I am trying to compare weather an item is contained within the arrayList and if it is then remove it. Im not sure weather I have to implement my own equals method or not, this is my code but it isn't working to remove the correct item.
public boolean removeItem(Item item) {
for(int i = 0; i < items.size(); i++) {
if (items.get(i).equals(item)) {
items.remove(item);
return true;
}
}
return false;
}
ArrayList#remove(Object) will do exactly that! But this works only if you have overridden the equals method of Item.
If You want to remove all elements, will need a loop:
public int remove(Item item) {
int i = 0;
while(list.remove(item)) {
i++;
}
return i;
}
this will return the amount of items that have been removed
Removes the first occurrence of the specified element from this list, if it is present. If the list does not contain the element, it is unchanged. More formally, removes the element with the lowest index i such that (o==null ? get(i)==null : o.equals(get(i))) (if such an element exists). Returns true if this list contained the specified element (or equivalently, if this list changed as a result of the call).
O(k*n) where k is list.size() and n is the number item currencies. This could be done i O(k) using list.iterator() and iterator.remove().You can safely remove items from a Collection using Iterator
public boolean removeItem(Item item) {
Iterator<Item> it = items.iterator();
while (it.hasNext()) {
Item i = it.next();
if(i.equals(item)) {
it.remove();
// remove next line if you want to remove all occurrences `item`
return true;
}
}
return false;
}
You could also just call
items.remove(item);
I think you want contains not equals`. You don't even need to loop it. That's the magic of the method.
public boolean removeItem(Item item) {
if (items.contains(item)){
items.remove(item);
}
return false; // I have no idea why you want to return false.
// I'll just leave it there
}
romove is no function of arraylist
contains() and again for remove(). You might as well just call remove() and let it fail if the item isn't in the list.Yes you have to override equals in your class.Compare every single attribute and when one of them dont equals the other, then return false. If you use eclipse for example, you can let it create the equals method for your class.
containsandremovemethods ofArrayList.Itemclasscontainsnot equals`. You don't even need to loop it.