How to remove an array element from an Arraylist without using index in Java

Question

I want to remove the array int[]{1,2,3,4] from the list.

We can remove it from the list by the code list.remove(2) (2 is the index). But how we can remove this array by the function remove(Object obj) I thank you so much.

List list = new ArrayList();
    list.add("hello");
    list.add(10);
    list.add(new int[] { 1, 2, 3, 4 });

@ScaryWombat are you able to change the duplicate message or remove it since the OP commented on my answer they needed to remove an int array? — SamHoque, Dec 11 '18 at 08:36
I did not mark it as a dupe, @robby did, so I think it would be polite to ask him. — Scary Wombat, Dec 11 '18 at 08:39
If you have a reference to the same array, you can pass that to `remove(Object)`. Otherwise, you are better off using `remove(int)` and passing the appropriate index. — khelwood, Dec 11 '18 at 08:45

SamHoque · Accepted Answer · 2018-12-11T08:45:53.970

1

So, What's the issue here? Just cast the Int to an object.

list.remove((Object) 10);

Since you said you want to remove the int[] which wasn't specified in the question you can do so like this

Okay so I have put together a method.

public void removeIntArray(List list, int[] toRemove) {
    ListIterator listIterator = list.listIterator();
    while (listIterator.hasNext()) {
        Object object = listIterator.next();
        if (object instanceof int[]) {
            int[] ints = (int[]) object;
            if (Arrays.equals(ints, toRemove)) {
                listIterator.remove();
                break;
            }
        }
    }
}

Just call it as

removeIntArray(list, new int[]{1, 2, 3, 4});

edited Dec 11 '18 at 08:45

answered Dec 11 '18 at 08:31

SamHoque

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My aim is to remove the array {1,2,3,4} – loveCLoveC Dec 11 '18 at 08:34
Edited my answer, There you go :) – SamHoque Dec 11 '18 at 08:35
2

You'd have to pass the same array to `remove(Object)`, not a similar new array. Arrays do not support value-equality. – khelwood Dec 11 '18 at 08:40
I have no right to downvote you. that should be someone else. – loveCLoveC Dec 11 '18 at 08:41
@khelwood Ah, I never did this before so I thought it would be the same. I will come up with a solution. – SamHoque Dec 11 '18 at 08:42
@khelwood I have updated my answer, Can you verify if that will still give errors? – SamHoque Dec 11 '18 at 08:46
@ SamzSakerz I hope to hear from you soon. I thank you so much – loveCLoveC Dec 11 '18 at 08:47
@SamzSakerz No I can't, but you can compile and run it yourself and check. – khelwood Dec 11 '18 at 08:47
@khelwood. There's no error when I compile it. Just curious if it can break at certain times. – SamHoque Dec 11 '18 at 08:48
Still wondering why someone downvoted me, Was it you @khelwood? – SamHoque Dec 11 '18 at 08:55
@SamzSakerz No, not me. I wouldn't worry too much about one down vote. – khelwood Dec 11 '18 at 08:57
@khelwood not worried about down-vote, Just mildly annoyed because the down-voter said nothing as a feedback, So I don't know what to improve on my answer. – SamHoque Dec 11 '18 at 08:58

How to remove an array element from an Arraylist without using index in Java

1 Answers1