What is used to iterate through a collection and can remove elements from the collection during the iteration?

What is used to iterate through a collection and can remove elements from the collection during the iteration?

An element can be removed from a Collection using the Iterator method remove(). This method removes the current element in the Collection. If the remove() method is not preceded by the next() method, then the exception IllegalStateException is thrown.

Which method is used to delete all element from collection?

clear() method removes all the elements from invoking collection.

Can we remove an element from an ArrayList while iterating with iterator?

ArrayList provides the remove() methods, like remove (int index) and remove (Object element), you cannot use them to remove items while iterating over ArrayList in Java because they will throw ConcurrentModificationException if called during iteration.

How does remove work in ArrayList?

The remove() method is used to remove an element at a specified index from ArrayList. Shifts any subsequent elements to the left (subtracts one from their indices). The index of the element to be removed.

Can we delete the elements in ArrayList If so then will the ArrayList shrink?

Does the capacity of an ArrayList decrease when we remove elements? No. This is an implementation detail, but AFAIK no (standard) implementation of the ArrayList class has ever reduced the capacity automatically of a list automatically when elements are deleted.

How to remove elements from a list while iterating over it?

Use a standard for-loop running backwards on your collection and RemoveAt (i) to remove elements. Reverse iteration should be the first thing to come to mind when you want to remove elements from a Collection while iterating over it.

What’s the point of iterating over a collection?

There’s really no point in iterating over the collection to remove a single item. Why don’t you just simply decrement the iterator variable? Here is a dirty trick and I wonder what the critique of it will be?

Is there a way to remove an item from a collection?

You could try ChrisF’s reverse iteration method to remove your item. And be done with it. There’s really no point in iterating over the collection to remove a single item. Why don’t you just simply decrement the iterator variable?

When to remove elements from a generic list?

The compiler makes a copy of “list”, so that you can safely do the remove on the array. While this pattern is not super efficient, it has a natural feel and is flexible enough for almost any situation. Such as when you want to save each “item” to a DB and remove it from the list only when the DB save succeeds.