.clear()

Published Feb 15, 2024
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The .clear() method in Dart is used to remove all objects from a list, leaving an empty list in its place. This method is handy when we need to reset or clear the contents of a list, making it ready for new data. This method does not return any value.

Syntax

listName.clear();

Example

The .clear() method only works on a growable list. If the list is a fixed-length list, then it throws an Unsupported operation error and retains all objects in the list.

void main() {
// Creates a growable list with 3 elements with a default value of each element set to 1
final growableList = List<int>.filled(3, 1, growable: true);
print(growableList);
print(growableList.length);
// Clears all objects from the growable list
growableList.clear();
print(growableList);
print(growableList.length);
// 'false' is the default value for growable in 'List.filled' constructor
final fixedList = List<int>.filled(3, 3, growable: false);
print(fixedList);
// Throws an error for fixed list
fixedList.clear();
}

The output of the above code is:

[1, 1, 1]
3
[]
0
[3, 3, 3]
Uncaught Error: Unsupported operation: clear

Notes:

  • The .clear() method modifies the original list and does not create a new list.
  • After calling .clear(), the list will have a length of 0.
  • If the list is already empty, calling .clear() has no effect.
  • If the list is a fixed list, calling .clear() will throw an error.

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