Remove values in ArrayList at indexes specified in int[]

The method takes an array of ints which are the indexes, and an ArrayList<String>. Items in the ArrayList with the index of the values in the index array are to be removed from the list.

When I run the following code, no items are removed. Can anyone explain what I’m doing wrong here?

  public static ArrayList<String> removeItems (ArrayList<String> list, int[]indexes){
         
         TreeSet<Integer> set = new TreeSet<>();
         
         for(Integer i : indexes) {
             set.add(i);
         }
         
        for(Integer i : set) {
            list.remove(i);
            i--;
        }
         
         return list;
     }

main method:

public static void main(String[] args) {
        
        ArrayList<String>list = new ArrayList<>();
        list.add("one");
        list.add("two");
        list.add("three");
        list.add("four");
        list.add("five");
        
    int[] arr = {2,3};

    ArrayList<String> newList = removeItems(list, arr);
    
    System.out.println(newList.toString());
    

}

>Solution :

There are 2 remove methods available for Lists, which seem somewhat identical, but do very different things:

• remove at an index: E remove(int index)
• remove an element from the list: boolean remove(Object o)

As you can see the 2nd method takes in an Object. Integer is an instance of Object. int on the other hand, is a primitive type. To be able to solve your problem you need to make sure you pass int to remove() instead of Integer.