java集合TreeMap、Hashtable

package ca.map;

import java.util.Comparator;
import java.util.Enumeration;
import java.util.HashMap;
import java.util.Hashtable;
import java.util.LinkedList;
import java.util.TreeMap;

public class TreeMapDome {
    //1、TreeMap如不指定排序器，默认将按照key值进行升序排序，如果指定了排序器，则按照指定的排序器进行排序。
    //2、具体的排序规则，开发人员可以在int compare()方法中进行指定。
    public static void main(String[] args) {
        //不指定排序器
        TreeMap<String, String> stm =  new TreeMap<String, String>();
        stm.put("2", "22");
        stm.put("b", "BB");
        stm.put("1","11");
        stm.put("a", "AA");
        TreeMap<String, String> stm1 =  new TreeMap<String, String>();
        stm1.put("2", "22");
        stm1.put("b", "BB");
        stm1.put("1","11");
        stm1.put("a", "AA");
        System.out.println(stm1.equals(stm));
        System.out.println(stm==stm1);
        System.out.println(stm.hashCode());
        System.out.println(stm1.hashCode());
        System.out.println("TreeMapSortByDefault:"+stm1);
        System.out.println();
        TreeMap<String, String> stm2 = new TreeMap<String, String>(new Comparator<String>() {
            /* 
             * int compare(Object o1, Object o2) 返回一个基本类型的整型， 
             * 返回负数表示：o1 小于o2， 
             * 返回0 表示：o1和o2相等， 
             * 返回正数表示：o1大于o2。 
             */ 
            public int compare(String o1, String o2) {
              //指定排序器按照降序排列 
                return o2.compareTo(o1);
            }
        });
        stm2.put("2", "22");
        stm2.put("b", "BB");
        stm2.put("1","11");
        stm2.put("a", "AA");
        System.out.println("TreeMapSortByDefaul2t:"+stm2);
        Hashtable<String,String> htb = new Hashtable<String, String>();
        htb.put("1", "aa");
        htb.put("2", "bb");
        htb.put("3", "cc");
        System.out.println("hash table:"+htb);
        System.out.println();
        //参数initialCapacity是Hashtable的初始容量，它的值应大于0。loadFactor又称装载因子，是一个0.0到0.1之间的float型的浮点数。它是一个百分比，表明了哈希表何时需要扩充
        Hashtable<String, String> hashTB = new Hashtable<String, String>(5, 0.7f);
        hashTB.put("1", "beijing");
        hashTB.put("2", "tianjing");
        hashTB.put("3", "lanzhou");
        Enumeration enumer = hashTB.elements();
        while(enumer.hasMoreElements()){
            String s = (String) enumer.nextElement();
            System.out.print(s+"  ");
        }
    }
}

输出为：

true
false
7398
7398
TreeMapSortByDefault:{1=11, 2=22, a=AA, b=BB}


TreeMapSortByDefaul2t:{b=BB, a=AA, 2=22, 1=11}
hash table:{3=cc, 2=bb, 1=aa}


beijing  lanzhou  tianjing