Hashset HashMap和Hashtable 实例

package com.sky.collection;

import java.util.Enumeration;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.Iterator;
import java.util.Map;
import java.util.Set;
import java.util.Map.Entry;

public class HashDemo {

?/**
? * @param args
? */
?public static void main(String[] args) {
??// TODO Auto-generated method stub
??Set set = new HashSet();
??set.add(null);
??set.add("xiaowen");
??Iterator iterator=set.iterator();
??while(iterator.hasNext()){
???System.out.println("\n\t set中的数据："+iterator.next());
??}
??
??Map<String,String> map=new HashMap<String,String>();
??map.put("1", "xiaowen");
??map.put("2", "xiaoming");
??Iterator iter=map.entrySet().iterator();
??while(iter.hasNext()){
???Map.Entry entry = (Map.Entry) iter.next();
???Object obj=entry.getValue();
???Object obj2=entry.getKey();
???System.out.println("\n\t map中的数据:"+obj);
??}
??
??//或者: ???
//?? for (Iterator iter2 = map.keySet().iterator();iter2.hasNext();) {
//??? Object key = iter2.next();?
//??? Object val = map.get(key);
//??? System.out.println(key);
//??}
??
?? Hashtable<String,String> table=new Hashtable<String,String>();
?? table.put("1", "A");
?? table.put("2", "B");
?? table.put("3", "C");
?? Enumeration keys=table.keys();
?? while(keys.hasMoreElements()){
?? String key=(String)keys.nextElement();
?? System.out.println("\n\t table中的数据："+table.get(key));
?? }
??
?? Enumeration en= table.elements();
?? while(en.hasMoreElements()){
??? System.out.println("\n\t table 中的数据："+en.nextElement());
?? }

?}
}