Intersections of two lists in java

Question

I have used for and if loop to find intersections of list by comparing its inners JSON. I am looking for the solution using CollectionUtils or Java 8 or some other similar solution.

private List<IBXLocation> compareIbxLocationDetails(List<IBXLocation> serviceIbxsForLoggedInUser,
        List<IBXLocation> serviceIbxsForUser) {
    List<IBXLocation> finalList=new ArrayList();
    for (IBXLocation ibxForLoggedInUser : serviceIbxsForLoggedInUser) {
        String ibxSelected=ibxForLoggedInUser.getIbx();
        boolean ibxFound = false;
        ibxLoop:for (IBXLocation permittedIBXForUser : serviceIbxsForUser) {
            if (ibxSelected.equals(permittedIBXForUser.getIbx())) {
                IBXLocation newIbx = new IBXLocation(ibxSelected);
                List<Cage> newCageList=new ArrayList();
                if (!CollectionUtils.isEmpty(ibxForLoggedInUser.getCageDetails())) {
                    for (Cage selectedCage : ibxForLoggedInUser.getCageDetails()) {
                        String loggedInSelectedCageStr = selectedCage.getCage();
                        for (Cage permittedCage : permittedIBXForUser.getCageDetails()) {
                            if (loggedInSelectedCageStr.equals(permittedCage.getCage())) {
                                newCageList.add(permittedCage);
                            }

                        }
                        newIbx.setCageDetails(newCageList);
                    }
                    finalList.add(newIbx);
                }
                ibxFound = true;
                break ibxLoop;
            }

        }

    }

    return finalList;
}

The line newIbx.setCageDetails(newCageList); is probably a bug. It will keep overwriting the value. You should probably move it outside the loop to right before finalList.add(newIbx); — Misha
– Misha, Commented Jul 12, 2018 at 20:12
This code is working as expected, I am looking for solution using collectionUtils or Java 8 for same code. — user3352615
– user3352615, Commented Jul 12, 2018 at 21:09

Juan Carlos Rios Varas · Accepted Answer · 2018-07-12 21:10:46Z

1

You can use this

Set ibxForLoggedInUserToSet= new HashSet<IBXLocation>(ibxForLoggedInUser);

for(IBXLocation per: serviceIbxsForUser){
     if (ibxForLoggedInUserToSet.contains(per)){
          finalList.add(per);
     }
}

answered Jul 12, 2018 at 21:10

Juan Carlos Rios Varas

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ByeBye · Accepted Answer · 2018-07-12 22:22:25Z

0

In org.apache.commons.collections4.ListUtils there is a method public static <E> List<E> intersection(List<? extends E> list1, List<? extends E> list2)

answered Jul 12, 2018 at 22:22

ByeBye

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Mạnh Quyết Nguyễn · Accepted Answer · 2018-07-13 09:29:35Z

0

You can utilize Set to get intersections:

public <T> intersect(List<T> firstList, List<T> secondList) {
     Set<T> result = new HashSet<>();
     result.addAll(firstList);
     result.addAll(secondList);
     return result;
}

answered Jul 13, 2018 at 9:29

Mạnh Quyết Nguyễn

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