public V get(Object key) { Node<K,V> e; return (e = getNode(hash(key), key)) == null ? null : e.value; } final Node<K,V> getNode(int hash, Object key) { Node<K,V>[] tab; Node<K,V> first, e; int n; K k; //若是table數組不爲空 且 該鍵值對對應的位置存有node節點 if ((tab = table) != null && (n = tab.length) > 0 && (first = tab[(n - 1) & hash]) != null) { if (first.hash == hash && ((k = first.key) == key || (key != null && key.equals(k)))) return first; //若是table中存儲的鍵值對不是要查找的這對,就從該桶的鏈中查找 if ((e = first.next) != null) { if (first instanceof TreeNode) return ((TreeNode<K,V>)first).getTreeNode(hash, key); do { if (e.hash == hash && ((k= e.key) == key || (key != null && key.equals(k)))) return e; } while ((e = e.next) != null); } } return null;//該鍵值對不存在 }