I'm working with WAS 7.0 and I found this error:
[27/10/13 11:55:06:727 CET] 00000023 servlet E com.ibm.ws.webcontainer.servlet.ServletWrapper run [Servlet Error]-[class java.lang.NullPointerException: null]: java.lang.ClassNotFoundException: class java.lang.NullPointerException: null
at java.beans.Beans.instantiate(Beans.java:190)
at java.beans.Beans.instantiate(Beans.java:75)
at com.ibm.ws.webcontainer.servlet.ServletWrapper$1.run(ServletWrapper.java:1909)
at com.ibm.ws.security.util.AccessController.doPrivileged(AccessController.java:118)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.loadServlet(ServletWrapper.java:1900)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:730)
at com.ibm.ws.webcontainer.servlet.ServletWrapper.handleRequest(ServletWrapper.java:502)
at com.ibm.ws.webcontainer.servlet.ServletWrapperImpl.handleRequest(ServletWrapperImpl.java:179)
at com.ibm.ws.webcontainer.webapp.WebApp.handleRequest(WebApp.java:3933)
at com.ibm.ws.webcontainer.webapp.WebGroup.handleRequest(WebGroup.java:276)
at com.ibm.ws.webcontainer.WebContainer.handleRequest(WebContainer.java:931)
at com.ibm.ws.webcontainer.WSWebContainer.handleRequest(WSWebContainer.java:1583)
at com.ibm.ws.webcontainer.channel.WCChannelLink.ready(WCChannelLink.java:186)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleDiscrimination(HttpInboundLink.java:452)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.handleNewRequest(HttpInboundLink.java:511)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.processRequest(HttpInboundLink.java:305)
at com.ibm.ws.http.channel.inbound.impl.HttpInboundLink.ready(HttpInboundLink.java:276)
at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.sendToDiscriminators(NewConnectionInitialReadCallback.java:214)
at com.ibm.ws.tcp.channel.impl.NewConnectionInitialReadCallback.complete(NewConnectionInitialReadCallback.java:113)
at com.ibm.ws.tcp.channel.impl.AioReadCompletionListener.futureCompleted(AioReadCompletionListener.java:165)
at com.ibm.io.async.AbstractAsyncFuture.invokeCallback(AbstractAsyncFuture.java:217)
at com.ibm.io.async.AsyncChannelFuture.fireCompletionActions(AsyncChannelFuture.java:161)
at com.ibm.io.async.AsyncFuture.completed(AsyncFuture.java:138)
at com.ibm.io.async.ResultHandler.complete(ResultHandler.java:204)
at com.ibm.io.async.ResultHandler.runEventProcessingLoop(ResultHandler.java:775)
at com.ibm.io.async.ResultHandler$2.run(ResultHandler.java:905)
at com.ibm.ws.util.ThreadPool$Worker.run(ThreadPool.java:1604)
The thing is that it doesn't show up all the time but only with the servlets I've created recently (i.e. old servlets are working, but new ones throw this error). For this reason I've checked that everything is properly compiled and linked and I haven't seen anything different from the working servlets.
Any hints on how to further debug this issue or how to solve it are really appreciated.
Thanks in advance, Río
The version of Java 6 included in WebSphere Application Server has the lost the fix for Java bug 4256569, which obscures the actual cause of the failure. If this issue is important to you, I recommend opening a PMR with IBM. I verified that this issue has been resolved in the Java 7 included in WebSphere Application Server 8 and later.
I found the problem. Despite what it looks like, it is not a platform problem, I just forgot to initialize an ArrayList and hell broke loose. Hooray for such useful compiler '¬¬
来源：https://stackoverflow.com/questions/19617359/odd-behavior-in-was-7-0-java-lang-classnotfoundexception-class-java-lang-nullp