How to Sort List by Date in Dart/Flutter

Sorting lists by date is a common requirement in many applications. In this blog post, we will explore how to sort a list by date in Dart/Flutter.

Table of Contents

Introduction to Sorting in Dart/Flutter

Dart provides various ways to sort lists, including the use of the `sort` method. However, sorting a list by date requires a custom comparison function. This function compares two dates and returns an integer value indicating their order.

Sorting a List by Date

To sort a list by date in Dart/Flutter, you can use the `sort` method and provide a custom comparison function. Here’s an example:

“`dart

void main() {

List dates = [

DateTime(2022, 12, 15),

DateTime(2022, 12, 10),

DateTime(2022, 12, 20),

];

dates.sort((a, b) => a.compareTo(b));

print(dates);

}

“`

In this example, the `sort` method is used to sort the list of dates. The `compareTo` method is used as the comparison function, which compares two dates and returns an integer value indicating their order.

Sorting a List of Objects by Date

If you have a list of objects and each object has a date property, you can sort the list by date as follows:

“`dart

class Item {

String name;

DateTime date;

Item({required this.name, required this.date});

}

void main() {

List items = [

Item(name: ‘Item 1’, date: DateTime(2022, 12, 15)),

Item(name: ‘Item 2’, date: DateTime(2022, 12, 10)),

Item(name: ‘Item 3’, date: DateTime(2022, 12, 20)),

];

items.sort((a, b) => a.date.compareTo(b.date));

print(items);

}

“`

In this example, the `sort` method is used to sort the list of items by their date property.

Descending Order

To sort a list in descending order, you can modify the comparison function to return the opposite value:

“`dart

void main() {

List dates = [

DateTime(2022, 12, 15),

DateTime(2022, 12, 10),

DateTime(2022, 12, 20),

];

dates.sort((a, b) => b.compareTo(a));

print(dates);

}

“`

In this example, the list is sorted in descending order.

Conclusion

Sorting a list by date in Dart/Flutter can be achieved using the `sort` method and a custom comparison function. By using the `compareTo` method, you can compare two dates and return an integer value indicating their order. You can also sort a list of objects by their date property.