Dart program to change single or multiple list item

Dart program to change single or multiple list item:

In this post, we will learn how to change one single element or multiple items of a list. Using the index, we can change any specific value of the list or we can change multiple items in the list in a range.

Updating one item using the index:

We can update any specific item in a list by using its index. We can access any item in a list by using the index and also, similarly, we can change the value at that index. For example:

void main() {
  List givenList = [1, 2, 3, 4, 5];
  givenList[0] = -1;

  print(givenList);
}

It will print:

[-1, 2, 3, 4, 5]

Here, we are changing the value of the first element or element at index 0 using the index. We are changing the value to -1.

Changing multiple items using replaceRange:

replaceRange is another method that can be used to replace all items in a range using a different iterable objects.

It is defined as below:

List.replaceRange(int start, int end, Iterable items)

Here,

start - It is the start index from where we want the replacement to start
end - It is the stop index for the replacement
items - An iterable objects those we are replacing

Let’s take a look at the below example:

void main() {
  List givenList = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
  List replace = [11, 12, 13, 14];

  givenList.replaceRange(0, 4, replace);

  print(givenList);
}

Here, we are replacing all elements of givenList in index range 0 to 4 with the second list replace.

It prints the below output:

[11, 12, 13, 14, 5, 6, 7, 8, 9, 10]

replaceRange if range is larger than the replacing iterable:

If the range in which we are replacing the items is less than the replacing objects, it will truncate the list.

For example:

void main() {
  List givenList = [1, 2, 3, 4, 5, 6, 7, 8, 9, 10];
  List replace = [11, 12, 13, 14];

  givenList.replaceRange(0, 9, replace);

  print(givenList);
}

It will print the below output:

[11, 12, 13, 14, 10]

replaceRange for invalid range:

It throws one RangeError for invalid range values. If I use the below range:

givenList.replaceRange(0, 29, replace);

It will throw an error like below:

CodeVsColor

Dart program to change single or multiple list item