This is a repository of Dart list manipulation methods created for easy reference. It contains a comprehensive list of methods that can be used to manipulate lists in Dart.
These methods are useful for anyone who works with lists frequently and wants to quickly look up available options. The repository serves as a handy reference guide, allowing developers to easily find the function they need without having to search for it elsewhere.
By structuring these methods in a single location, it makes it easier to keep track of them and utilize them effectively in projects.
A brief explanation of each function is provided along with a dart code example. Incase of any issues, please raise an issue in the repository and I will get back to you as soon as possible.
A Youtube playlist with some of the methods explained is available here.
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All code examples are available in the main.dart file.
The code examples have been tested on Dart 2.19.2
Run code using the following command:
dart main.dart
The following methods are covered:
add: adds an element to the end of a listinsert: inserts an element at a specific index in a listaddAll: adds multiple elements to the end of a listremove: removes the first occurrence of an element from a listremoveAt: removes an element at a specific index in a listremoveLast: removes the last element from a listremoveRange: removes a range of elements from a listclear: removes all elements from a listshuffle: Randomly shuffles the elements in the list.sublist: Returns a new list containing a specified range of elements from an existing list.sort: Sorts the elements in the list.map: Applies a function to each element in the list and returns a new list with the results.firstWhere: Returns the first element that satisfies a specified condition.lastWhere: Returns the last element that satisfies a specified condition.where: Returns a new list containing only the elements that satisfy a specified condition.whereType: Returns a new list containing only the elements that are of a specified type.forEach: Executes a function for each element in the list.fold: Accumulates a single value by applying a function to each element in the list.reduce: Reduces the list to a single value by applying a function to each element.any: Checks if at least one element in the list satisfies a specified condition.every: Checks if all elements in the list satisfy a specified condition.expand: Expand keyword applies a function to each element in the list and returns a new list with the results.
The add function adds an element to the end of a list.
List<int> oddNumbers = [1, 3, 5];
oddNumbers.add(7);
print(oddNumbers); // [1, 3, 5, 7]The insert function inserts an element at a specific index in a list.
List<int> oddNumbers = [1, 3, 5];
int position = 1;
oddNumbers.insert(position, 2);
print(oddNumbers); // [1, 2, 3, 5] 2, 3, 5]The addAll function adds multiple elements to the end of a list. You can achieve the same results using other alternatives as shown below.
List<int> oddNumbers = [1, 3, 5];
List<int> evenNumbers = [2, 4, 6];
// add all keyword
oddNumbers.addAll(evenNumbers);
print(oddNumbers); // [1, 3, 5, 2, 4, 6]
// alternative method using + operator
List<int> numbers = oddNumbers + evenNumbers;
print(numbers); // [1, 3, 5, 2, 4, 6]
// alternative method using spread operator
List<int> allNumbers = [...oddNumbers, ...evenNumbers];
print(allNumbers); // [1, 3, 5, 2, 4, 6]The remove function removes the first occurrence of an element from a list.
List<int> oddNumbers = [1, 3, 5];
oddNumbers.remove(3);
print(oddNumbers); // [1, 5]The removeAt function removes an element at a specific index in a list.
List<int> oddNumbers = [1, 3, 5];
int position = 1;
oddNumbers.removeAt(position);
print(oddNumbers); // [1, 5]The removeLast function removes the last element from a list.
List<int> oddNumbers = [1, 3, 5];
oddNumbers.removeLast();
print(oddNumbers); // [1, 3]The removeRange function removes a range of elements from a list.
List<int> oddNumbers = [1, 3, 5, 7];
int start = 0;
int end = 1;
oddNumbers.removeRange(start, end);
print(oddNumbers); // [5, 7]The clear function removes all elements from a list.
List<int> oddNumbers = [1, 3, 5];
oddNumbers.clear();
print(oddNumbers); // []
// an alternative is to assign an empty list to the variable
oddNumbers = [];
print(oddNumbers); // []The shuffle function randomly shuffles the elements in the list.
List<int> oddNumbers = [1, 3, 5];
oddNumbers.shuffle();
print(oddNumbers); // [5, 1, 3]The sublist function returns a new list containing a specified range of elements from an existing list.
