Is it better to create a new HashSet or to reuse after invoking hashSet.clear()

Question

I want to process some new data in a HashSet, without any old data needed or the old HashSet object. The old HashSet object isn't referred to elsewhere.

Is it better to simply do hashset = new HashSet<String>() and let JVM to free the memory of the old HashSet object or should I call hashSet.clear() and reuse the same HashSet?

According to openJDK, hashSet.clear() is:

public void clear() {
    map.clear();
}

and map.clear() :

public void clear() {
     modCount++;
     Entry[] tab = table;
     for (int i = 0; i < tab.length; i++)
         tab[i] = null;
     size = 0;
 }

Since map.clear() iterates all the entries, will it be time consuming when the hashSet is large? Which one is recommended in this case, the constructor method or the clear() method?

Answer 1

Simple don't reference your HashSet anymore and let the garbage collector do the work.

Clearing the HashSet before dereferencing it does not free the memory any faster.