How to Check if a Value Exists in a Map in Dart

How to Check if a Value Exists in a Map in Dart ?

Answer

To check if a value exists in a map in Dart, you can use the containsValue method. This method returns a boolean value indicating whether the map contains the specified value.

✐ Examples

1 Checking if a Value Exists Using containsValue Method

We can check if a value exists in a map in Dart using the containsValue method, which returns true if the map contains the specified value and false otherwise.

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 containsValue method to check for a specific value in the map. The containsValue method returns a boolean value indicating whether the map contains the specified value.
We print the result 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
    };

    // Check if a value exists using containsValue method
    bool valueExists = myMap.containsValue(2);

    // Print the result
    print('Does value 2 exist? $valueExists');
}

Output

Does value 2 exist? true

2 Checking if a Value Does Not Exist Using containsValue Method

We can check if a value does not exist in a map in Dart using the containsValue method, which returns false if the map does not contain the specified value.

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 containsValue method to check for a specific value in the map. The containsValue method returns a boolean value indicating whether the map contains the specified value.
We print the result 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
    };

    // Check if a value does not exist using containsValue method
    bool valueExists = myMap.containsValue(4);

    // Print the result
    print('Does value 4 exist? $valueExists');
}

Output

Does value 4 exist? false

3 Checking Multiple Values Using containsValue Method

We can check if multiple values exist in a map in Dart using the containsValue method, which returns true if the map contains the specified value and false otherwise.

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 containsValue method to check for multiple values in the map. The containsValue method returns a boolean value indicating whether the map contains the specified value.
We print the results 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
    };

    // Check if multiple values exist using containsValue method
    bool valueExistsOne = myMap.containsValue(1);
    bool valueExistsFour = myMap.containsValue(4);

    // Print the results
    print('Does value 1 exist? $valueExistsOne');
    print('Does value 4 exist? $valueExistsFour');
}

Output

Does value 1 exist? true
Does value 4 exist? false

Summary

In this tutorial, we learned How to Check if a Value Exists in a Map in Dart language with well detailed examples.

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How to Check if a Value Exists in a Map in Dart