How to count the number of occurrences of an element in a List

Question

I have an ArrayList, a Collection class of Java, as follows:

ArrayList animals = new ArrayList();
animals.add(\"bat\         


        

Answer 1

I didn't want to make this case more difficult and made it with two iterators I have a HashMap with LastName -> FirstName. And my method should delete items with dulicate FirstName.

public static void removeTheFirstNameDuplicates(HashMap map)
{

    Iterator> iter = map.entrySet().iterator();
    Iterator> iter2 = map.entrySet().iterator();
    while(iter.hasNext())
    {
        Map.Entry pair = iter.next();
        String name = pair.getValue();
        int i = 0;

        while(iter2.hasNext())
        {

            Map.Entry nextPair = iter2.next();
            if (nextPair.getValue().equals(name))
                i++;
        }

        if (i > 1)
            iter.remove();

    }

}