不知道错在哪里？

package service;


import User.User;

/*
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import com.ibatis.dao.client.DaoException;
import java.sql.SQLException;
import javax.xml.rpc.ServiceException;
/**
 *
 * @author Administrator
 */
public class  UserService {
    private static User user = new User();
   
    public static User login(String UserCode, String UserPwd) throws DaoException, SQLException, ServiceException{
        return checkSystemUser(UserCode,UserPwd);
    }
   
    private static  User checkSystemUser(String UserCode,String UserPwd) throws DaoException, SQLException, ServiceException
    {
        User loginUser = UserService.getUserByCode(UserCode);
        if(loginUser==null)
            throw new ServiceException("用户不存在");
        String pwd=loginUser.getUserPwd();
        if((pwd)!=0)
            throw new ServiceException("密码不正确");
        return loginUser;         
    }
   
    private static User getUserByID(int id) throws DaoException, SQLException, ServiceException
    {
        User loginUser=user.findById(id);        
        if(loginUser==null)
            throw new ServiceException("用户没有找到");
        return loginUser;
        
    }
   
    private static User getUserByCode(String UserCode) throws DaoException, SQLException, ServiceException
    {
         User loginUser=user.findById(UserCode);         
         if(loginUser==null)
             throw new ServiceException("用户不存在");
         return loginUser;
    }
}


这是我项目里面的一个文件，搞不懂为什么红色部分总提示出错？