List.add()
Adds an element to the end of a list or at a given position.
Available since: Java 1.2
Syntax
boolean add(E e)
void add(int index, E element)Parameters
| Parameter | Type | Description |
|---|---|---|
| index | int | Optional insert position; elements from this position shift to the right. |
| e | E | The element to add. |
Return value
booleanThe version without an index returns `true`; the version with an index returns nothing.
Examples
Adding to the end:
void main() {
List<String> fruits = new ArrayList<>();
fruits.add("apple");
fruits.add("pear");
IO.println(fruits);
}Output:
[apple, pear]Inserting at an index:
void main() {
List<String> fruits = new ArrayList<>(List.of("apple", "pear"));
fruits.add(0, "kiwi");
fruits.add(2, "plum");
IO.println(fruits);
}Output:
[kiwi, apple, plum, pear]Notes
The index may be from 0 to size() inclusive: add(size(), x) is the same as add(x). A larger index throws IndexOutOfBoundsException. Unmodifiable lists (List.of()) throw UnsupportedOperationException.
See also
- List.addAll() — Adds all elements of another collection to a list.
- List.set() — Replaces the list element at an index.
- List.remove() — Removes a list element by index or by value.
- ArrayList — A resizable list backed by an array — the most common `List` implementation.
Related recipes
In the tutorial
- Lists: List and ArrayList — Lists in Java: ArrayList, adding, reading and removing elements, unmodifiable List.of lists and lists of numbers.