java.lang.NullPointerException 解决方法

java.lang.NullPointerException at com.sinosoft.visa.ui.control.viewhelper.RecycleRegistInputViewHelper.requestToDtoList(RecycleRegistInputViewHelper.java:123) at com.sinosoft.visa.ui.control.facade.UIRecycleRegistSaveFacade.execute(UIRecycleRegistSaveFacade.java:147) at org.apache.struts.action.RequestProcessor.processActionPerform(RequestProcessor.java:421) at org.apache.struts.action.RequestProcessor.process(RequestProcessor.java:226) at org.apache.struts.action.ActionServlet.process(ActionServlet.java:1169) at org.apache.struts.action.ActionServlet.doPost(ActionServlet.java:415) at javax.servlet.http.HttpServlet.service(HttpServlet.java:727) at javax.servlet.http.HttpServlet.service(HttpServlet.java:820) at weblogic.servlet.internal.StubSecurityHelper$ServletServiceAction.run(StubSecurityHelper.java:227) at weblogic.servlet.internal.StubSecurityHelper.invokeServlet(StubSecurityHelper.java:125) at weblogic.servlet.internal.ServletStubImpl.execute(ServletStubImpl.java:292) at weblogic.servlet.internal.TailFilter.doFilter(TailFilter.java:26) at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42) at com.sinosoft.visa.utility.ui.control.action.SessionFilter.doFilter(SessionFilter.java:87) at weblogic.servlet.internal.FilterChainImpl.doFilter(FilterChainImpl.java:42) at weblogic.servlet.internal.WebAppServletContext$ServletInvocationAction.run(WebAppServletContext.java:3496) at weblogic.security.acl.internal.AuthenticatedSubject.doAs(AuthenticatedSubject.java:321) at weblogic.security.service.SecurityManager.runAs(Unknown Source) at weblogic.servlet.internal.WebAppServletContext.securedExecute(WebAppServletContext.java:2180) at weblogic.servlet.internal.WebAppServletContext.execute(WebAppServletContext.java:2086) at weblogic.servlet.internal.ServletRequestImpl.run(ServletRequestImpl.java:1406) at weblogic.work.ExecuteThread.execute(ExecuteThread.java:201) at weblogic.work.ExecuteThread.run(ExecuteThread.java:173) 这是什么意思？怎么解决？

有个对象是null，系统使用到这对象时报错。

自己解决了，安装sql server2000 sp3。