How to Check if Two Maps are Equal in Dart

How to Check if Two Maps are Equal in Dart ?

Answer

To check if two maps are equal in Dart, you can compare their lengths and use the equality operator (==) to compare the key-value pairs. This method provides a straightforward way to determine if two maps contain the same elements.

✐ Examples

1 Checking Equality of Two Maps Using Equality Operator

We can check if two maps are equal in Dart by comparing their lengths and using the equality operator to compare their key-value pairs.

For example,

We start by declaring and initializing two maps named map1 and map2 with some key-value pairs. In this example, the maps have string keys and integer values.
We use an if statement to compare the lengths of map1 and map2. If their lengths are equal, we use the equality operator (==) to check if the key-value pairs in both maps are equal.
We print the result to the console using the print function to indicate whether the maps are equal or not.

Dart Program

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

    // Check if the maps are equal
    if (map1.length == map2.length && map1 == map2) {
        print('Maps are equal');
    } else {
        print('Maps are not equal');
    }
}

Output

Maps are equal

2 Checking Equality of Two Maps with Different Sizes

We can also check if two maps with different sizes are equal in Dart by comparing their lengths first and then using the equality operator to compare their key-value pairs.

For example,

We start by declaring and initializing two maps named map1 and map2 with some key-value pairs. In this example, the maps have string keys and integer values, and they have different sizes.
We use an if statement to compare the lengths of map1 and map2. If their lengths are not equal, we print a message indicating that the maps are not equal.
If their lengths are equal, we use the equality operator (==) to check if the key-value pairs in both maps are equal.
We print the result to the console using the print function to indicate whether the maps are equal or not.

Dart Program

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

    // Check if the maps are equal
    if (map1.length != map2.length) {
        print('Maps are not equal');
    } else if (map1 == map2) {
        print('Maps are equal');
    } else {
        print('Maps are not equal');
    }
}

Output

Maps are not equal

3 Checking Equality of Two Maps Using a Helper Function

We can create a helper function to check if two maps are equal in Dart, which provides a reusable way to compare maps.

For example,

We start by declaring and initializing two maps named map1 and map2 with some key-value pairs. In this example, the maps have string keys and integer values.
We define a helper function named areMapsEqual that takes two maps as parameters and returns a boolean value indicating whether the maps are equal.
Inside the helper function, we compare the lengths of the maps. If their lengths are not equal, we return false.
If their lengths are equal, we use the equality operator (==) to check if the key-value pairs in both maps are equal and return the result.
We call the helper function with map1 and map2 as arguments and print the result to the console using the print function to indicate whether the maps are equal or not.

Dart Program

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

    // Helper function to check if two maps are equal
    bool areMapsEqual(Map<String, int> map1, Map<String, int> map2) {
        if (map1.length != map2.length) {
            return false;
        }
        return map1 == map2;
    }

    // Check if the maps are equal using the helper function
    if (areMapsEqual(map1, map2)) {
        print('Maps are equal');
    } else {
        print('Maps are not equal');
    }
}

Output

Maps are equal

Summary

In this tutorial, we learned How to Check if Two Maps are Equal in Dart language with well detailed examples.

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