java.lang.NullPointerException

Question

public class LoginUser {
@Resource(name = "userService")

private IUserService userService; public UserVO login(UserVO par_user) { try {
UserVO i = userService.findUser(par_user);


if (i.status.equals("id")) {
System.out.print("uName");
return i;
// return "欢迎用户："+uName;s
}else {
return i;
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
}
return null; }
} public UserVO findUser(UserVO user) {
// TODO Auto-generated method stub UserVO uservo = new UserVO();
long currentTime = System.currentTimeMillis();
d = new Date();
d.setTime(currentTime);
System.out.println(currentTime);
System.out.println("&&&&");
System.out.println(this.base64Encode(user.passWord.getBytes())); try {
uservo = this.userDao.findUser(user);
if (uservo != null) {
if (!(uservo.del_flg.equals("1"))) {
if (uservo.passWord.equals(this.base64Encode(user.passWord.getBytes()))) {
if (uservo.passwd_date == null) {
uservo.status = "第一次登陆，请修改密码";
} else if (d.compareTo(uservo.passwd_date) >= 0) {
uservo.status = "密码已经过期，请重新设置";
} else {
uservo.status = "id";
}
} else {
uservo.status = "该用户密码不正确，请重新输入";
}
} else {
uservo.status = "该用户已经删除";
}
} else {
uservo.status = "id不存在";
}
} catch (Exception e) {
// TODO Auto-generated catch block
e.printStackTrace();
} return uservo;
}
}初学java好多东西都不太懂，现在报错，错误如下，请高手们帮我看看吧，谢谢！
java.lang.NullPointerException
at com.hyron.service.UserServiceImpl.findUser(UserServiceImpl.java:76)
at com.hyron.action.LoginUser.login(LoginUser.java:17)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at flex.messaging.services.remoting.adapters.JavaAdapter.invoke(JavaAdapter.java:418)
at flex.messaging.services.RemotingService.serviceMessage(RemotingService.java:183)
at flex.messaging.MessageBroker.routeMessageToService(MessageBroker.java:1400)
at flex.messaging.endpoints.AbstractEndpoint.serviceMessage(AbstractEndpoint.java:1005)
at flex.messaging.endpoints.AbstractEndpoint$$FastClassByCGLIB$$1a3ef066.invoke(<generated>)
at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149)
at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:692)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
at org.springframework.flex.core.MessageInterceptionAdvice.invoke(MessageInterceptionAdvice.java:66)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.adapter.ThrowsAdviceInterceptor.invoke(ThrowsAdviceInterceptor.java:124)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.Cglib2AopProxy$FixedChainStaticTargetInterceptor.intercept(Cglib2AopProxy.java:576)
at flex.messaging.endpoints.AMFEndpoint$$EnhancerByCGLIB$$bf4d9873.serviceMessage(<generated>)
at flex.messaging.endpoints.amf.MessageBrokerFilter.invoke(MessageBrokerFilter.java:103)
at flex.messaging.endpoints.amf.LegacyFilter.invoke(LegacyFilter.java:158)
at flex.messaging.endpoints.amf.SessionFilter.invoke(SessionFilter.java:44)
at flex.messaging.endpoints.amf.BatchProcessFilter.invoke(BatchProcessFilter.java:67)
at flex.messaging.endpoints.amf.SerializationFilter.invoke(SerializationFilter.java:166)
at flex.messaging.endpoints.BaseHTTPEndpoint.service(BaseHTTPEndpoint.java:291)
at flex.messaging.endpoints.AMFEndpoint$$EnhancerByCGLIB$$bf4d9873.service(<generated>)
at org.springframework.flex.servlet.MessageBrokerHandlerAdapter.handle(MessageBrokerHandlerAdapter.java:101)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:771)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:716)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:560)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Unknown Source)
java.lang.NullPointerException
at com.hyron.action.LoginUser.login(LoginUser.java:20)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
at java.lang.reflect.Method.invoke(Unknown Source)
at flex.messaging.services.remoting.adapters.JavaAdapter.invoke(JavaAdapter.java:418)
at flex.messaging.services.RemotingService.serviceMessage(RemotingService.java:183)
at flex.messaging.MessageBroker.routeMessageToService(MessageBroker.java:1400)
at flex.messaging.endpoints.AbstractEndpoint.serviceMessage(AbstractEndpoint.java:1005)
at flex.messaging.endpoints.AbstractEndpoint$$FastClassByCGLIB$$1a3ef066.invoke(<generated>)
at net.sf.cglib.proxy.MethodProxy.invoke(MethodProxy.java:149)
at org.springframework.aop.framework.Cglib2AopProxy$CglibMethodInvocation.invokeJoinpoint(Cglib2AopProxy.java:692)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:150)
at org.springframework.flex.core.MessageInterceptionAdvice.invoke(MessageInterceptionAdvice.java:66)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.adapter.ThrowsAdviceInterceptor.invoke(ThrowsAdviceInterceptor.java:124)
at org.springframework.aop.framework.ReflectiveMethodInvocation.proceed(ReflectiveMethodInvocation.java:172)
at org.springframework.aop.framework.Cglib2AopProxy$FixedChainStaticTargetInterceptor.intercept(Cglib2AopProxy.java:576)
at flex.messaging.endpoints.AMFEndpoint$$EnhancerByCGLIB$$bf4d9873.serviceMessage(<generated>)
at flex.messaging.endpoints.amf.MessageBrokerFilter.invoke(MessageBrokerFilter.java:103)
at flex.messaging.endpoints.amf.LegacyFilter.invoke(LegacyFilter.java:158)
at flex.messaging.endpoints.amf.SessionFilter.invoke(SessionFilter.java:44)
at flex.messaging.endpoints.amf.BatchProcessFilter.invoke(BatchProcessFilter.java:67)
at flex.messaging.endpoints.amf.SerializationFilter.invoke(SerializationFilter.java:166)
at flex.messaging.endpoints.BaseHTTPEndpoint.service(BaseHTTPEndpoint.java:291)
at flex.messaging.endpoints.AMFEndpoint$$EnhancerByCGLIB$$bf4d9873.service(<generated>)
at org.springframework.flex.servlet.MessageBrokerHandlerAdapter.handle(MessageBrokerHandlerAdapter.java:101)
at org.springframework.web.servlet.DispatcherServlet.doDispatch(DispatcherServlet.java:771)
at org.springframework.web.servlet.DispatcherServlet.doService(DispatcherServlet.java:716)
at org.springframework.web.servlet.FrameworkServlet.processRequest(FrameworkServlet.java:644)
at org.springframework.web.servlet.FrameworkServlet.doPost(FrameworkServlet.java:560)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:637)
at javax.servlet.http.HttpServlet.service(HttpServlet.java:717)
at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:290)
at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:206)
at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:233)
at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:191)
at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:127)
at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:109)
at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
at org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
at java.lang.Thread.run(Unknown Source)

Answer 1

UserServiceImpl类的 76行代码 贴出来

Answer 2

uservo.status = "id不存在";
这个是76行的

Answer 3

   UserVO i = userService.findUser(par_user);
uservo.status = "id不存在";
说明uservoo查找不到！！所以会报空指针你的UserVo可能为null,你加上
if(i!=null){   
            if (i.status.equals("id")) {
                System.out.print("uName");
                return i;
}

Answer 4

查到的UserVO对象为空。所以在调用时就会报空指针。像楼上所说加个判断

Answer 5

恩，刚才别人帮我加了一行
uservo = new UserVO();
uservo.status = "id不存在";
现在不报错了，不过还是谢谢大家。这个分要怎么给，点哪个按钮？