When to use LinkedList over ArrayList in Java?

In Java, both ArrayList and LinkedList are implementations of the List interface that allow you to store a collection of objects in a specific order. However, they are implemented differently and have different performance characteristics.

ArrayList is implemented using an array, which means that it has fast access times for elements at a specific index. However, it is slower to insert or remove elements at the beginning or middle of the list, since it requires shifting the subsequent elements to make room for the new element or close the gap left by the removed element.

LinkedList is implemented using a linked list data structure, which means that it has fast insert and remove operations at the beginning or middle of the list, since it only requires updating the pointers of the surrounding elements. However, it is slower to access elements at a specific index, since it requires iterating through the list from the beginning or end to find the element.

In general, you should use ArrayList when you need fast access to elements at a specific index and you are not frequently inserting or removing elements. You should use LinkedList when you need fast insert and remove operations and you are not frequently accessing elements by index.

Note that ArrayList has a slightly higher overhead than LinkedList, since it stores the elements in an array that needs to be resized and copied when the list grows or shrinks. However, this overhead is usually not significant unless you are working with very large lists.