详解Java8 HashMap扩容算法

final Node<K,V>[] resize() {
  // ...省略不重要的
}

for (int j = 0; j < oldCap; ++j) {
  Node<K,V> e;
  if ((e = oldTab[j]) != null) {
    oldTab[j] = null;
    if (e.next == null)
      newTab[e.hash & (newCap - 1)] = e;
    else if (e instanceof TreeNode)
      ((TreeNode<K,V>)e).split(this, newTab, j, oldCap);
    else { // preserve order
      Node<K,V> loHead = null, loTail = null;
      Node<K,V> hiHead = null, hiTail = null;
      Node<K,V> next;
      do {
        next = e.next;
        if ((e.hash & oldCap) == 0) {
          if (loTail == null)
            loHead = e;
          else
            loTail.next = e;
          loTail = e;
        }
        else {
          if (hiTail == null)
            hiHead = e;
          else
            hiTail.next = e;
          hiTail = e;
        }
      } while ((e = next) != null);
      if (loTail != null) {
        loTail.next = null;
        newTab[j] = loHead;
      }
      if (hiTail != null) {
        hiTail.next = null;
        newTab[j + oldCap] = hiHead;
      }
    }
  }
}
 
 
final V putVal(int hash, K key, V value, boolean onlyIfAbsent, boolean evict) {
  // ...省略不重要的
  if ((p = tab[i = (n - 1) & hash]) == null)
    tab[i] = newNode(hash, key, value, null);
  else {
  // ...省略不重要的
}