當沒選擇checkbox的時候老師的代碼成功進入循環(huán)體，我改了個順序就報錯了-----------------------------------------------String[] isUseCookies = request.getParameterValues("isUseCookie");? ? ? ?if(isUseCookies!=null&&isUseCookies.length>0)老師寫的成功了-----------------------------------------------?String[] isUseCookies = request.getParameterValues("isUseCookie");? ? ? ?if(isUseCookies.length>0&&isUseCookies!=null)這樣寫就報空指針錯誤了，why???-----------------------------------------------org.apache.jasper.JasperException: An exception occurred processing JSP page /dologin.jsp at line 3532: ? ? ? ?request.setCharacterEncoding("utf-8");33: ? ? ? ?//棣栧厛鍒ゆ柇鐢ㄦ埛鏄惁閫夋嫨浜嗚浣忕櫥褰曠姸鎬?34: ? ? ? ?String[] isUseCookies = request.getParameterValues("isUseCookie");35: ? ? ? ?if(isUseCookies.length>0&&isUseCookies!=null)36: ? ? ? ?{37: ? ? ? ? ? //鎶婄敤鎴峰悕鍜屽瘑鐮佷繚瀛樺湪Cookie瀵硅薄閲岄潰38: ? ? ? ? ? String username = URLEncoder.encode(request.getParameter("username"),"utf-8");