java中Map的一個小示例，求指導

一個小程序 求指導！！！

import java.util.*;

/*
"RJ"	"01"	"zhangsan"
		"02"	"wangwu"

"XK"	"01"	"lisi"
		"02"	"xiaoer"
*/

public class Demo2
{
	public static void main(String[] args)
	{
		HashMap<String,HashMap<String,String>> zhuanYe = new HashMap<String,HashMap<String,String>>();

		HashMap<String,String> rj = new HashMap<String,String>();
		HashMap<String,String> xk = new HashMap<String,String>();

		zhuanYe.put("RJ",rj);
		zhuanYe.put("XK",xk);

		rj.put("01","zhangsan");
		rj.put("02","wangwu");

		xk.put("01","lisi");
		xk.put("02","xiaoer");

		System.out.println(rj);
		System.out.println(xk);

		showInfo(zhuanYe);
	}

	public static void showInfo(HashMap<String,HashMap<String,String>> hmer)
	{
		Iterator<String> it = hmer.keySet().iterator();

		while(it.hasNext())
		{
			String zyName = it.next();

			System.out.println(zyName);

			showStu(hmer.get(zyName));
		}
	}


	public static void showStu(HashMap<String,String> hm)
	{	
		Iterator<String> it = hm.keySet().iterator();

		while(it.hasNext())
		{
			String name = it.next();
			System.out.println(name + "....." + hm.get(name));
		}
	}

}