How is an element removed from an ArrayList collection in Java?

Removing an element from an ArrayList in Java is done as follows:

1. Find the index of the element to be removed (if removing by object, first find the index).
2. All elements after the removed element are shifted one position to the left to fill the gap.
3. The size of the list decreases by 1.

Because of the shifting of elements, the removal operation in ArrayList has a worst-case time complexity of O(n).

Example of removal by index:

ArrayList<String> list = new ArrayList<>();
list.add("A");
list.add("B");
list.add("C");

list.remove(1); // removes the element "B"
// Now list contains ["A", "C"]