List<int> oddNumbers = [1, 3, 5, 7];
int start = 1;
int end = 3;
List<int> subList = oddNumbers.sublist(start, end);
print(subList); // [3, 5]The sort function sorts the elements in the list. You can apply sorting in ascending or descending order. You can also sort list of objects based on their properties.
List<int> oddNumbers = [1, 5, 3, 7];
oddNumbers.sort();
print(oddNumbers); // [1, 3, 5, 7]
// sort in descending order
oddNumbers.sort((a, b) => b.compareTo(a));
print(oddNumbers); // [7, 5, 3, 1]
// sort list of objects based on their properties
List<Fruit> fruits = [
Fruit(id: 1, name: 'banana', color: 'yellow'),
Fruit(id: 2, name: 'apple', color: 'red'),
Fruit(id: 3, name: 'orange', color: 'orange'),
];
fruits.sort((a, b) => a.name.compareTo(b.name));
print("Sort by name ascending order: $fruits");
// Sort by name ascending order: [Fruit{id: 2, name: apple, color: red}, Fruit{id: 1, name: banana, color: yellow}, Fruit{id: 3, name: orange, color: orange}]
fruits.sort((a, b) => a.id.compareTo(b.id));
print("Sort by id ascending order: $fruits");
// Sort by id ascending order: [Fruit{id: 1, name: banana, color: yellow}, Fruit{id: 2, name: apple, color: red}, Fruit{id: 3, name: orange, color: orange}]
fruits.sort((a, b) => b.id.compareTo(a.id));
print("Sort by id descending order: $fruits");
// Sort by id descending order: [Fruit{id: 3, name: orange, color: orange}, Fruit{id: 2, name: apple, color: red}, Fruit{id: 1, name: banana, color: yellow}]The map function applies a function to each element in the list and returns a new list with the results.
List<int> oddNumbers = [1, 3, 5];
List<int> evenNumbers = oddNumbers.map((number) => number * 2).toList();
print(evenNumbers); // [2, 6, 10]
List<Fruit> fruits = [
Fruit(id: 1, name: 'banana', color: 'yellow'),
Fruit(id: 2, name: 'apple', color: 'red'),
Fruit(id: 3, name: 'orange', color: 'orange'),
];
List<String> fruitNames = fruits.map((fruit) => fruit.name).toList();
print(fruitNames); // [banana, apple, orange]The firstWhere function returns the first element in the list that matches a given condition.
List<int> oddNumbers = [1, 3, 5];
int firstOddNumber = oddNumbers.firstWhere((number) => number > 2);
print(firstOddNumber); // 3
List<Fruit> fruits = [
Fruit(id: 1, name: 'banana', color: 'yellow'),
Fruit(id: 2, name: 'apple', color: 'red'),
Fruit(id: 3, name: 'orange', color: 'orange'),
];
bool isFruitApple(Fruit fruit){
return fruit.name == 'apple';
}
Fruit fruit;
fruit = fruits.firstWhere(isFruitApple);
print(fruit); // Fruit{id: 2, name: apple, color: red}
fruit = fruits.firstWhere((fruit) => fruit.name == 'apple');
print(fruit); // Fruit{id: 2, name: apple, color: red}The lastWhere function returns the last element in the list that matches a given condition.
List<int> oddNumbers = [1, 3, 5];
int lastOddNumber = oddNumbers.lastWhere((number) => number > 2);
print(lastOddNumber); // 5
List<Fruit> fruits = [
Fruit(id: 1, name: 'banana', color: 'yellow'),
Fruit(id: 2, name: 'apple', color: 'green'),
Fruit(id: 3, name: 'mango', color: 'green'),
];
bool isFruitColorGreen(Fruit fruit){
return fruit.color == 'green';
}
Fruit fruit;
fruit = fruits.lastWhere(isFruitColorGreen);
print(fruit); // Fruit{id: 3, name: mango, color: green}
fruit = fruits.lastWhere((fruit) => fruit.color == 'green');
print(fruit); // Fruit{id: 3, name: mango, color: green}The where function returns a new list containing all elements that match a given condition.
