Question

我用的是eclipse 建了一个servlet，覆盖init方法 运行的时候总是显示内部错误，如下：

HTTP Status 500 -

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type Exception report

message

description The server encountered an internal error () that prevented it from fulfilling this request.

exception

javax.servlet.ServletException: Servlet.init() for servlet LoginServlet threw exception
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845)
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
java.lang.Thread.run(Thread.java:619)

root cause

java.lang.NullPointerException
javax.servlet.GenericServlet.getServletContext(GenericServlet.java:160)
com.demo.LoginServlet.init(LoginServlet.java:32)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:286)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:845)
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:583)
org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:447)
java.lang.Thread.run(Thread.java:619)

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.18 logs.

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Apache Tomcat/6.0.18

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代码肯定是没错的，因为我在别人的电脑上试过，是可以运行的，不知道究竟哪里出错，请各位高手帮忙

Answer 1

init方法有两个，一个是带参数，一个是不带参数的，你应该覆盖不带参数的，如果非要覆盖带参数那个init方法，请在开头加入super。init（）；
回答完毕

追问

解决了，非常感谢~\(≧▽≦)/~
不过我还有个疑问，建servlet的时候选择覆盖init方法之后，它自动生成就是带参数的，要怎么覆盖不带参数的呢？？