从HashMap得到HashTable

import java.util.Enumeration;
import java.util.HashMap;
import java.util.Hashtable;

public class CreateHashTableFromHashMap {

public static void main(String[] args) {
    // TODO Auto-generated method stub
    HashMap hMap = new HashMap();
        hMap.put("1","One");
        hMap.put("2","Two");
        hMap.put("3","Three");
       
        Hashtable ht = new Hashtable();
       
        ht.put("1","This value would be REPLACED !!");
        ht.put("4","Four");
       
        System.out.println("Hashtable contents before copy");
        Enumeration e = ht.elements();
        while(e.hasMoreElements())
          System.out.println(e.nextElement());
       
        ht.putAll(hMap);
       
        System.out.println("Hashtable contents after copy");
        e = ht.elements();
        while(e.hasMoreElements())
          System.out.println(e.nextElement());
}

}
Console:
Hashtable contents before copy
Four
This value would be REPLACED !!
Hashtable contents after copy
Four
Three
Two
One