public?void?doPost(HttpServletRequest?request,?HttpServletResponse?response)
			throws?ServletException,?IOException?{

		request.setCharacterEncoding("utf-8");
		
		Users?u?=?new?Users();
		String?username,mypassword,gender,email,introduce;
		boolean?isAccept;
		Date?birthday;
		String[]?favorites;
		
		
		SimpleDateFormat?sdf?=?new?SimpleDateFormat("yyyy-MM-dd");
		try
		{
			username?=?request.getParameter("username");
			mypassword?=?request.getParameter("mypassword");
			gender?=?request.getParameter("gender");
			email?=?request.getParameter("email");
			introduce?=?request.getParameter("introduce");
			birthday?=?sdf.parse(request.getParameter("birthday"));

			isAccept=request.getParameter("isAccept")!=null?true:false;
			//用來獲取多個復(fù)選按鈕的值
			favorites?=?request.getParameterValues("favorite");
			u.setUsername(username);
			u.setMypassword(mypassword);
			u.setGender(gender);
			u.setEmail(email);
			u.setFavorites(favorites);
			u.setIntroduce(introduce);
			u.setFlag(isAccept);
			u.setBirthday(birthday);
			
			//把注冊成功的用戶對象保存在session中
			request.getSession().setAttribute("regUser",?u);
			//跳轉(zhuǎn)到注冊成功頁面
			request.getRequestDispatcher("../userinfo.jsp").forward(request,response);
		}
		catch(Exception?ex)
		{
			ex.printStackTrace();
		}
		
		
	}

一下兩行代碼 為什么使用第二行代碼時不勾選復(fù)選框就會報(bào)空指針異常 而用第一行代碼就能夠正常返回false呢？ ?我的理解： 當(dāng)不勾選時request.getParameter("isAccept").equals("true")該表達(dá)式的值為假那么則返回false ?

?isAccept=request.getParameter("isAccept")!=null?true:false;

isAccept=request.getParameter("isAccept").equals("true")?true:false;