How to Swap Keys and Values in a Map in Dart - Step by Step Examples

How to Swap Keys and Values in a Map in Dart ?

Answer

To swap keys and values in a map in Dart, you can iterate over the original map and insert each key-value pair into a new map with the value as the key and the key as the value. This method allows you to create a new map with swapped key-value pairs.

✐ Examples

1 Swapping Keys and Values in a Map of Integers

We can swap keys and values in a map of integers in Dart by iterating over the original map and inserting each key-value pair into a new map with the value as the key and the key as the value.

For example,

We start by declaring and initializing a map of integers named originalMap.
We declare an empty map named swappedMap to store the swapped key-value pairs.
We iterate over the original map using a for loop and insert each key-value pair into the new map with the value as the key and the key as the value.
We print the resulting map to the console to verify the swap.

Dart Program

void main() {
  // Declare and initialize a map of integers
  Map<int, int> originalMap = {
    1: 10,
    2: 20,
    3: 30,
    4: 40,
    5: 50
  };

  // Declare an empty map to store the swapped key-value pairs
  Map<int, int> swappedMap = {};

  // Iterate over the original map and insert each key-value pair into the new map with the value as the key and the key as the value
  originalMap.forEach((key, value) {
    swappedMap[value] = key;
  });

  // Print the resulting map
  print('Swapped map of integers:');
  swappedMap.forEach((key, value) {
    print('$key: $value');
  });
}

Output

Swapped map of integers:
10: 1
20: 2
30: 3
40: 4
50: 5

2 Swapping Keys and Values in a Map of Strings

We can swap keys and values in a map of strings in Dart by iterating over the original map and inserting each key-value pair into a new map with the value as the key and the key as the value.

For example,

We start by declaring and initializing a map of strings named originalMap.
We declare an empty map named swappedMap to store the swapped key-value pairs.
We iterate over the original map using a for loop and insert each key-value pair into the new map with the value as the key and the key as the value.
We print the resulting map to the console to verify the swap.

Dart Program

void main() {
  // Declare and initialize a map of strings
  Map<String, String> originalMap = {
    'one': 'uno',
    'two': 'dos',
    'three': 'tres',
    'four': 'cuatro',
    'five': 'cinco'
  };

  // Declare an empty map to store the swapped key-value pairs
  Map<String, String> swappedMap = {};

  // Iterate over the original map and insert each key-value pair into the new map with the value as the key and the key as the value
  originalMap.forEach((key, value) {
    swappedMap[value] = key;
  });

  // Print the resulting map
  print('Swapped map of strings:');
  swappedMap.forEach((key, value) {
    print('$key: $value');
  });
}

Output

Swapped map of strings:
uno: one
dos: two
tres: three
cuatro: four
cinco: five

3 Swapping Keys and Values in a Map of Mixed Types

We can swap keys and values in a map with mixed key and value types in Dart by iterating over the original map and inserting each key-value pair into a new map with the value as the key and the key as the value. This example demonstrates swapping keys of type int with values of type String.

For example,

We start by declaring and initializing a map with mixed types named originalMap.
We declare an empty map named swappedMap to store the swapped key-value pairs.
We iterate over the original map using a for loop and insert each key-value pair into the new map with the value as the key and the key as the value.
We print the resulting map to the console to verify the swap.

Dart Program

void main() {
  // Declare and initialize a map with mixed types
  Map<int, String> originalMap = {
    1: 'one',
    2: 'two',
    3: 'three',
    4: 'four',
    5: 'five'
  };

  // Declare an empty map to store the swapped key-value pairs
  Map<String, int> swappedMap = {};

  // Iterate over the original map and insert each key-value pair into the new map with the value as the key and the key as the value
  originalMap.forEach((key, value) {
    swappedMap[value] = key;
  });

  // Print the resulting map
  print('Swapped map of mixed types:');
  swappedMap.forEach((key, value) {
    print('$key: $value');
  });
}

Output

Swapped map of mixed types:
one: 1
two: 2
three: 3
four: 4
five: 5

Summary

In this tutorial, we learned How to Swap Keys and Values in a Map in Dart language with well detailed examples.

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