How to Add a Key-Value Pair to a Map in Dart

How to Add a Key-Value Pair to a Map in Dart ?

Answer

To add a key-value pair to a map in Dart, you can use the subscript operator or the addAll method.

✐ Examples

1 Adding a Key-Value Pair Using Subscript Operator

We can add a key-value pair to a map in Dart using the subscript operator, which adds an element with a specific key and value to the map.

For example,

We start by declaring and initializing a map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We use the subscript operator to add a new key-value pair to the map. The subscript operator allows us to specify the key and assign a value to it.
We print the updated map to the console using the print function.

Dart Program

void main() {
    // Declare and initialize a map
    Map<String, int> myMap = {
        'one': 1,
        'two': 2,
        'three': 3
    };

    // Add a key-value pair using subscript operator
    myMap['four'] = 4;

    // Print the updated map
    print(myMap);
}

Output

{one: 1, two: 2, three: 3, four: 4}

2 Adding a Key-Value Pair Using addAll Method

We can add a key-value pair to a map in Dart using the addAll method, which adds all key-value pairs from another map.

For example,

We start by declaring and initializing a map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We use the addAll method to add new key-value pairs to the map. The addAll method takes another map containing the key-value pairs to be added.
We print the updated map to the console using the print function.

Dart Program

void main() {
    // Declare and initialize a map
    Map<String, int> myMap = {
        'one': 1,
        'two': 2,
        'three': 3
    };

    // Add a key-value pair using addAll method
    myMap.addAll({'four': 4});

    // Print the updated map
    print(myMap);
}

Output

{one: 1, two: 2, three: 3, four: 4}

3 Adding Multiple Key-Value Pairs Using addAll Method

We can add multiple key-value pairs to a map in Dart using the addAll method, which adds all key-value pairs from another map.

For example,

We start by declaring and initializing a map named myMap with some key-value pairs. In this example, the map has string keys and integer values.
We use the addAll method to add multiple new key-value pairs to the map. The addAll method takes another map containing the key-value pairs to be added.
We print the updated map to the console using the print function.

Dart Program

void main() {
    // Declare and initialize a map
    Map<String, int> myMap = {
        'one': 1,
        'two': 2,
        'three': 3
    };

    // Add multiple key-value pairs using addAll method
    myMap.addAll({'four': 4, 'five': 5});

    // Print the updated map
    print(myMap);
}

Output

{one: 1, two: 2, three: 3, four: 4, five: 5}

Summary

In this tutorial, we learned How to Add a Key-Value Pair to a Map in Dart language with well detailed examples.

◀ Previous Next ▶

Dart Tutorials

Dart How-Tos

How to Add a Key-Value Pair to a Map in Dart