Remove Item from Arraylist

How to remove specific object from ArrayList in Java?

ArrayList removes objects based on the equals(Object obj) method. So you should implement properly this method. Something like:

public boolean equals(Object obj) {
    if (obj == null) return false;
    if (obj == this) return true;
    if (!(obj instanceof ArrayTest)) return false;
    ArrayTest o = (ArrayTest) obj;
    return o.i == this.i;
}

Or

public boolean equals(Object obj) {
    if (obj instanceof ArrayTest) {
        ArrayTest o = (ArrayTest) obj;
        return o.i == this.i;
    }
    return false;
}

Remove Item from ArrayList

In this specific case, you should remove the elements in descending order. First index 5, then 3, then 1. This will remove the elements from the list without undesirable side effects.

for (int j = i.length-1; j >= 0; j--) {
    list.remove(i[j]);
}

Removing elements from ArrayList

This however leaves "empty spaces" in my list.

No, it doesn't. It removes entries from the list completely. Other elements are moved appropriately. What it does do with the way you've written is skip the check for the next entry... because that will have "shuffled down" to be element i, but you'll next look at element i + 1.

One simple way to avoid this is to work backwards instead:

for (int i = myList.size() - 1; i >= 0; i--) {
    if (myList.get(i).contains("foo")) {
        myList.remove(i);
    }
}

Or use an iterator as noted in other answers, of course. Both will work - the above code may be slightly more efficient if you're removing multiple entries, however, as there'll be less to shift by the time you get to the start. It's unlikely that that will be significant.

It's unfortunate that in order to use the iterator solution you have to use the iterator explicitly - you can't remove from a collection while using an enhanced for loop.

Android - Remove an item from arraylist by its ID

You can do like this

for(int i = 0 ; i < newsList.size() ; i++){
        if("yourId".equalsIgnoreCase(newsList.get(i).id)){
            newsList.remove(i);
        }
    }

Remove object by itself in ArrayList

You can use an Iterator, changing your attack method to accept it as a parameter:

Iterator<Bullet> iterator = bulletList.iterator();
while (iterator.hasNext()) {
    Bullet iBullet = iterator.next();
    iBullet.move();
    iBullet.attack(bulletList, iterator);
}

public void attack(ArrayList<Bullet> bulletList, Iterator<Bullet> iterator) {
    iterator.remove();
}

Or you can change your attack method to return a boolean indicating whether the bullet hit or not (instead of removing the bullet), and use the removeIf() method introduced in Java 8:

for (Bullet iBullet : bulletList) {
    iBullet.move();
}
bulletList.removeIf(b -> b.attack());

How to remove element from ArrayList?

You are facing ConcurrentModificationException because you are doing two operations on the same list at a time. i.e looping and removing same time.

Inorder to avoid this situation use Iterator,which guarantees you to remove the element from list safely .

A simple example looks like

Iterator<CartEntry> it = list.iterator();
    while (it.hasNext()) {
        if (it.next().getpId() == pId) {
            it.remove();
            break;
        }
    }

Java, how to remove an Integer item in an ArrayList

try this

list.removeAll(Arrays.asList(2));

it will remove all elements with value = 2

you can also use this

list.remove(Integer.valueOf(2));

but it will remove only first occurence of 2

list.remove(2) does not work because it matches List.remove(int i) which removes element with the specified index

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