500 Servlet Exception

[show] java.lang.NumberFormatException: For input string: ""

java.lang.NumberFormatException: For input string: ""
	at java.lang.NumberFormatException.forInputString(NumberFormatException.java:48)
	at java.lang.Integer.parseInt(Integer.java:468)
	at java.lang.Integer.parseInt(Integer.java:497)
	at _jsp._article._detail__jsp._jspService(article/detail.jsp:114)
	at com.caucho.jsp.JavaPage.service(JavaPage.java:61)
	at com.caucho.jsp.Page.pageservice(Page.java:587)
	at com.caucho.server.dispatch.PageFilterChain.doFilter(PageFilterChain.java:195)
	at com.caucho.server.webapp.DispatchFilterChain.doFilter(DispatchFilterChain.java:97)
	at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:265)
	at com.caucho.server.webapp.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:293)
	at com.caucho.server.webapp.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:111)
	at org.apache.struts.action.RequestProcessor.doForward(RequestProcessor.java:1063)
	at org.apache.struts.action.RequestProcessor.processForwardConfig(RequestProcessor.java:386)
	at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:229)
	at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194)
	at org.apache.struts.action.ActionServlet.doGet(ActionServlet.java:414)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:114)
	at javax.servlet.http.HttpServlet.service(HttpServlet.java:91)
	at com.caucho.server.dispatch.ServletFilterChain.doFilter(ServletFilterChain.java:103)
	at com.caucho.server.webapp.DispatchFilterChain.doFilter(DispatchFilterChain.java:97)
	at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:265)
	at com.caucho.server.webapp.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:293)
	at com.caucho.server.webapp.RequestDispatcherImpl.forward(RequestDispatcherImpl.java:111)
	at org.tuckey.web.filters.urlrewrite.NormalRewrittenUrl.doRewrite(NormalRewrittenUrl.java:195)
	at org.tuckey.web.filters.urlrewrite.RuleChain.handleRewrite(RuleChain.java:159)
	at org.tuckey.web.filters.urlrewrite.RuleChain.doRules(RuleChain.java:141)
	at org.tuckey.web.filters.urlrewrite.UrlRewriter.processRequest(UrlRewriter.java:90)
	at org.tuckey.web.filters.urlrewrite.UrlRewriteFilter.doFilter(UrlRewriteFilter.java:417)
	at com.caucho.server.dispatch.FilterFilterChain.doFilter(FilterFilterChain.java:87)
	at com.caucho.server.webapp.WebAppFilterChain.doFilter(WebAppFilterChain.java:187)
	at com.caucho.server.dispatch.ServletInvocation.service(ServletInvocation.java:265)
	at com.caucho.server.http.HttpRequest.handleRequest(HttpRequest.java:273)
	at com.caucho.server.port.TcpConnection.run(TcpConnection.java:682)
	at com.caucho.util.ThreadPool$Item.runTasks(ThreadPool.java:730)
	at com.caucho.util.ThreadPool$Item.run(ThreadPool.java:649)
	at java.lang.Thread.run(Thread.java:619)