The 'HashMap.put' has the code "if (e.hash == hash && eq(k, e.key))".
Do you think that the 'e.hash == hash' is required ?

I think that the "if (k == e.key || k.equals(e.key))" is proper.

For further details,
the following codes are parts of 'HashMap'.

<code>
public V put(K key, V value) {
   K k = maskNull(key);
   int hash = hash(k);
   int i = indexFor(hash, table.length);

   for (Entry<K,V> e = table[i]; e != null; e = e.next) {
       if (e.hash == hash && eq(k, e.key)) {  // #1
            V oldValue = e.value;
            e.value = value;
            e.recordAccess(this);
            return oldValue;
       }
   }
   ...

static int indexFor(int h, int length) {
   return h & (length-1);   // #2
}

static boolean eq(Object x, Object y) {
   return x == y || x.equals(y); // #3
}

</code>

The linked list of the 'table[i]' is heterogeneous with
hash value.  That is, when hash value of 'E0' is 5
and one of 'E1' is 6, both 'E0' and 'E1' can exist in
the same bucket 'table[i]' because of the above #2
( 00 & 10 = 00, 01 & 10 = 00).

But, it do not justify the code "if (e.hash == hash" of #1.

Because, ...

a) The functions of 'Map' puts/gets the value 'V' that is
mapped by the key 'K', not by the hash value.

b) The execution time of "k == e.key" by #3 is not large
than one of 'e.hash == hash'.

Therefore, I think,
The code "if (k == e.key || k.equals(e.key))" is proper
instead of #1.  #1 is overabundance.

I think that if there is overabundance in a library,
it means that the library is not optimised.

What is your opinion ?
Thanks.