How to Iterate Over Keys in a Map in Dart - Step by Step Examples

How to Iterate Over Keys in a Map in Dart ?

Answer

To iterate over keys in a map in Dart, you can use the keys property along with a for loop or a forEach method. This allows you to access each key in the map.

✐ Examples

1 Iterating Over Keys Using for Loop

We can iterate over keys in a map in Dart using a for loop with the keys property, which provides a convenient syntax for iterating over all keys in 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 keys property to get an iterable of the keys in the map.
We iterate over the keys using a for loop, accessing each key directly from the iterable.
We print each key to the console using the print function to verify that we are iterating over all keys.

Dart Program

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

    // Iterate over keys using for loop
    for (String key in myMap.keys) {
        print(key);
    }
}

Output

one
two
three

2 Iterating Over Keys Using forEach Method

We can iterate over keys in a map in Dart using the forEach method, which provides a flexible way to access each key in 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 forEach method to iterate over the key-value pairs in the map.
In the callback function passed to forEach, we access each key.
We print each key to the console using the print function to verify that we are iterating over all keys.

Dart Program

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

    // Iterate over keys using forEach method
    myMap.forEach((key, value) {
        print(key);
    });
}

Output

one
two
three

3 Iterating Over Keys Using MapEntry

We can iterate over keys in a map in Dart using the MapEntry class, which provides a convenient way to access both keys and values.

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 entries property to get an iterable of the map's entries, which are instances of the MapEntry class.
We iterate over the entries using a for loop, accessing each key through the key property of MapEntry.
We print each key to the console using the print function to verify that we are iterating over all keys.

Dart Program

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

    // Iterate over keys using MapEntry
    for (MapEntry<String, int> entry in myMap.entries) {
        print(entry.key);
    }
}

Output

one
two
three

Summary

In this tutorial, we learned How to Iterate Over Keys in a Map in Dart language with well detailed examples.

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How to Iterate Over Keys in a Map in Dart - Step by Step Examples