Hashtable基本用法概述

来源：互联网发布：php是什么意思啊编辑：程序博客网时间：2024/05/17 11:07

http://cofounder.blog.163.com/blog/static/21243321920129194515451/

以哈希表的形式存储数据,数据的形式是键值对.特点:查找速度快,遍历相对慢键值不能有空指针和重复数据创建Hashtable<Integer,String> ht=new Hashtable<Integer,String>();添值ht.put(1,"Andy");ht.put(2,"Bill");ht.put(3,"Cindy");ht.put(4,"Dell");ht.put(5,"Felex");ht.put(6,"Edinburg");ht.put(7,"Green");取值String str=ht.get(1);System.out.println(str);// Andy对键进行遍历Iterator it = ht.keySet().iterator();while (it.hasNext()) {    Integer key = (Integer)it.next();    System.out.println(key);}对值进行遍历Iterator it = ht.values().iterator();while (it.hasNext()) {    String value =(String) it.next();    System.out.println(value);}取Hashtable记录数Hashtable<Integer,String> ht=new Hashtable<Integer,String>();ht.put(1,"Andy");ht.put(2,"Bill");ht.put(3,"Cindy");ht.put(4,"Dell");ht.put(5,"Felex");ht.put(6,"Edinburg");ht.put(7,"Green");int i=ht.size();// 7删除元素Hashtable<Integer,String> ht=new Hashtable<Integer,String>();ht.put(1,"Andy");ht.put(2,"Bill");ht.put(3,"Cindy");ht.put(4,"Dell");ht.put(5,"Felex");ht.put(6,"Edinburg");ht.put(7,"Green");ht.remove(1);ht.remove(2);ht.remove(3);ht.remove(4);System.out.println(ht.size());// 3Iterator it = ht.values().iterator();while (it.hasNext()) {        // Get value    String value =(String) it.next();    System.out.println(value);}输出:3GreenEdinburgFelex

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