Add Elements to ArrayList that is inside LinkedHashMap [Android]

Question

I have a list of Users, each with a list of their Groups. Something like this:

John -->[GroupA]

Peter --> [GroupB, GroupC]

Bob --> [GroupC]

Tom --> [GroupA,GroupB]

Jack --> []

Then I have my own list of groups:

Me -->[GroupA, GroupB, GroupC].

So what I want is to put the users in a "bucket" that matches their groups with mine. If the user has no groups, their will be added to a Generic group, in the list. So the result has to be something like:

Contacts:

{ GroupA:[John, Tom], GroupB:[Peter, Tom], GroupC:[Peter, Bob], Generic:[Jack]}

So I test something like this, but, It generates duplicated values on the LinkedHashMap, and I don't know how to solve it.

    private void createVoidCollection() {
            groupsCollections = new LinkedHashMap<String, List<RosterEntry>>();
            ArrayList<RosterEntry> contacts = new ArrayList<RosterEntry>();
            for (String group : groupList) {
                groupsCollections.put(group, contacts);

            }
        }

    private void createContactListCollection() {
            createVoidCollection();

            boolean bAdded = false;

            //Returns a Collection of USers/contacts
            Collection<RosterEntry> contacts = mRoster.getEntries();

            for (RosterEntry buddy : contacts) {
                //We get the groups that pertains every contact/user
                Collection<RosterGroup> buddyGroups = buddy.getGroups();
                List<RosterEntry> contactsAux = new ArrayList<RosterEntry>();

                for (RosterGroup group : buddyGroups) {     
                    //For all the groups of the user, we check if is in some of my groups. If not they will be added to a generic group.        
                    if (groupList.contains(group.getName())) {
                        contactsAux = groupsCollections.get(group.getName());
                        contactsAux.add(buddy);
                        groupsCollections.put(group.getName(), contactsAux);
                        bAdded = true;
                    }
                }
                if (!bAdded) {

                    //The generic group is checked if exist or not, to be created if neeeded.
                    if (groupsCollections.containsKey(mBuddGroup)) {
                        contactsAux = groupsCollections.get(mBuddGroup);
                        contactsAux.add(buddy);
                        groupsCollections.put(mBuddGroup, contactsAux);
                    } else {
                        contactsAux.add(buddy);
                        groupsCollections.put(mBuddGroup, contactsAux);
                        groupList.add(mBuddGroup);
                    }
                }
                bAdded = false;

            }

        }

Question:

How can I solve it? Is there any way to do it better?

My groups list:

DEV-andorraCASS2007
D40-E30-Kosmos

The Contacts and Group list of each one is:

User:
    pruebaopenfire
        Groups: 
            D40-E30-Kosmos
User:
    Diana P
        Groups: 
            DEV-andorraCASS2007
            D40-E30-Kosmos
User:
    Fabio C
        Groups: 
            D40-E30-Kosmos
User:
    Alejandro 
        Groups: 
            DEV-andorraCASS2007
User:
    Jordi C
        Groups: 
            DEV-andorraCASS2007
            D40-E30-Kosmos
User:
    Mikel S
        Groups: 
            D40-E30-Kosmos
User:
    AAAAA
        Groups: 
User:
    Rubén R
        Groups: 
            DEV-andorraCASS2007
            D40-E30-Kosmos
User:
    Diego M
        Groups: 
            D40-E30-Kosmos
User:
    jfkgl
        Groups: 
User:
    Luis T
        Groups: 
            DEV-andorraCASS2007
            D40-E30-Kosmos
User:
    Melissa Y
        Groups: 
            D40-E30-Kosmos
User:
    Prova Prova
        Groups: 
            D40-E30-Kosmos

The result is:

