Example of when IntArrayList would be more efficient and when IntVector would be more efficient. IntArrayList It is more efficient if the number of elements added grows slowly over time, because it doesn't expand as large. For example, in applications where the initial list size is small, like a shopping cart in an online store. IntVector It is more efficient when the list is expected to grow significantly. For example, with large amounts of data that will continually grow, like storing large temporary datasets.