Question

I have objects of a class Choice which are in a list.

Choice looks like this.

public class Choice extends MorphiaModel{   
    public String name;
    public Double price;
}

Some of them are empty, that is name is “” and price is null.

I want to remove these empty values.

I tried iterating over the list and removing them empty Choice objects, but I got a ConcurrentModificationException then I did this (after implementing equals and hashcode), but it doesn’t work, the empty values are still there.

Note: option.choices is a list of Choice objects

Choice emptyChoice = new Choice();
    emptyChoice.name = "";
    emptyChoice.price = null;

    option.choices.remove(emptyChoice);

Answer 1

The ConcurrentModificationException happened because you tried to remove the elements outside of the Iterator iterating over the list.

Something like this works:

Iterator<Choice> iterator = option.choices.iterator(); // or use option.choices.listIterator()

while (iterator.hasNext()) {
    if (emptyChoice.equals(iterator.next())) {
        iterator.remove();
    }
}