遍历Hashtable中的key和value的几种方法

遍历Hashtable中的key和value的几种方法

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package coreJava;

import java.util.Enumeration;
import java.util.Hashtable;
import java.util.Iterator;
/*
 * 处理原则:先取出key,再利用key获取value
 */
public class HashtableDemo {
    public static void main(String[] args) {
        Hashtable<String,String> ht = new Hashtable<String,String>();
        for(int i = 0;i<10;i++){
        ht.put("key"+i, "value"+i);
        }
        //利用循环遍历出key和value
        for(Iterator<String> itr = ht.keySet().iterator();itr.hasNext();){
            String key = (String)itr.next();
            String value = (String)ht.get(key);
            System.out.println(key+" (for) "+value);
        }
        //利用循环遍历出key和value
        Iterator<String> itr = ht.keySet().iterator();
        while (itr.hasNext()){
            String str = (String)itr.next();
            System.out.println(str+" (while) "+ht.get(str));
        }
        //利用枚举获取value
        Enumeration<String> e = ht.elements();
        while(e.hasMoreElements()){
            System.out.println(e.nextElement());
        }
        //利用枚举获取key:value对儿
        Enumeration<String> e2 = ht.keys();
        while(e2.hasMoreElements()){
            String key = e2.nextElement();
            System.out.println(key+" = "+ht.get(key));
        }
    }

}