List<int> oddNumbers = [1, 3, 5];
List<int> oddNumbersGreaterThan2 = oddNumbers.where((number) => number > 2).toList();
print(oddNumbersGreaterThan2); // [3, 5]
List<Fruit> fruits = [
Fruit(id: 1, name: 'banana', color: 'yellow'),
Fruit(id: 2, name: 'apple', color: 'red'),
Fruit(id: 3, name: 'orange', color: 'orange'),
Fruit(id: 4, name: 'peach', color: 'orange'),
];
bool isColorOrange(Fruit fruit){
return fruit.color == 'orange';
}
List<Fruit> fruitsWithColorOrange = [];
fruitsWithColorOrange = fruits.where(isColorOrange).toList();
print(fruitsWithColorOrange); // [Fruit{id: 3, name: orange, color: orange}, Fruit{id: 4, name: peach, color: orange}]
fruitsWithColorOrange = fruits.where((fruit) => fruit.color == 'orange').toList();
print(fruitsWithColorOrange); // [Fruit{id: 3, name: orange, color: orange}, Fruit{id: 4, name: peach, color: orange}]The whereType function returns a new list containing all elements that match a given type.
List<dynamic> list = [1, 'two', 3, 'four', 5];
List<int> numbers = list.whereType<int>().toList();
print(numbers); // [1, 3, 5]The forEach function applies a function to each element in the list.
List<int> oddNumbers = [1, 3, 5];
oddNumbers.forEach((number) => print(number));
// 1
// 3
// 5
List<Fruit> fruits = [
Fruit(id: 1, name: 'banana', color: 'yellow'),
Fruit(id: 2, name: 'apple', color: 'red'),
Fruit(id: 3, name: 'orange', color: 'orange'),
];
fruits.forEach((fruit) {
print(fruit.name.toUpperCase());
});
// BANANA
// APPLE
// ORANGEThe fold function combines all elements in the list into a single value by repeatedly applying a function.
int initialValue = 0;
List<int> oddNumbers = [1, 3, 5];
int sum = oddNumbers.fold(initialValue, (previousValue, element) => previousValue + element);
print(sum); // 9
List<Fruit> fruits = [
Fruit(id: 1, name: 'banana', color: 'yellow'),
Fruit(id: 2, name: 'apple', color: 'red'),
Fruit(id: 3, name: 'orange', color: 'orange'),
];
String fruitNames = fruits.fold('', (previousValue, element) => previousValue + element.name + ', ');
print(fruitNames); // banana, apple, orange,
List<Cart> cartItems = [
Cart(id: 1, title: 'banana', quantity: 3, unitPrice: 10),
Cart(id: 2, title: 'apple', quantity: 2, unitPrice: 20),
Cart(id: 3, title: 'orange', quantity: 5, unitPrice: 30),
];
double initialUnitPrice = 0.0;
double total = cartItems.fold(initialUnitPrice, (previousValue, element) => previousValue + (element.quantity * element.unitPrice));
print(total); // 220.0The reduce function combines all elements in the list into a single value by repeatedly applying a function.
The difference between fold and reduce is that fold takes an initial value as a parameter, while reduce does not. Reduce uses the first element in the list as the initial value.
List<int> oddNumbers = [1, 3, 5];
int sum = oddNumbers.reduce((value, element) => value + element);
print(sum); // 9
List<Fruit> fruits = [
Fruit(id: 1, name: 'banana', color: 'yellow'),
Fruit(id: 2, name: 'apple', color: 'red'),
Fruit(id: 3, name: 'orange', color: 'blue'),
];
String fruitNames = fruits.reduce((value, element) => value..name += ', ${element.name}').name;
print(fruitNames); // banana, apple, orangeThe every function returns true if all elements in the list match a given condition.
List<int> oddNumbers = [1, 3, 5];
bool areAllOddNumbersGreaterThan2 = oddNumbers.every((number) => number > 2);
print(areAllOddNumbersGreaterThan2); // false
List<Fruit> fruits = [
Fruit(id: 1, name: 'banana', color: 'yellow'),
Fruit(id: 2, name: 'apple', color: 'red'),
Fruit(id: 3, name: 'orange', color: 'orange'),
];
bool areAllFruitsOrange = fruits.every((fruit) => fruit.color == 'orange');
print(areAllFruitsOrange); // The any function returns true if at least one element in the list matches a given condition.
