Does HashMap.clear() resize inner hash table to the original size?

Question

What happens to the HashMap after this code execution?

HashMap m  = new HashMap();
for (int i = 0; i < 1024 * 1024; i++)
    m.put(i, i);
m.clear();

After 1M puts the inner hash table will grow from original 16 to 1MB. Does clear() resize it to the original size or not?

Answer 1

No. The table retains its size. All elements are set to null:

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

Answer 2

This is an implementation detail, and I don't know what API you're reading that says anything about 1M puts or an inner hash table.

Let's just look at an implementation:

  620       /**
  621        * Removes all of the mappings from this map.
  622        * The map will be empty after this call returns.
  623        */
  624       public void clear() {
  625           modCount++;
  626           Entry[] tab = table;
  627           for (int i = 0; i < tab.length; i++)
  628               tab[i] = null;
  629           size = 0;
  630       }

http://www.docjar.com/html/api/java/util/HashMap.java.html#621

So the OpenJDK 7 implementation does not restore the original size.