java.lang.NullPointerException: Cannot invoke "java.sql.Connection.prepareStatement(String)" because "con" is null at edu.illinois.webservices.systemscreen.BaseSystemScreenFactory2.getSystemScreen(BaseSystemScreenFactory2.java:341) at edu.illinois.webservices.systemscreen.SystemScreenFactory2.transform(SystemScreenFactory2.java:192) at edu.illinois.webservices.systemscreen.SystemScreenFactory2.transform(SystemScreenFactory2.java:106) at edu.illinois.webservices.blog.servlet.ViewServlet.doPost(ViewServlet.java:357) at edu.illinois.webservices.blog.servlet.ViewServlet.doGet(ViewServlet.java:66) at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:564) at jakarta.servlet.http.HttpServlet.service(HttpServlet.java:658) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:195) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) at org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:51) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) at org.apache.catalina.filters.SetCharacterEncodingFilter.doFilter(SetCharacterEncodingFilter.java:115) at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:164) at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:140) at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:167) at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:90) at org.apache.catalina.authenticator.AuthenticatorBase.invoke(AuthenticatorBase.java:483) at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:115) at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:93) at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:74) at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:344) at org.apache.coyote.ajp.AjpProcessor.service(AjpProcessor.java:431) at org.apache.coyote.AbstractProcessorLight.process(AbstractProcessorLight.java:63) at org.apache.coyote.AbstractProtocol$ConnectionHandler.process(AbstractProtocol.java:905) at org.apache.tomcat.util.net.NioEndpoint$SocketProcessor.doRun(NioEndpoint.java:1741) at org.apache.tomcat.util.net.SocketProcessorBase.run(SocketProcessorBase.java:52) at org.apache.tomcat.util.threads.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1190) at org.apache.tomcat.util.threads.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:659) at org.apache.tomcat.util.threads.TaskThread$WrappingRunnable.run(TaskThread.java:63) at java.base/java.lang.Thread.run(Thread.java:840)