List<int> oddNumbers = [1, 3, 5];
bool isAnyOddNumberGreaterThan2 = oddNumbers.any((number) => number > 2);
print(isAnyOddNumberGreaterThan2); // true
List<Fruit> fruits = [
Fruit(id: 1, name: 'banana', color: 'yellow'),
Fruit(id: 2, name: 'apple', color: 'red'),
Fruit(id: 3, name: 'orange', color: 'orange'),
];
bool isAnyFruitOrange = fruits.any((fruit) => fruit.color == 'orange');
print(isAnyFruitOrange); // trueThe expand function expands each element of a list into zero or more elements.
List<int> oddNumbers = [1, 3, 5];
List<int> oddNumbersDoubled = oddNumbers.expand((number) => [number, number * 2]).toList();
print(oddNumbersDoubled); // [1, 2, 3, 6, 5, 10]
List<Fruit> fruits = [
Fruit(id: 1, name: 'banana', color: 'yellow'),
Fruit(id: 2, name: 'apple', color: 'red'),
Fruit(id: 3, name: 'orange', color: 'orange'),
];
List<String> fruitNames = fruits.expand((fruit) => [fruit.name, fruit.color]).toList();
print(fruitNames); // [banana, yellow, apple, red, orange, orange]
List<Cart> cartItems = [
Cart(id: 1, title: 'banana', quantity: 3, unitPrice: 10),
Cart(id: 2, title: 'apple', quantity: 2, unitPrice: 20),
Cart(id: 3, title: 'orange', quantity: 5, unitPrice: 30),
];
List<String> cartItemsWithTotal = cartItems.expand((cartItem) => [cartItem.title, (cartItem.quantity * cartItem.unitPrice).toString()]).toList();
print(cartItemsWithTotal); // [banana, 30, apple, 40, orange, 150]
// you can use it for more complex cases here are some examples
List<List<int>> listOfLists = [[1, 2], [3, 4], [5, 6]];
List<int> flattenedList = listOfLists.expand((list) => list).toList();
print(flattenedList); // [1, 2, 3, 4, 5, 6]
List<Product> products = [
Product(id: 1, title: 'banana', currencyPrices: [Price(currency: "USD", value: 4.00), Price(currency: "EUR", value: 3.00), Price(currency: "BTC", value: 0.002)]),
Product(id: 2, title: 'apple', currencyPrices: [Price(currency: "USD", value: 5.00), Price(currency: "EUR", value: 4.00), Price(currency: "BTC", value: 0.003)]),
Product(id: 3, title: 'orange', currencyPrices: [Price(currency: "USD", value: 6.00), Price(currency: "EUR", value: 5.00), Price(currency: "BTC", value: 0.004)]),
];
// get list of all product prices where currency is BTC
List<Price> productBTCPrices = products.expand((product) => product.currencyPrices.where((price) => price.currency == "BTC")).toList();
print(productBTCPrices);
// [Price(currency: BTC, value: 0.002), Price(currency: BTC, value: 0.003), Price(currency: BTC, value: 0.004)]
// list of all product prices
List<Price> allProductPrices = products.expand((product) => product.currencyPrices).toList();
print(allProductPrices);
// [Price(currency: USD, value: 4.0), Price(currency: EUR, value: 3.0), Price(currency: BTC, value: 0.002), Price(currency: USD, value: 5.0), Price(currency: EUR, value: 4.0), Price(currency: BTC, value: 0.003), Price(currency: USD, value: 6.0), Price(currency: EUR, value: 5.0), Price(currency: BTC, value: 0.004)]
// list of all products with their respective currency prices
List<String> productPrices = products.expand((product) => product.currencyPrices.map((price) => '${product.title} price in ${price.currency} is ${price.value}')).toList();
print(productPrices);
// [banana price in USD is 4.0, banana price in EUR is 3.0, banana price in BTC is 0.002, apple price in USD is 5.0, apple price in EUR is 4.0, apple price in BTC is 0.003, orange price in USD is 6.0, orange price in EUR is 5.0, orange price in BTC is 0.004]Pull requests are welcome. For major changes, please open an issue first to discuss what you would like to change.
Please make sure you test as appropriately.