Arrays.asList()

Examples

A list from values; elements can change, the size cannot:

void main() {
    List<String> list = Arrays.asList("a", "b", "c");
    list.set(0, "z");
    IO.println(list);
    try {
        list.add("d");
    } catch (UnsupportedOperationException e) {
        IO.println("cannot add");
    }
}

Output:

[z, b, c]
cannot add

A regular mutable list from an array — wrap it in an ArrayList:

void main() {
    String[] array = {"Anna", "Oleg"};
    List<String> names = new ArrayList<>(Arrays.asList(array));
    names.add("Maria");
    IO.println(names);
}

Output:

[Anna, Oleg, Maria]

Notes

The list and the array are linked: set() changes the array, and changes to the array show up in the list. For an immutable list List.of(...) is handier. With a primitive array the method behaves unexpectedly: Arrays.asList(new int[] {1, 2}) returns a list of one element — the array itself; for int[] use Arrays.stream(a).boxed().toList().