TreeMap and TreeSet

TreeMap implements the SortedMap interface, which means that the key elements in the Map are sorted in the order of size, and the key size can be judged by their natural order (natural Ordering), can also be constructed by passing in the comparator (Comparator). The TreeMap Bottom is realized by the red and black trees (red-black tree), which means,,, containsKey() get() put() remove() All log(n) of the time complexity.

The TreeMap is non-synchronous (not synchronized) and can be packaged in sync if you need to use it in a multithreaded environment:

    SortedMap m = Collections.synchronizedSortedMap(new TreeMap(...));  

The iterator returned by the iterator method of the TreeMap is fail-fast.

The TreeMap constructor

// The default constructor. Using this constructor, the elements in the TreeMap are arranged in natural order.  TreeMap ()//  created TreeMap contains mapextendsextends v> copyFrom)  //  Specify the tree's comparator Super k> Comparator)//  The TreeSet created contains copyFromextends v> copyFrom)

TreeMap and TreeSet