使用sortedset和TreeSets。

import java.util.Arrays;

import java.util.SortedSet;

import java.util.TreeSet;
/*
n o w  j a v a  . c o m 提供
*/


public class Main 

{

   public static void main(String[] args)

   {

      // create TreeSet from array colors

      String[] colors = {"yellow", "green", "black", "tan", "grey",

         "white", "orange", "red", "green"};

      SortedSet<String> tree = new TreeSet<>(Arrays.asList(colors));
      /* 
      *来 自
       n o w j a v a . c o m
      */


      System.out.print("sorted set: ");

      printSet(tree);


      // get headSet based on "orange"

      System.out.print("headSet (\"orange\"):  ");

      printSet(tree.headSet("orange"));


      // get tailSet based upon "orange"

      System.out.print("tailSet (\"orange\"):  ");

      printSet(tree.tailSet("orange"));


      // get first and last elements

      System.out.printf("first: %s%n", tree.first());

      System.out.printf("last : %s%n", tree.last());

   }