package agenda.data;import agenda.Exception.*;import java.util.*;/** * User List class * @author wc */public class UserList extends ArrayList<User>{    /**     * Check if the username is already exist     * @param uN UserName     * @throws agenda.Exception.UserExistException     */    public void isUserExist(String uN) throws UserExistException    {        for(User u:this)            if(u.userName.equals(uN))                throw new UserExistException(uN);    }        /**     * Check the username and password     * @param uN UserName     * @param pw Password     * @throws agenda.Exception.InvalidIDorPasswordException     */    public void checkUser(String uN, String pw) throws InvalidIDorPasswordException    {        boolean flag = false;        for(User u:this)            if(u.userName.equals(uN)&&u.password.equals(pw))                flag = true;        if(!flag) throw new InvalidIDorPasswordException();    }        /**     * Check the username     * @param uN UserName     * @throws agenda.Exception.InvalidIDorPasswordException     */    public void checkUser(String uN) throws InvalidIDorPasswordException    {        boolean flag = false;        for(User u : this)            if(u.userName.equals(uN))                flag = true;        if(!flag) throw new InvalidIDorPasswordException();    }}