Question

Suppose an ArrayList list contains {"red", "red", "green"}. What is list after the following code?

String element = "red";
for (int i = () - 1; i >= 0; i--)
if ( (i).equals(element))
list.remove(element);


A. {"red", "red", "green"}
B. {"red", "green"}
C. {"green"}
D. {}

Answer 1

The question is about an ArrayList in Java and how it is modified by a loop. After correcting the error in the loop, assuming it should compare using list.get(i), and understanding that the list is traversed backwards, all 'red' elements are removed, leaving {'green'}.

Step-by-step explanation:

The question pertains to a situation involving an ArrayList in Java and manipulations using a for loop. Initially, the list contains {"red", "red", "green"}. The provided code intends to remove elements from the list that match the string "red". However, there seems to be a typo or a missing part where (i) is mentioned. It appears that it should be list.get(i) instead, which would retrieve the element at index i from the list.

Assuming the code's intention is to remove elements that are equal to the string stored in element, and correcting it to list.get(i).equals(element), the loop starts from the end of the list and moves towards the beginning. There is also a potential issue with the removal of elements; the code currently attempts to remove by value using list.remove(element). If element appears multiple times, it will always remove the first occurrence and could lead to unintended behavior when indices change due to removals.

However, because the code is traversing backwards, it should still function correctly, removing all "red" elements. After executing the corrected version of this code, the ArrayList would be: {"green"}, since both occurrences of "red" would be removed.