hashtabledemo.java

测试哈希表

import java.util.*;

public class HashTableDemo{
    static  Hashtable hashTable=new Hashtable(); //为何用static
	public void init(){
		String roleList[]={"管理员","普通用户"};
		String codeList[]={"1001","1002"};
		for(int i=0;i<roleList.length;i++){
			hashTable.put(roleList[i],codeList[i]);
			}
		}
	public String getRight(String roleName){
		if(hashTable.containsKey(roleName))
		return (String)hashTable.get(roleName);
		else
		return null;	
		
		}
	public void insert(String roleName,String code){
		hashTable.put(roleName,code);
		}	
	public void delete(String roleName){
		if(hashTable.containsKey(roleName))
		hashTable.remove(roleName);		
		}
	public void update(String roleName,String code){
		if(hashTable.containsKey(roleName))
		hashTable.put(roleName,code);		
		}
	public void print(){
		Enumeration Ekey=hashTable.keys();
		while(Ekey.hasMoreElements()){
			String userName=Ekey.nextElement().toString();
			print(userName+""+this.getRight(userName));					
			}
		}
	public void print(Object oPara){    //此处Object用String代替也可
	System.out.println(oPara);
	}
    public static void main(String args[]){
    	HashTableDemo HT=new HashTableDemo();
    	HT.init();
    	HT.print();
    	HT.print("---------------------");
    	HT.insert("系统管理员","10003");
    	HT.print();
    	HT.print("----------------");
    	HT.update("系统管理员","10000");
    	HT.print();
    	HT.print("----------------------");
    	HT.delete("系统管理员");
    	HT.print();
    	}	
	
	
	}