Why am I getting IndexOutOfBoundsException?

Question

I am trying to make an inventory system and am using the following code. I tried adding numberOfItems-- because I thought that was the problem but that doesn't seem to be it.

public static void delete(String title) {
    for(int i = 0; i < numberOfItems; i++) {
        if(newItem.get(i).getTitle().equalsIgnoreCase(title)){
            newItem.remove(i);
        }
    }
}

case 5:
    String name = "";
    System.out.println("What is the name of the item?");
    name = userInput.nextLine();
    delete(name);
    numberOfItems--;
    break;

This may help https://stackoverflow.com/questions/5554734/what-causes-a-java-lang-arrayindexoutofboundsexception-and-how-do-i-prevent-it — Angela Amarapala, Dec 13 '19 at 17:15
It's usually a bad idea to modify a collection while iterating through it. Or rather, it's a common source of bugs — byxor, Dec 13 '19 at 17:15
You would also need to `i--`, but I'd suggest using an `Iterator` and their `.remove()` method instead. — Aaron, Dec 13 '19 at 17:16
What does `newItem` consist of? Is it a List or an Array? Generally you should use an iterator for lists if you plan to modify them while looping/iterating over it. — Dennis B., Dec 13 '19 at 17:17
Add a break to the if condition once you remove the item. Should be fine then (Assuming you always input a correct "name" that exists on the list. Since you decrement numerOfItems without any validation) — saiftyfirst, Dec 13 '19 at 17:27

score 1 · Answer 1 · answered Dec 13 '19 at 17:27

With newItem.remove(i) you're modifying that list (I guess it is a list, that's not clear from your example) while iterating over it. That's usually not a good idea.

There are different ways you could do this correctly. For example:

private static void delete(String title) {
    Iterator<ArrayElement> iterator = newItem.iterator();
    while (iterator.hasNext()) {
        if (iterator.next().getTitle().equalsIgnoreCase(title)) {
            iterator.remove();
        }
    }
}

Why am I getting IndexOutOfBoundsException?

1 Answers1