JSP null pointer problem, a great god-CodePudding

<% @ page language="Java" contentType="text/HTML. Charset=utf-8 "
PageEncoding="utf-8" % & gt;

<meta charset="utf-8" & gt;
Insert the title here

<body>

<% @ page language="Java" contentType="text/HTML. Charset=utf-8 "
PageEncoding="utf-8" import="cc. Good" % & gt;
<% @ page import="Java. Util. *" % & gt;

<meta charset="utf-8" & gt;
Insert the title here

<body>
<% request. The setCharacterEncoding (" utf-8 ");
String goodname=request. The getParameter (" goodname ");
String price=request. The getParameter (" price ");
Good Good=new ();
Good. SetGoodname (goodname);
Good. SetPrice (price);
ArrayList & lt; Good> A=null;
The HttpSession sess=request. GetSession ();
If (session. The getAttribute (" good ")==null) {
A=new ArrayList (a);
} else {
A=(ArrayList) The session. The getAttribute (" good ");
}
A.a dd (good);
Sess. SetAttribute (" good ", a);
Response. SendRedirect (" NewFile2. JSP ");
% & gt;

<% @ page language="Java" contentType="text/HTML. Charset=utf-8 "
PageEncoding="utf-8" import="cc. Good" % & gt;
<% @ page import="Java. Util. *" % & gt;

<meta charset="utf-8" & gt;
Insert the title here

<body>

Name of commodity & lt;/td>	Commodity price & lt;/td>	Purchase & lt;/td>
Cell phones & lt;/td>	2000 & lt;/td>
TV & lt;/td>	5000 & lt;/td>
The washing machine & lt;/td>	3000 & lt;/td>
Air conditioning & lt;/td>	4000 & lt;/td>

<%! ArrayList 'arry;
Good Good [];
Int price; % & gt;
<%
The HttpSession ses=request. GetSession ();
'arry=(ArrayList) Ses. The getAttribute (" good ");
If (' arry!=null) {
for(int i=0; i<'arry. The size (); I++) {
Good [I]='arry. Get (I);
Price +=Integer. ParseInt (good [I]. GetPrice ());
Out.println (good [I] getGoodname ());
Out.println (good [I]. GetPrice ());
Out.println (" & lt; Br/& gt;" );
}
Out.println (" commodity price + price ");
}
% & gt;
<% %='arry & gt;

Great spirit, good [I]='arry. Get (I); Why is here to null pointer exception, how should solve

CodePudding user response:

'arry doesn't exist, not the object of sesssion,

Page link：https//www.codepudding.com/Backend/53102.html

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Name of commodity & lt;/td>

Commodity price & lt;/td>

Quantity & lt;/td>