here, we initialize an empty list and use the add method to insert fruits.

3. Demonstrate how to access the third element in a List of strings.

void main() {
  List<String> fruits = ['Apple', 'Banana', 'Cherry', 'Date'];
  print(fruits[2]); // Output: Cherry }

Lists are zero-indexed, so the third element is at index 2.

4. Create a List of numbers and remove the number 5. Print the updated List.

void main() {
  List<int> numbers = [1, 2, 3, 4, 5, 6];
  numbers.remove(5);
  print(numbers); // Output: [1, 2, 3, 4, 6] 
  }

The remove method deletes the specified element from the List.

5. Iterate over a List of integers and print only those that are even using a forEach method.

void main() {
  List<int> numbers = [1, 2, 3, 4, 5, 6];
  numbers.forEach((number) {
    if (number.isEven) {
      print(number); // Output: 2, 4, 6     
      }
  });
}

The forEach method applies a function to each element in the List.

6. Create a Set of strings containing names, add a duplicate name, and print the Set.

void main() {
  Set<String> names = {'Alice', 'Bob', 'Charlie'};
  names.add('Alice'); // Adding a duplicate   
  print(names); // Output: {Alice, Bob, Charlie} 
  }

Sets automatically ignore duplicate entries.

7. Write a program to check if a Set contains a specific name.

void main() {
  Set<String> names = {'Alice', 'Bob', 'Charlie'};
  print(names.contains('Bob')); // Output: true }

The contains method checks for the presence of an element in the Set.

8. Create a Map to store student names and their grades, then print each student's name and grade.

void main() {
  Map<String, int> grades = {
    'Alice': 90,
    'Bob': 85,
    'Charlie': 88,
  };

  grades.forEach((name, grade) {
    print('$name: $grade'); // Output: Alice: 90, Bob: 85, Charlie: 88   });
}

The forEach method is used to iterate over key-value pairs in the Map.

9. Filter a List of integers to only include numbers greater than 5 and print the result.

 

void main() {
  List<int> numbers = [1, 2, 3, 6, 8, 5];
  var filtered = numbers.where((number) => number > 5);
  print(filtered.toList()); // Output: [6, 8] }

The where method filters the list based on the specified condition.

10. Create a Map of countries and their capitals, then retrieve and print the capital of a specified country.

 

void main() {
  Map<String, String> capitals = {
    'USA': 'Washington, D.C.',
    'France': 'Paris',
    'Japan': 'Tokyo',
  };

  print(capitals['France']); // Output: Paris }

You access the value by using the key in the Map.

11. Write a program to find the intersection of two Sets and print the result.

void main() {
  Set<int> setA = {1, 2, 3, 4};
  Set<int> setB = {3, 4, 5, 6};
  
  var intersection = setA.intersection(setB);
  print(intersection); // Output: {3, 4} }

The intersection method returns a new Set containing common elements.

12. Use the where method to filter a List of strings to only include names starting with 'A'.

void main() {
  List<String> names = ['Alice', 'Bob', 'Annie', 'Charlie'];
  var filteredNames = names.where((name) => name.startsWith('A'));
  print(filteredNames.toList()); // Output: [Alice, Annie] }

The where method filters names based on the starting character.

13. Create a List of mixed data types (int, String) and print only the integers.

void main() {
  List<dynamic> mixedList = [1, 'two', 3, 'four', 5];
  var integers = mixedList.where((item) => item is int);
  print(integers.toList()); // Output: [1, 3, 5] }

The is operator checks the type of each element.

14. Write a program that combines two Lists into a Set to remove duplicates.

void main() {
  List<int> list1 = [1, 2, 3, 4];
  List<int> list2 = [3, 4, 5, 6];
  
  Set<int> combinedSet = {...list1, ...list2};
  print(combinedSet); // Output: {1, 2, 3, 4, 5, 6} 
  }

Using the spread operator combines two Lists into a Set, removing duplicates.

15. Demonstrate how to clear all elements from a Map and check if it is empty.

void main() {
  Map<String, int> grades = {
    'Alice': 90,
    'Bob': 85,
  };

  grades.clear();
  print(grades.isEmpty); // Output: true 
 }

The clear method removes all entries from the Map, and isEmpty checks if it’s empty.

These questions and solutions provide a comprehensive overview of working with collections in Dart, covering lists, sets, maps, and various operations you can perform on them.

Previous
Next