java 500 空指针问题

浏览是这样的
type Exception report

message

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

exception

javax.servlet.ServletException: Wrapper cannot find servlet class com.linkaibo.Httpsevlet.HelloWorldServlet or a class it depends on
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
java.lang.Thread.run(Thread.java:722)

root cause

java.lang.ClassNotFoundException: com.linkaibo.Httpsevlet.HelloWorldServlet
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1645)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1491)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
java.lang.Thread.run(Thread.java:722)

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.29 logs. --------------------编程问答-------------------- 抛出异常的信息是，无法找到这个包class com.linkaibo.Httpsevlet.Hello中的类，你再检查一下 --------------------编程问答-------------------- 这哪是空指针，没代码不好确定，从错误来看就是楼上说的 --------------------编程问答-------------------- --------------------编程问答-------------------- 简单点说就是代码错误！好好找找啊 --------------------编程问答-------------------- com.linkaibo.Httpsevlet.HelloWorldServlet 这个类有错 或没编译 检查一下 --------------------编程问答-------------------- 代码错了！ --------------------编程问答-------------------- java.lang.ClassNotFoundException: com.linkaibo.Httpsevlet.HelloWorldServlet
ClassNotFoundException --------------------编程问答-------------------- description The server encountered an internal error () that prevented it from fulfilling this request.

exception

<div color=red>javax.servlet.ServletException: Wrapper cannot find servlet class com.linkaibo.Httpsevlet.HelloWorldServlet or a class it depends on</div>
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
java.lang.Thread.run(Thread.java:722)

root cause

java.lang.ClassNotFoundException: com.linkaibo.Httpsevlet.HelloWorldServlet
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1645)
org.apache.catalina.loader.WebappClassLoader.loadClass(WebappClassLoader.java:1491)
org.apache.catalina.valves.ErrorReportValve.invoke(ErrorReportValve.java:102)
org.apache.catalina.connector.CoyoteAdapter.service(CoyoteAdapter.java:298)
org.apache.coyote.http11.Http11Processor.process(Http11Processor.java:857)
org.apache.coyote.http11.Http11Protocol$Http11ConnectionHandler.process(Http11Protocol.java:588)
org.apache.tomcat.util.net.JIoEndpoint$Worker.run(JIoEndpoint.java:489)
java.lang.Thread.run(Thread.java:722)

note The full stack trace of the root cause is available in the Apache Tomcat/6.0.29 logs.
--------------------编程问答-------------------- java.lang.ClassNotFoundException: com.linkaibo.Httpsevlet.HelloWorldServlet
HelloWorldServlet看看这个类 --------------------编程问答-------------------- 多记几个异常名。对你有好处。 --------------------编程问答-------------------- java.lang.ClassNotFoundException: com.linkaibo.Httpsevlet.HelloWorldServlet 这个类明显有问题

补充：Java ,  Web 开发