What is the time complexity of removing an element from an ArrayList in Java?

In Java, the operation of removing an element from an ArrayList has a worst-case time complexity of O(n). This is because ArrayList is implemented based on an array, and when removing an element, all subsequent elements are shifted one position to the left to fill the gap.

For example, if you remove an element at the beginning of the list, almost all other elements need to be shifted, which takes linear time. If you remove an element at the end, shifting is not required, and the operation is faster, but on average, it is considered O(n).

Therefore, for frequent removal operations, it is better to use data structures with more efficient removal, such as LinkedList.