[java] Add multiple items to already initialized arraylist in java

I'm googling it and can't seem to find the syntax. My arraylist might be populated differently based on a user setting, so I've initialized it

ArrayList<Integer> arList = new ArrayList<Integer>();

And now I'd like to add hundred of integers without doing it one by one with arList.add(55);

If you needed to add a lot of integers it'd proabbly be easiest to use a for loop. For example, adding 28 days to a daysInFebruary array.

ArrayList<Integer> daysInFebruary = new ArrayList<>();

for(int i = 1; i <= 28; i++) {
    daysInFebruary.add(i);
}

I believe the answer above is incorrect, the proper way to initialize with multiple values would be this...

int[] otherList ={1,2,3,4,5};

so the full answer with the proper initialization would look like this

int[] otherList ={1,2,3,4,5};
arList.addAll(Arrays.asList(otherList));

Collections.addAll is a varargs method which allows us to add any number of items to a collection in a single statement:

List<Integer> list = new ArrayList<>();
Collections.addAll(list, 1, 2, 3, 4, 5);

It can also be used to add array elements to a collection:

Integer[] arr = ...;
Collections.addAll(list, arr);

If you are looking to avoid multiple code lines to save space, maybe this syntax could be useful:

        java.util.ArrayList lisFieldNames = new ArrayList() {
            {
                add("value1"); 
                add("value2");
            }
        };

Removing new lines, you can show it compressed as:

        java.util.ArrayList lisFieldNames = new ArrayList() {
            {
                add("value1"); add("value2"); (...);
            }
        };

What is the "source" of those integer? If it is something that you need to hard code in your source code, you may do

arList.addAll(Arrays.asList(1,1,2,3,5,8,13,21));