@Override public boolean containsKey(Object key){
  if (key == null) {
    return entryForNullKey != null;
  }
  int hash=key.hashCode();
  hash^=(hash >>> 20) ^ (hash >>> 12);
  hash^=(hash >>> 7) ^ (hash >>> 4);
  HashMapEntry<K,V>[] tab=table;
  for (HashMapEntry<K,V> e=tab[hash & (tab.length - 1)]; e != null; e=e.next) {
    K eKey=e.key;
    if (eKey == key || (e.hash == hash && key.equals(eKey))) {
      return true;
    }
  }
  return false;
}

@ Override public boolean containsKey ( Object key ) { if ( key == null ) { return entryForNullKey != null ; } int hash = key . hashCode ( ) ; hash ^= ( hash > > > 20 ) ^ ( hash > > > 12 ) ; hash ^= ( hash > > > 7 ) ^ ( hash > > > 4 ) ; HashMapEntry < K , V > [ ] tab = table ; for ( HashMapEntry < K , V > e = tab [ hash & ( tab . length - 1 ) ] ; e != null ; e = e . next ) { K eKey = e . key ; if ( eKey == key || ( e . hash == hash && key . equals ( eKey ) ) ) { return true ; } } return false ; }
returns whether this map contains the specified key .
