In this guide, we will learn top 10 the array utility methods that are used in the dart. We will demonstrate it with the help of the examples.
1. map():
Produces a new list after transforming each element in a given list
void main() {
var name = ['Flutter', 'Dart', 'Deno', 'Firebase'];
var result = name.map((e) => 'I love $e');
print(result);
}
The Output will be (I love Flutter, I love Dart, I love Deno, I love Firebase)
2. contains()
Checks to confirm that the given element is in the list
void main() {
var name = ['Flutter', 'Dart', 'Deno', 'Firebase'];
var result = name.contains('Deno');
print(result);
}
The Output will be true
3. sort()
Orders the elements in a list based on the provided ordering function
void main() {
List<String> name = [
'sagar',
'koju',
'sanam',
'keshav',
'pancha',
'mobile',
'flutter',
'deno',
'dart',
];
name.sort();
print(name);
}
The Output will be [dart, deno, flutter, keshav, koju, mobile, pancha, sagar, sanam]
4. forEach()
Runs a function on each element in the list
void main() {
List<String> name = ['sagar', 'koju', 'is', 'flutter', 'developer'];
name.forEach((e) => print(e));
}
The Output will be sagar koju is flutter developer
5. reduce(), fold()
Compresses the elements of a list to a single value, using a given function
void main() {
List<int> numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
List<int> numbers1 = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11];
int sum = numbers.fold(0, (a, b) => a + b);
int sum1 = numbers1.reduce((a, b) => a + b);
print(sum);
print(sum1);
}
The Output will be 55 and 66
6. every()
Confirms that every element satisfies the test
void main() {
final checkage = name.every((e) => e.age >= 5);
print(checkage.toString());
}
class Person {
final String name;
final int age;
Person(this.name, this.age);
}
List<Person> name = [
Person('A', 10),
Person('B', 20),
Person('C', 30),
Person('D', 40),
Person('E', 50),
Person('F', 60),
];
The Output will be true
7. where(), firstWhere(), singleWhere()
Returns a collection of elements that satisfy a test.
firstWhere()
returns the first match in the list,
singleWhere()
returns the first match provided there is exactly one match.
void main() {
List<int> numeber = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
numeber.where((e) => e % 2 == 0).forEach((e) => print(e));
final s = numeber.firstWhere((element) => element.toString().contains('5'));
final ss = numeber.singleWhere((element) => element == 4);
print(s);
print(ss);
}
The Output will be 2 4 6 8 10 and 5 and 4
8. take(), skip()
Returns a collection while including or skipping elements
void main() {
List<String> names = [
'Dell',
'MAC',
'OS',
];
var data = names.skip(2).toList();
var data1 = names.take(2).toList();
print(data);
print(data1);
}
The output will be [OS] and [Dell, MAC]
9. List.from()
Creates a new list from the given collection
void main() { List<int> numbers = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]; var data = List.from(numbers); print(data); }
The output will be [1, 2, 3, 4, 5, 6, 7, 8, 9, 10]
10. expand()
Expands each element into zero or more elements
void main() {
var input = [1, 2, 3, 4, 5];
var data = input.expand((i) => [i, i]).toList();
print(data);
}
The output will be [1, 1, 2, 2, 3, 3, 4, 4, 5, 5]
Thank you for reading the Guide about Top 10 Array utility methods that We should know in Dart