完全的小白请教下这种错误怎么回事
三千烦梦 2019-02-14 05:34:32 Root Cause
java.lang.NullPointerException
com.core.ConnDB.executeQuery(ConnDB.java:53)
com.dao.ManagerDAO.checkManager(ManagerDAO.java:73)
com.action.Manager.managerLogin(Manager.java:51)
com.action.Manager.execute(Manager.java:24)
org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:419)
org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:224)
org.apache.struts.action.ActionServlet.process(ActionServlet.java:1194)
org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:432)
javax.servlet.http.HttpServlet.service(HttpServlet.java:661)
javax.servlet.http.HttpServlet.service(HttpServlet.java:742)
org.apache.tomcat.websocket.server.WsFilter.doFilter(WsFilter.java:52)