Dart Map removeWhere()
Syntax & Examples
Syntax of Map.removeWhere()
The syntax of Map.removeWhere() method is:
void removeWhere(bool test(K key, V value))
This removeWhere() method of Map removes all entries of this map that satisfy the given test
.
Parameters
Parameter | Optional/Required | Description |
---|---|---|
test | required | the function that determines if an entry should be removed |
Return Type
Map.removeWhere() returns value of type void
.
✐ Examples
1 Remove entries with even values
In this example,
- We create a map
map
with some key-value pairs. - We use the
removeWhere()
method with a function that removes entries with even values. - The entries with even values ('two': 2) are removed from the map.
- The updated map
map
is printed, showing the remaining entries.
Dart Program
void main() {
Map<String, int> map = {'one': 1, 'two': 2, 'three': 3};
map.removeWhere((key, value) => value % 2 == 0);
print(map); // Output: {one: 1, three: 3}
}
Output
{one: 1, three: 3}
2 Remove entries with values of length 3
In this example,
- We create a map
map
with some key-value pairs. - We use the
removeWhere()
method with a function that removes entries with values of length 3. - The entry with value 'One' and 'Two' are removed from the map, because of their length being 3.
- The updated map
map
is printed, showing the remaining entries.
Dart Program
void main() {
Map<int, String> map = {1: 'One', 2: 'Two', 3: 'Three'};
map.removeWhere((key, value) => value.length == 3);
print(map); // Output: {1: One}
}
Output
{3: Three}
3 Remove entries with keys starting with 't'
In this example,
- We create a map
map
with some key-value pairs. - We use the
removeWhere()
method with a function that removes entries with keys starting with 't'. - The entries with keys 'taste' and 't' are removed from the map.
- The updated map
map
is printed, showing the remaining entries.
Dart Program
void main() {
Map<String, String> map = {'fruit': 'apple', 'color': 'red', 'taste': 'sweet'};
map.removeWhere((key, value) => key.startsWith('t'));
print(map); // Output: {fruit: apple, color: red}
}
Output
{fruit: apple, color: red}
Summary
In this Dart tutorial, we learned about removeWhere() method of Map: the syntax and few working examples with output and detailed explanation for each example.