Question

I need to get the list of uncommon element while comparing two lists .
ex:-

List<String> readAllName = {"aaa","bbb","ccc","ddd"};
List<String> selectedName = {"bbb","ccc"};

here i want uncommon elements from readAllName list (“aaa”,”ccc”,”ddd”) in another list.
Without Using remove()and removeAll().

Answer 1

Assuming the expected output is aaa, ccc, eee, fff, xxx (all the not-common items), you can use List#removeAll, but you need to use it twice to get both the items in name but not in name2 AND the items in name2 and not in name:

List<String> list = new ArrayList<> (name);
list.removeAll(name2); //list contains items only in name

List<String> list2 = new ArrayList<> (name2);
list2.removeAll(name); //list2 contains items only in name2

list2.addAll(list); //list2 now contains all the not-common items

---

As per your edit, you can’t use remove or removeAll – in that case you can simply run two loops:

List<String> uncommon = new ArrayList<> ();
for (String s : name) {
    if (!name2.contains(s)) uncommon.add(s);
}
for (String s : name2) {
    if (!name.contains(s)) uncommon.add(s);
}