红黑树是一个更高效的检索二叉树，因此常常用来实现关联数组。典型地，JDK提供的集合类TreeMap本身就是一个红黑树的实现。-Red-black tree is a binary tree search more efficient, so often used to implement associative arrays. Typically, JDK provides a collection of classes TreeMap itself is a red-black tree implementation.