Java ArrayList independent copy

Question

I used the method below to make a copy of a list, as you can see the output, they are independent. Did I get something wrong? or are they really independent? because I did some research on the internet, and it told me this method should pass-by-reference (which list 'a' and 'copy' should be dependent).

public static void main(String[] args) {
    ArrayList<String> a = new ArrayList<>(Arrays.asList("X", "X"));
    ArrayList<String> copy = new ArrayList<>(a);
    copy.set(0, "B");
    copy.remove(copy.size()-1);
    System.out.println(a);
    System.out.println(copy);
}

Output:

[X, X]
[B]

Answer 1

Yes, this method should pass-by-reference (which list 'a' and 'copy' should be dependent). But these two operations don't prove this.

copy.set(0, "B");
copy.remove(copy.size()-1);

See if the following code helps you understand:

    public static void main(String[] args) {
        Process process = new Process(1);
        Process process2 = new Process(2);
        ArrayList<Process> a = new ArrayList<>(Arrays.asList(process, process2));
        ArrayList<Process> copy = new ArrayList<>(a);
        copy.get(0).id = 10;

        // This proves that both ArrayLists maintain the same Process object at this point
        // output:
        // [Id:10, Id:2]
        // [Id:10, Id:2]
        System.out.println(a);
        System.out.println(copy);


        // copy.remove(copy.size() - 1) or copy.set(0, process3) doesn't affect another ArrayList
        Process process3 = new Process(3);
        process3.id = 100;
        copy.set(0, process3);
        copy.remove(copy.size() - 1);
        // output:
        // [Id:10, Id:2]
        // [Id:100]
        System.out.println(a);
        System.out.println(copy);

    }

    static class Process {
        public int id;

        public Process(int id) {
            this.id = id;
        }

        @Override
        public String toString() {
            return "Id:" + id;
        }
    }