In my program I have an array list containing product objects in it. I want to remove duplicated product objects from it. Is there any efficient way other than looping over each element and compare them.
-
1Look at this: stackoverflow.com/questions/5741038/…Unii– Unii2013-12-05 09:21:22 +00:00Commented Dec 5, 2013 at 9:21
Add a comment
|
7 Answers
just add all element into set. it wont allow duplicate values
List<Product> list=new ArrayList<>();
Set<Product> set=new HashSet<>();
set.addAll(list);
Comments
Just pass your list Collection to Hashset constructor and Get it back.
Then that one liner will be,
list = new ArrayList<E>(new HashSet<E>(list));
Comments
You can just put element into Set. Set keep unique values only.
List<String> list=new ArrayList<>();
Set<String> set=new HashSet<>();
set.addAll(list); // now you have unique value set
If you want to final result as unique value List just you need to get this Set as List
List<String> uniqueValList=new ArrayList<>(set);
answered Dec 5, 2013 at 9:21
Ruchira Gayan Ranaweera
35.7k17 gold badges78 silver badges117 bronze badges
Comments
You can use a Set but you will loose the original order of your list.
What you can do to keep the order is:
Set<E> copied = new HashSet<>();
List<E> res = new ArrayList<>();
for(E e : originalList) {
if(!copied.contains(e)) {
res.add(e);
}
copied.add(e);
}
Comments
The advice above to use Set is good - but if you need to keep the order just use a LinkedHashSet http://docs.oracle.com/javase/7/docs/api/java/util/LinkedHashSet.html
List<String> list = ...
Set<String> set = new LinkedHashSet<>(list);
list.clear();
list.addAll(set);
That will preserve order and remove all duplicates.
The result will be case sensitive though in the case of strings.