public class Strings{
    public static void swapMaxes(List<String> list1, List<String> list2){
    if(list1 == null || list2 == null || list1.size() == 0 || list2.size()==0){
    throw new IllegalArgumentException("cannot swap maxes of empty lists, null lists, or lists with all null elements");

    int longString1 = 0;
    int position1;
    for(int i = 0; i < list1.size(); i ++) {
        if(list1.get(i).length() > longString1) {
            longString1 = list1.get(i).length();
            position1 = i;
        }
    }
    int longString2 = 0;
    int position2;
    for(int j = 0; j < list2.size(); j ++) {
        if(list2.get(j).length() > longString2) {
            longString1 = list1.get(j).length();
            position1 = j;
        }
    }
    }
        }
    }