HashTable的五種遍歷方式

package com.xing.lab.util;

import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Map;
import java.util.Map.Entry;


public class TraverseHashTable {
    public static void main(String[] args) {
        Hashtable<String, String> hashtable = new Hashtable<String, String>();
        hashtable.put("1", "aa");
        hashtable.put("2", "bb");
        hashtable.put("3", "cc");

        //第一種hashtable遍歷方式
        System.out.println("第一種遍歷方式");

        for (Iterator<String> iterator = hashtable.keySet().iterator();iterator.hasNext();) {
            String key = iterator.next();
            System.out.println("key-----" + key);
            System.out.println("value--------" + hashtable.get(key));
        }

        //第二種hashtable遍歷方式
        System.out.println("第二種遍歷方式");

        for (Iterator<Entry<String, String>> iterator = hashtable.entrySet().iterator();
                iterator.hasNext();) {
            Entry<String, String> entry = iterator.next();
            System.out.println("key---------" + entry.getKey());
            System.out.println("value------------" + entry.getValue());
        }

        //第三種hashtable遍歷方式
        System.out.println("第三種遍歷方式");

        for (Map.Entry<String, String> entry : hashtable.entrySet()) {
            System.out.println("key---------" + entry.getKey());
            System.out.println("value--------" + entry.getValue());
        }

        //第四種遍歷方式
        System.out.println("第四種遍歷方式");

        Enumeration<String> e = hashtable.keys();

        while (e.hasMoreElements()) {
            String key = e.nextElement();
            System.out.println("key-----" + key);
            System.out.println("value-------" + hashtable.get(key));
        }

        //第五中遍歷方式(獲取全部的值)
        System.out.println("第五種遍歷方式");

        Enumeration<String> e2 = hashtable.elements();

        while (e2.hasMoreElements()) {
            String string = (String) e2.nextElement();
            System.out.println(string);
        }
    }
}