I have two arraylists and I want to remove identical values between these lists, but only one occurrence of this. For example:
ArrayList<Integer> a = new ArrayList<>(Arrays.asList(1,2,3,4,5,6));
ArrayList<Integer> b = new ArrayList<>(Arrays.asList(1,2,3,1,2,3));
With these, function unique(a,b) would return:
[[4,5,6],[1,2,3]]
Assuming you want to return an ArrayList of ArrayLists, you can achieve this using this method:
private static ArrayList<ArrayList<Integer>> unique(ArrayList<Integer> a, ArrayList<Integer> b) {
ArrayList<ArrayList<Integer>> unique = new ArrayList<>();
unique.add(new ArrayList<>());
unique.add(new ArrayList<>());
for (Integer i: a) {
if (!b.contains(i) && !unique.get(0).contains(i)) {
unique.get(0).add(i);
}
}
for (Integer i: b) {
if (a.contains(i) && !unique.get(1).contains(i)) {
unique.get(1).add(i);
}
}
return unique;
}
If you only need to know the unique elements in a bunch of lists:
public static <T> ArrayList getUnique(List<T> ... lists){
Set<T> unique = new HashSet<T>();
for (List<T> eachList : lists){
unique.addAll(eachList);
}
return new ArrayList(unique);
}
And you can call it like this:
List<Integer> unique = getUnique(a,b);
@lmiguelvargasf - I took your function and modified it a little because it turns out your version only works if the numbers are all different already. Here is the new function:
private static ArrayList<ArrayList<Integer>> unique(ArrayList<Integer> a, ArrayList<Integer> b) {
ArrayList<ArrayList<Integer>> unique = new ArrayList<>();
unique.add(new ArrayList<>());
unique.add(new ArrayList<>());
for (Integer i: a) {
if (!b.contains(i)) {
unique.get(0).add(i);
}else{
b.remove(i);
}
}
for (Integer i: b) {
if (!a.contains(i)) {
unique.get(1).add(i);
}else{
b.remove(i);
}
}
return unique;
}