ArrayList shrinking

Question

We know that ArrayList can expand or shrink dynamically. Can someone explain how the process of shrinking is handled internally?

Sudha Narayanan · Answer

Thanks Alan. I got that. You explained it beautifully.

Alan · Answer

The ArrayList class has a private field called _items which is of type object[] and which holds references to the objects added to the ArrayList. When you shrink the ArrayList by calling the TrimToSize() method or by setting the Capacity property explicitly a new object array of the reduced size is created and the elements of the existing _items array are copied over to it. The new array is then assigned to the _items field. As there will no longer be any references to the old array the memory will be reclaimed by the garbage collector in due course.