How to Merge Two Maps in Dart - Step by Step Examples

How to Merge Two Maps in Dart ?

Answer

To merge two maps in Dart, you can use the addAll() method to add key-value pairs from one map to another. This method provides a straightforward way to combine the contents of two maps.

✐ Examples

1 Merging Two Maps Using addAll() Method

We can merge two maps in Dart using the addAll() method, which adds all key-value pairs from one map to another.

For example,

We start by declaring and initializing two maps named map1 and map2 with some key-value pairs. In this example, both maps have string keys and integer values.
We use the addAll() method to add all key-value pairs from map2 to map1.
We print the merged map to the console using the print function to verify the merge.

Dart Program

void main() {
    // Declare and initialize two maps
    Map<String, int> map1 = {'one': 1, 'two': 2};
    Map<String, int> map2 = {'three': 3, 'four': 4};

    // Merge map2 into map1
    map1.addAll(map2);

    // Print the merged map
    print('Merged Map: $map1');
}

Output

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

2 Merging Two Maps with Overlapping Keys Using addAll() Method

We can merge two maps in Dart and handle overlapping keys by using the addAll() method, which updates the values for overlapping keys.

For example,

We start by declaring and initializing two maps named map1 and map2 with some key-value pairs. In this example, both maps have string keys and integer values, and there is an overlapping key.
We use the addAll() method to add all key-value pairs from map2 to map1.
We print the merged map to the console using the print function to verify the merge.

Dart Program

void main() {
    // Declare and initialize two maps with overlapping keys
    Map<String, int> map1 = {'one': 1, 'two': 2};
    Map<String, int> map2 = {'two': 22, 'three': 3};

    // Merge map2 into map1, updating values for overlapping keys
    map1.addAll(map2);

    // Print the merged map
    print('Merged Map: $map1');
}

Output

Merged Map: {one: 1, two: 22, three: 3}

3 Merging Two Maps Using Spread Operator

We can also merge two maps in Dart using the spread operator, which provides a concise way to combine the contents of two maps.

For example,

We start by declaring and initializing two maps named map1 and map2 with some key-value pairs. In this example, both maps have string keys and integer values.
We use the spread operator to create a new map that combines the contents of map1 and map2.
We print the merged map to the console using the print function to verify the merge.

Dart Program

void main() {
    // Declare and initialize two maps
    Map<String, int> map1 = {'one': 1, 'two': 2};
    Map<String, int> map2 = {'three': 3, 'four': 4};

    // Merge the maps using the spread operator
    Map<String, int> mergedMap = {...map1, ...map2};

    // Print the merged map
    print('Merged Map: $mergedMap');
}

Output

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

Summary

In this tutorial, we learned How to Merge Two Maps in Dart language with well detailed examples.

◀ Previous Next ▶

Dart Tutorials

Dart How-Tos

How to Merge Two Maps in Dart - Step by Step Examples