Getting last of LinkedHashSet

Question

I'd like to store a list of numbers 1,2,3,4 - (lets start with List<Integer>)

I'd like to make sure numbers are unique (ok, fine, Set<Integer>)

I'd like to guarantee order (ok ... LinkedHashSet<Integer>)

I'd like to get the last element from the list ..

What would be the simplest way to get the last number inserted into the LinkedHashSet<Integer> please?

Answer 1

There's no prebaked option for this. There's two off-the-cuff options, and neither are good:

The Order n approach:

public <E> E getLast(Collection<E> c) {     E last = null;     for(E e : c) last = e;     return last; } 

Yuck! But there's also an Order 1 approach:

class CachedLinkedHashSet<E> extends LinkedHashSet<E> {     private E last = null;      @Override     public boolean add(E e) {         last = e;         return super.add(e);     }     public E getLast() {         return last;     }  } 

This is off the cuff, so there might be a subtle bug in it, and for sure this isn't thread safe or anything. Your needs may vary and lead you to one approach over another.