02-16 13:22:13.436: D/TESTINGGROUPS(6056): 
{
    DEV-andorraCASS2007=[Diana P: [email protected] [DEV-andorraCASS2007, D40-E30-Kosmos], Diana P: [email protected] [DEV-andorraCASS2007, D40-E30-Kosmos], Alejandro Q: [email protected] [DEV-andorraCASS2007], Mikel S: [email protected] [D40-E30-Kosmos], Rubén R: [email protected] [DEV-andorraCASS2007, D40-E30-Kosmos], Rubén R: [email protected] [DEV-andorraCASS2007, D40-E30-Kosmos], Diego M: [email protected] [D40-E30-Kosmos], Jordi C: [email protected] [DEV-andorraCASS2007, D40-E30-Kosmos], Jordi C: [email protected] [DEV-andorraCASS2007, D40-E30-Kosmos], Luis T: [email protected] [DEV-andorraCASS2007, D40-E30-Kosmos], Luis T: [email protected] [DEV-andorraCASS2007, D40-E30-Kosmos], Prova Prova: [email protected] [D40-E30-Kosmos], pruebaopenfire: [email protected] [D40-E30-Kosmos], Melissa Y: [email protected] [D40-E30-Kosmos], Fabio C: [email protected] [D40-E30-Kosmos]], 

    D40-E30-Kosmos=[Diana P: [email protected] [DEV-andorraCASS2007, D40-E30-Kosmos], Diana P: [email protected] [DEV-andorraCASS2007, D40-E30-Kosmos], Alejandro Quintana: [email protected] [DEV-andorraCASS2007], Mikel Sobradillo Ecenarro: [email protected] [D40-E30-Kosmos], Rubén R: [email protected] [DEV-andorraCASS2007, D40-E30-Kosmos], Rubén R: [email protected] [DEV-andorraCASS2007, D40-E30-Kosmos], Diego M: [email protected] [D40-E30-Kosmos], Jordi C: [email protected] [DEV-andorraCASS2007, D40-E30-Kosmos], Jordi C: [email protected] [DEV-andorraCASS2007, D40-E30-Kosmos], Luis T: [email protected] [DEV-andorraCASS2007, D40-E30-Kosmos], Luis T: [email protected] [DEV-andorraCASS2007, D40-E30-Kosmos], Prova Prova: [email protected] [D40-E30-Kosmos], pruebaopenfire: [email protected] [D40-E30-Kosmos], Melissa Y: [email protected] [D40-E30-Kosmos], Fabio C: [email protected] [D40-E30-Kosmos]], 

    Otros Contactos=[jfkgl: jhgfk, AAAAA: [email protected]]
}

please show result what getting in LinkedHashMap with current logic — ρяσѕρєя K
– ρяσѕρєя K, Commented Feb 16, 2015 at 12:17

Matt · Accepted Answer · 2015-02-16 12:26:15Z

2

Heres a solution using sets, which will automatically avoid duplicates:

    Map<String, List<String>> userToGroup = new HashMap<String, List<String>>();
    userToGroup.put("John", Arrays.asList("GroupA"));
    userToGroup.put("Peter", Arrays.asList("GroupB", "GroupC"));
    userToGroup.put("Bob", Arrays.asList("GroupC"));
    userToGroup.put("Tom", Arrays.asList("GroupA", "GroupB"));
    userToGroup.put("Jack", Collections.<String> emptyList());

    Set<String> myGroups = new HashSet<String>(Arrays.asList("GroupA", "GroupB", "GroupC"));

    Map<String, Set<String>> groupToUsers = new HashMap<String, Set<String>>();
    groupToUsers.put("Generic", new HashSet<String>());
    for (String user : userToGroup.keySet()) {
        List<String> groups = userToGroup.get(user);
        if (groups.isEmpty()) {
            groupToUsers.get("Generic").add(user);
            continue;
        }

        for (String group : groups) {
            if (!myGroups.contains(group)) {
                continue;
            }

            Set<String> userInGroup = groupToUsers.get(group);
            if (userInGroup == null) {
                userInGroup = new HashSet<String>();
                groupToUsers.put(group, userInGroup);
            }

            userInGroup.add(user);
        }
    }

    System.out.println(groupToUsers);

Output:

{GroupC=[Bob, Peter], GroupB=[Tom, Peter], GroupA=[Tom, John], Generic=[Jack]}

answered Feb 16, 2015 at 12:26

Matt

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1 Comment

Shudy Over a year ago

Thanks in advanced!, I'm gonna try and tell something ^^

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