What is the List insert() method in Dart?

List insert() method

The insert() method in Dart is used to insert an element at a specific index in the list. This increases the list’s length by one and moves all elements after the index towards the end of the list.

Syntax

list_name.insert(int index, E element);

Parameters

  • index: Specifies the index where the element will be inserted in the list.
  • element: Represents the value to be inserted.

Note: The index value must be valid. The valid index ranges from 0…N, where N is the number of elements in the list.

Return value

The insert() method does not return anything.

Example

The following code shows how to use the insert() method in Dart:

void main(){
  // Create List fruits
  List<String> fruits = ['Mango', 'Pawpaw', 'Avocado', 'Pineapple', 'Lemon'];
  // Display result
  print("Original list $fruits");
  // Insert new item in the list 
  // using insert()
  fruits.insert(2, "Apple");
  // Display result
  print('The new list: ${fruits}');
}

Note: The length of the list will increase by one each time the method insert() is used.

Explanation

  • Line 3: We create a list named fruits.
  • Line 5: We print the items in the list.
  • Line 8: We use the method insert() to add a new item at index 2.
  • Line 10: Finally, the result is printed.

As indexing starts at 0, the above code will insert Apple as the third element, shifting Avocado, Pineapple, and Lemon to the right by one position.

Note: Passing an invalid index value will throw a RangeError exception.

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