注册到我的web应用程序java时出错
我有一个java web应用程序,允许用户搜索内容,当我尝试注册一个新用户时,我会收到以下消息注册到我的web应用程序java时出错,java,jsp,tomcat,servlets,Java,Jsp,Tomcat,Servlets,我有一个java web应用程序,允许用户搜索内容,当我尝试注册一个新用户时,我会收到以下消息 HTTP Status 500 – Internal Server Error Type Exception Report Description The server encountered an unexpected condition that prevented it from fulfilling the request. Exception java.lang.NullPointe
HTTP Status 500 – Internal Server Error
Type Exception Report
Description The server encountered an unexpected condition that prevented it from fulfilling the request.
Exception
java.lang.NullPointerException
DBConnector.queries.selectUserNamePass(queries.java:30)
Users.signupS.processRequest(signupS.java:42)
Users.signupS.doPost(signupS.java:109)
javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
javax.servlet.http.HttpServlet.service(HttpServlet.java:728)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)
有人知道如何解决吗?你有:
java.lang.NullPointerException
DBConnector.queries.selectUserNamePass(queries.java:30)
所以打开这门课。在第30行或之前放置断点。然后在调试模式下运行应用程序,按F8键逐步运行。您将找到导致NullPointerException的原因。有人知道如何解决它吗?即使看不到一点代码也很难帮助您。我们应该猜猜吗?