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求教大神java.lang.NullPointerException

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public void find(){
MyErrorMsg mem=null;
String name = request.getParameter("macc");
System.out.println(name+"namenamenamename");
try {
if(name.equals("")||name==null){
mem = new MyErrorMsg(0, "用户名不能为空");
}else{
mem =ms.find(name);//////////////////////////这一行报的异常
}
PrintWriter out;
response.setCharacterEncoding("utf-8");
response.setContentType("text/html;charset=utf-8");
out = response.getWriter();
String jsonStr = JSONObject.fromObject(mem).toString();
out.print(jsonStr);
out.flush();
out.close();
} catch (Exception e) {
e.printStackTrace();
}
}
}


IP属地:河南1楼2016-07-11 18:25回复
    我想调用service类的.find()方法,可老是报一个空指针异常,这个方法根本就进不去。不知道为啥


    IP属地:河南2楼2016-07-11 18:26
    回复
      2026-08-18 22:41:13
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      java.lang.NullPointerException
      at com.lrb.servlet.ManagerServlet.find(ManagerServlet.java:63)
      at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
      at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
      at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
      at java.lang.reflect.Method.invoke(Method.java:597)
      at com.lrb.servlet.ManagerServlet.service(ManagerServlet.java:38)
      at javax.servlet.http.HttpServlet.service(HttpServlet.java:722)
      at org.apache.catalina.core.ApplicationFilterChain.internalDoFilter(ApplicationFilterChain.java:306)
      at org.apache.catalina.core.ApplicationFilterChain.doFilter(ApplicationFilterChain.java:210)
      at org.apache.catalina.core.StandardWrapperValve.invoke(StandardWrapperValve.java:240)
      at org.apache.catalina.core.StandardContextValve.invoke(StandardContextValve.java:161)
      at org.apache.catalina.core.StandardHostValve.invoke(StandardHostValve.java:164)
      at org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:100)
      at org.apache.catalina.valves.AccessLogValve.invoke(AccessLogValve.java:550)
      at org.apache.catalina.core.StandardEngineValve.invoke(StandardEngineValve.java:118)
      at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:380)
      at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:243)
      at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:188)
      at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:288)
      at java.util.concurrent.ThreadPoolExecutor$Worker.runTask(ThreadPoolExecutor.java:886)
      at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:908)
      at java.lang.Thread.run(Thread.java:619)


      IP属地:河南4楼2016-07-11 18:27
      回复
        我知道了,是定义ms的时候没有实例化


        IP属地:河南5楼2016-07-11 18:39
        回复