Dart: How to remove specific Entries from a Map

In Dart, you can remove key/value pairs from a given map by using one of the following methods:

• remove(): Removes the entry that associated with the provided key. No error will occur even if the provided key doesn’t exist.
• removeWhere(): Removes all entries that satisfy the given conditions.

For more clarity, see the examples below.Advertisements

Example 1: Using remove()

This code snippet removes the entries that contain keys: age, occupation, hometown.

// main.dart
Map<String, dynamic> person = {
  'name': 'John Doe',
  'age': 39,
  'occupation': 'Thief',
  'hometown': 'Unknown',
  'isMarried': false
};

void main() {
  person.remove('age');
  person.remove('occupation');
  person.remove('hometown');
  print(person);
}

Output:

name: John Doe, isMarried: false}

Example 2: Using removeWhere()

AdvertisementsThe following code removes entries with values of null or a whose key is secret:

// main.dart
Map<String, dynamic> project = {
  'title': 'KindaCode.com: A Programming Website',
  'age': 5,
  'language': 'English',
  'technologies': 'Unknown',
  'traffic': null,
  'contact': null,
  'secret': 'Flying pan'
};

void main() {
  project.removeWhere((key, value) => value == null || key == 'secret');
  print(project);
}

Output:

{title: KindaCode.com: A Programming Website, age: 5, language: English, technologies: Unknown}

Futher Reading

• Dart: Convert Timestamp to DateTime and vice versa
• Using Cascade Notation in Dart and Flutter
• Dart & Flutter: Get the Index of a Specific Element in a List
• Dart: Capitalize the First Letter of Each Word in a String
• Dart: Convert Map to Query String and vice versa

You can also take a tour around our Flutter topic page and Dart topic page to see the latest tutorials and examples.Advertisements