求助 空指针异常原因。

[一起喝芬达2010]

[code=java]十二月 30, 2017 5:21:22 下午 org.apache.catalina.connector.CoyoteAdapter service
SEVERE: An exception or error occurred in the container during the request processing
java.lang.NullPointerException
	at org.apache.catalina.connector.Request.getServletContext(Request.java:1541)
	at org.apache.catalina.connector.CoyoteAdapter.postParseRequest(CoyoteAdapter.java:636)
	at org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:398)
	at org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:249)
	at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:267)
	at org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:245)
	at org.apache.tomcat.util.net.JIoEndpoint$SocketProcessor.run(JIoEndpoint.java:260)
	at java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1145)
	at java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:615)
	at java.lang.Thread.run(Thread.java:722)

[/code]

代码如上， 可以运行。就是时不时出现如上错误提示，看着不爽，本人萌新，希望大神们给个思路排错

[自由自在_Yu]

定位一下，找到报空指针异常的那一行，判断是哪一个对象为null了 if(object != null){ //执行的时候判断一下，不为null再继续执行 }

[有颗大白菜]

出现这个的原因是因为你没有对有可能为空的字段做数值为空的判断