Question

java.lang.NumberFormatException: For input string: "null"

严重: Servlet.service() for servlet jsp threw exception
java.lang.NumberFormatException: For input string: "null"
at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
at java.lang.Integer.parseInt(Integer.java:449)
at java.lang.Integer.parseInt(Integer.java:499)
at org.apache.jsp.report.displayIndicatorData_jsp._jspService(displayIndicatorData_jsp.java:100)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:551)
at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:488)
at org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:968)
at org.apache.jsp.homeIndicator_jsp._jspService(homeIndicator_jsp.java:73)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.ApplicationDispatcher.invoke(ApplicationDispatcher.java:646)
at org.apache.catalina.core.ApplicationDispatcher.doInclude(ApplicationDispatcher.java:551)
at org.apache.catalina.core.ApplicationDispatcher.include(ApplicationDispatcher.java:488)
at org.apache.jasper.runtime.JspRuntimeLibrary.include(JspRuntimeLibrary.java:968)
at org.apache.jsp.home_005fCommon_jsp._jspService(home_005fCommon_jsp.java:270)
at org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:70)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:374)
at org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:342)
at org.apache.jasper.servlet.JspServlet.service(JspServlet.java:267)
)
这是我运行项目出现的异常，求各位大神看看

Answer 1

Servlet + jsp J2EE么？
空谈梁指针只有两个情况：1.对象空；2.值空了
我的猜测是：
你在页面提交了一个表单给servlet，类似如下的表单（简单写一下 ）
<form action="action.do" method="post">
<input type="text" name="test" />
</form>
后台servlet类中的代码要获取<input />标签输入的值
Integer test = Integer.parseInt(request.getParameter("test"));
时出现了异常
分析：含好运1.input标签里没写任何值就直接提交了，出现了值空；
2.input标签里的name值错了。

这是新手较常出现的错误，如果不是这样请你把具体的页面和后台代码发给我袜扰。比较利于大家帮你分析，web开发有些异常不是光看控制台打印就能解决的，需要自己分析。

Answer 2

错误是磨老 你想把一个 null 值 转换成数字
错误的页面是displayIndicatorData.jsp
报错信息碰游段是displayIndicatorData.jsp 被转换成servlet后的100行
此servlet如果是tomcat的会在work文件夹里一路点进去知道找到你发布的项目然后去相应路笑誉径下找
displayIndicatorData_jsp.java这个java类

Answer 3

String变搜绝哗量得到的是null，你进行Integer转换肯定报错了，在转换世行之前宏空，先判断一下变量是否为空

Answer 4

有"null"这样的数据埋闭燃转换成态消number类型了
debug一下就能查出原因弯虚了。

追问

如何在eclipse中debug，对于一个web项目

追答

启动的时候你选择的是 run as
debug时启动选择 debug as 就可以了

Answer 5

数字格式化异常,你传了个null进去