[Java] Java中HashMap里面key为null存放到哪

// HashMap的put方法
 public V put(K key, V value) {
  if (table == EMPTY_TABLE) {
    inflateTable(threshold);
  }
  if (key == null)
     // key为null调用putForNullKey(value)
     return putForNullKey(value);
  int hash = hash(key);
  int i = indexFor(hash, table.length);
  for (Entry<K,V> e = table[i]; e != null; e = e.next) {
    Object k;
    if (e.hash == hash && ((k = e.key) == key || key.equals(k))) {
    V oldValue = e.value;
    e.value = value;
    e.recordAccess(this);
    return oldValue;
    }
  }
 
  modCount++;
  addEntry(hash, key, value, i);
  return null;
  }

/**
  * Offloaded version of put for null keys
  */
 private V putForNullKey(V value) {
   for (Entry<K,V> e = table[0]; e != null; e = e.next) {
   if (e.key == null) {
     V oldValue = e.value;
     e.value = value;
     e.recordAccess(this);
     return oldValue;
   }
   }
   modCount++;
   addEntry(0, null, value, 0);
   return null;
 }