how to switch elements in an ArrayList

Question

The following ArrayList populates a ArrayAdapter.

List<String> hold_people = new ArrayList<String>();

hold_people.add("Frank");
hold_people.add("Bob");
hold_people.add("Tom");
hold_people.add("Alice");
hold_people.add("Glen");

Frank is in the first spot. but the user wants to see Alice first. How do move Alice to the first spot ?

I can not sort it alphabetically because i must maintain a certain order... based on user request.

Answer 1

You can use Collections.swap.

Collections.swap(hold_people, 0, hold_people.indexOf("Alice"));

This will swap the element that is first in the list with "Alice".

Be aware that hold_people.indexOf("Alice") can return -1 if you don't have the String "Alice" in your list, so you may check that the list contains it.

int index = hold_people.indexOf("Alice");
if(index != -1)
    Collections.swap(hold_people, 0, index);