in Java, you can use a LinkedHashSet

in any language, you can do it yourself using a list (or vector) and a set in combination

Sorry for mistake in the first time!

You can use map to check if the element in the array or not and a vector array to save the elements.

map<int,int>mp;
vector<int>v;
for(int i=0;i<n;i++)
{ 
   if(mp[arr[i]]==0)
   {  
      mp[arr[i]] =1;
      v.push_back(arr[i]);
   }
}
for(int i=0;i<v.size();i++) cout<<v[i]<<" ";

And again sorry for my bad English!

As said above, you can actually use two data structures for the two properties you desire: one will maintain the order (vector with push_back), and the other will check for duplicates before inserting (set or unordered_set). Code for insertion will be something like this:

vector <int> order;
set <int> seen;

void insert (int element) {
    if (!seen.count (element)) {
        order.push_back (element);
        seen.insert (element);
    }
}