读取数据库时有个错误，什么意思？怎么处理？

[黑兵]

HTTP Status 500 -

--------------------------------------------------------------------------------

type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

org.apache.jasper.JasperException: Index: 20, Size: 20
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:358)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)


root cause

java.lang.IndexOutOfBoundsException: Index: 20, Size: 20
java.util.ArrayList.RangeCheck(Unknown Source)
java.util.ArrayList.get(Unknown Source)
org.apache.jsp.ygda_005fmodi_jsp._jspService(ygda_005fmodi_jsp.java:108)
org.apache.jasper.runtime.HttpJspBase.service(HttpJspBase.java:133)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)
org.apache.jasper.servlet.JspServletWrapper.service(JspServletWrapper.java:311)
org.apache.jasper.servlet.JspServlet.serviceJspFile(JspServlet.java:301)
org.apache.jasper.servlet.JspServlet.service(JspServlet.java:248)
javax.servlet.http.HttpServlet.service(HttpServlet.java:856)


note The full stack trace of the root cause is available in the Tomcat logs.

上午还好使的，突然就不好使了。

[ladofwind]

好象是小标越界了,看看程序

[hq1305018]

程序中对一个ArrayList对象在执行get()方法时出现了异常，因为你要读取的20号元素不存在。

[ladofwind]

元素不存在。