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问题描述
这是我的代码:
JSP 页面
<%@page contentType="text/html" pageEncoding="UTF-8"%> <!DOCTYPE html> <html> <head> <meta http-equiv="Content-Type" content="text/html; charset=UTF-8"> <title>JSP Page</title> </head> <body> <h1><center>Web Site Analizer</center></h1> <br/> <form action=localhost:8080/WebSiteAnalizer/SiteAnalizer method=post> Enter the Percentage (0-100): <input type="Text" id="percentage"> <br/><br/><br/> Enter the Words (Separated from New Line (/n)): <br/> <textarea id='wordList' value='wordList'></textarea> <br/><br/> <input type="submit" value="Submit"> </form> </body> </html>Servlet
public void doPost(HttpServletRequest request, HttpServletResponse response)throws ServletException, IOException { String[] listOfWords = request.getParameter("wordList").toLowerCase().trim().split(" "); //Get the List of words int percentage = Integer.parseInt(request.getParameter("percentage")); // Get the percentage value int numberOfWordsInProgramHash = 0; //Keep tracks of how many words in "program" per webpage int primaryKey = 0; //Store the primary key }当我运行这个应用程序时,我得到了 NullPointerException.以下是完整错误
I get the NullPointerException, when I run this application. Below is the full error
java.lang.NullPointerException SiteAnalizer.doPost(SiteAnalizer.java:40) javax.servlet.http.HttpServlet.service(HttpServlet.java:641) javax.servlet.http.HttpServlet.service(HttpServlet.java:722)第 40 行是
String[] listOfWords = request.getParameter("wordList").toLowerCase().trim().split(" "); //Get the List of words这段代码有什么问题?
推荐答案使用 name 属性代替 id 属性
Use the name attribute instead of the id attribute
<input type="Text" name="percentage">和
<textarea name='wordList' value='wordList'>阅读:表单简介
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NullPointerException,读取 HTML 输入时
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