SortedMap接口的使用-可排序接口

import java.util.Map;
import java.util.TreeMap;
import java.util.SortedMap;

public class SortedMapDemo
{

    public static void main(String args[])
    {

        SortedMap<String, String> map = null;

        map = new TreeMap<String, String>(); //通过子类实例化接口对象

        map.put("D", "DDDDD");

        map.put("A", "AAAAA");

        map.put("C", "CCCCC");

        map.put("B", "BBBBB");

        System.out.println("第一个元素的key:" + map.firstKey());

        System.out.println("key对的值为:" + map.get(map.firstKey()));

        System.out.println("最后一个元素的key:" + map.lastKey());

        System.out.println("key对的值为:" + map.get(map.lastKey()));

        System.out.println("返回小于指定规模的聚集（键值小于“C”）");

        for(Map.Entry<String, String> me:map.headMap("C").entrySet())
        {

            System.out.println("\t|- " + me.getKey() + "-->" + me.getValue());

        }

        System.out.println("返回大于指定规模的聚集（键值大于等于“C”）");

        for(Map.Entry<String, String> me:map.tailMap("C").entrySet())
        {

            System.out.println("\t|- " + me.getKey() + "-->" + me.getValue());

        }

        System.out.println("返回部份聚集（键值“B”和“D”之间,包含B不包含D）");

        for(Map.Entry<String, String> me:map.subMap("B", "D").entrySet())
        {

            System.out.println("\t|- " + me.getKey() + "-->" + me.getValue());

        }

    }

};

import java.util.Map;
import java.util.TreeMap;