老师为什么是 Emp e=map.get(key);为什么要用Emp呢

package com.imooc.db;
import java.util.HashMap;
import java.util.Map;
import com.imooc.bean.Emp;
public class DBUtil {
           public static Map<String,Emp> map=new HashMap<String,Emp>(); 
           static {
            map.put("101", new Emp("101","AA","123456","AA@imooc.com"));
            map.put("102", new Emp("102","BB","123456","BB@imooc.com"));
            map.put("103", new Emp("103","CC","123456","CC@imooc.com"));
            map.put("104", new Emp("104","DD","123456","DD@imooc.com"));
            map.put("105", new Emp("105","EE","123456","EE@imooc.com"));
           }
           
           //判断用户名和密码是否正确
           public static boolean selectEmpByAccountAndPassword(Emp emp) {
            boolean flag=false;
               for(String key:map.keySet()) {
             Emp e=map.get(key);
             if(emp.getAccount().equals(e.getAccount())&&emp.getPassword().equals(e.getPassword())){
              flag=true;
              break;
             }
            }
            return flag;
           }
          
}