运行java程序时出现的错误:" java.lang.NullPointerException”
各位高手,我用jsp+javabean编写代码,总是出现java.lang.NullPointerException。错误如下:
java.lang.NullPointerException
at dbase.Dbconn.getpreparedStatement(Dbconn.java:64)
at action.UserLogin.loginck(UserLogin.java:37)
at servlet.UserLoginServlet.doGet(UserLoginServlet.java:69)
at servlet.UserLoginServlet.doPost(UserLoginServlet.java:28)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:647)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:729)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:269)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:188)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:213)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:172)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:117)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:108)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:174)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:879)
at org.apache.coyote.http11.Http11BaseProtocol$Http11ConnectionHandler.processConnection(Http11BaseProtocol.java:665)
at org.apache.tomcat.util.net.PoolTcpEndpoint.processSocket(PoolTcpEndpoint.java:528)
at org.apache.tomcat.util.net.LeaderFollowerWorkerThread.runIt(LeaderFollowerWorkerThread.java:81)
at org.apache.tomcat.util.threads.ThreadPool$ControlRunnable.run(ThreadPool.java:689)
at java.lang.Thread.run(Thread.java:619)
其中用红字标出的错误在原文中要么是注释部分,要么是我屏蔽掉的部分。然后我就把那些全给删了,但是还是显示如上所示的错误,我真是不知道该怎么办了。望各位大哥大姐们帮帮忙,不甚感激,好几天了都!!高手救命呀!!
其中第二行异常在原文中是一个没有任何文字的行;
第四行异常在原文中对应的代码是“response.sendRedirect("/abc/login.jsp");”