description

# retainWhere method

void retainWhere(

1. bool test(
   1. E element
   )

)
override

Removes all objects from this list that fail to satisfy `test`.

An object `o` satisfies `test` if `test(o)` is true.

    final numbers = <String>['one', 'two', 'three', 'four'];
    numbers.retainWhere((item) => item.length == 3);
    print(numbers); // [one, two]

The list must be growable.

## Implementation

    void retainWhere(bool test(E element)) {
      _filter(test, true);
    }