Remove duplicate objects from a ArrayList in Android

Remove duplication of Custom Object

Example of Removing duplicate using Comparator

Lets suppose you have a class "Contact"

public class Contact implements Comparable<Contact> {


public String getName() {
    return this.Name;
}

public void setName(String name) {
    this.Name = name;
}

public String getNumber() {
    return this.Number;
}

public void setNumber(String number) {
    this.Number = number;
}


 ///// this method is very important you must have to implement it.
@Override
public String toString() {
    return "\n" +"Name=" + name + "   Number=" + Number;
}

Here is how you can remove duplicate entries using Set , just pass your list in the function and it will work for you. New list will be returned which will have no duplicated contacts.

 public ArrayList<Contact>  removeDuplicates(ArrayList<Contact> list){
    Set<Contact> set = new TreeSet(new Comparator<Contact>() {

        @Override
        public int compare(Contact o1, Contact o2) {
            if(o1.getNumber().equalsIgnoreCase(o2.getNumber())){
                return 0;
            }
            return 1;
        }
    });
    set.addAll(list);

    final ArrayList newList = new ArrayList(set);
    return newList;
}

It worked for me so please try and give me your feedback. Thanks

P.S: Credit goes to Nilanchala at this article

LinkedHashSet which keeps insertion-order can be used in your case.

HashSet: no order.

TreeSet: sorted set, but not keep insertion order.

EDIT: As Software Monkey commented, hashCode() and equals() should be overwritten in ContactObject to fit the hash-based Set.