报错信息
二月 06, 2017 3:03:51 下午 org.apache.catalina.core.StandardWrapperValve invoke
SEVERE: Servlet.service() for servlet [BillSevlet] in context with path [/smbms] threw exception
java.lang.NullPointerException
at java.math.BigDecimal.<init>(Unknown Source)
at cn.smbms.servlet.BillSevlet.add(BillSevlet.java:168)
at cn.smbms.servlet.BillSevlet.doPost(BillSevlet.java:53)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:305)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
at cn.smbms.filter.CharacterEncoding.doFilter(CharacterEncoding.java:26)
请问一下这段报错信息是什么意思