Simple way to compare 2 ArrayLists

Question

I have 2 arraylists of string object.

List sourceList = new ArrayList();
List destinationList = new ArrayList

        

Answer 1

private int compareLists(List<String> list1, List<String> list2){
    Collections.sort(list1);
    Collections.sort(list2);

    int maxIteration = 0;
    if(list1.size() == list2.size() || list1.size() < list2.size()){
        maxIteration = list1.size();
    } else {
        maxIteration = list2.size();
    }

    for (int index = 0; index < maxIteration; index++) {
        int result = list1.get(index).compareTo(list2.get(index));
        if (result == 0) {
            continue;
        } else {
            return result;
        }
    }
    return list1.size() - list2.size();
}

Answer 2

As far as I understand it correctly, I think it's easiest to work with 4 lists: - Your sourceList - Your destinationList - A removedItemsList - A newlyAddedItemsList

Answer 3

The answer is given in @dku-rajkumar post.

ArrayList commonList = CollectionUtils.retainAll(list1,list2);

Answer 4

The simplest way is to iterate through source and destination lists one by one like this:

List<String> newAddedElementsList = new ArrayList<String>();
List<String> removedElementsList = new ArrayList<String>();
for(String ele : sourceList){
    if(destinationList.contains(ele)){
        continue;
    }else{
        removedElementsList.add(ele);
    }
}
for(String ele : destinationList){
    if(sourceList.contains(ele)){
        continue;
    }else{
        newAddedElementsList.add(ele);
    }
}

Though it might not be very efficient if your source and destination lists have many elements but surely its simpler.