java.util.Hashtable.keySet() 方法

package com.codingdict;

import java.util.*;

public class HashTableDemo {
   public static void main(String args[]) {

      // create hash table
      Hashtable htable1 = new Hashtable();      

      // put values in table
      htable1.put(1, "A");
      htable1.put(2, "B");
      htable1.put(3, "C");
      htable1.put(4, "D");

      // create a set view
      Set st = htable1.keySet();

      System.out.println("Display result: "+st);
   }    
}