import java.util.Hashtable;

import java.util.Set;

public class HashTableTest {

	public static void main(String args[]){

		Hashtable<String, String> ht = new Hashtable<String, String>();

		ht.put("one", "The first");

		ht.put("two", "The second");

		ht.put("three", "The third");

		Set<String> s = ht.keySet();

		for(String ss:s){

			System.out.println("Current hashtable element is: " + ss);

		}

	}

}

Person person1=new Person("zhangsan",20);

Person person2=new Person("lisi",21);

Person person3=new Person("wangwu",22);

Hashtable ht = new Hashtable();//不能Map ht=new Hashtable();若加强制转换后，后面方法不能用

ht.put("first", person1);

ht.put("second", person2);

ht.put("three", person3);

Enumeration e=ht.elements();

while(e.hasMoreElements()){

　　Person person=(Person)e.nextElement();

　　System.out.println(person.getName()+" "+person.getAge());

　}

import java.util.Map;

import java.util.HashMap;

import java.util.Iterator;

public class HashMapTest {

    public static void main(String args[]){

          Map map = new HashMap();

          map.put("Fruit1", "Apple");

          map.put("Fruit2", "Orange");

          map.put("Fruit3", "Pear");

          Iterator it = map.entrySet().iterator();

          while(it.hasNext()){

              Map.Entry entry = (Map.Entry)it.next();

	      Object key = entry.getKey();

              Object value = entry.getValue();

              System.out.println("Map key: " + key + " " + "Map value: " + value);

          }

    }

}

Map map = new HashMap();

Iterator iter = map.keySet().iterator();

while (iter.hasNext()) {

　　Object key = iter.next();

　　Object val = map.get(key);

}