Re: [jgroups-dev] What does cause NullPointerException?

You didn't send the whole code, so I wasn't able to investigate. I 
suggest debug this yourself by setting a breakpoint in your code... this 
is probably the fastest way to find the cause

On 25/12/15 13:03, Development issues wrote:
> The exception occurs in your code (Zab2PhasesTest.resetProtocol), so
> without that code I don't know what's going on. If you post a unit test
> and package up the code I could take a look. Or you set a breakpoint in
> Zab2PhasesTest.resetProtocol() and see what's null that triggers the NPE.
>
> Yes, The exception occurs in your code (Zab2PhasesTest.resetProtocol) in
> line channel.send(msg).
> In fact, I do not use Junit test, when I am coding and  testing the
> code, I just compile and run it in Linux machines using command line.
> The attachment shows the codes. They are two files, one called
> Zab2PhasesTest and second called Zab2PhasesClient. Zab2PhasesClient uses
> by Zab2PhasesTest to initial senders to send requests to servers.
>
> Note that NPE occurs in Zab2PhasesTest.resetProtocol in line
> channel.send(msg, line 192.
>
> Thank you indeed
>
> Ibrahim
>
>
>
> On Friday, December 25, 2015 7:58 AM, JGroups - Dev mailing list [via
> JGroups] <[hidden email] </user/SendEmail.jtp?type=node&node=10927&i=0>>
> wrote:
>
>
> The exception occurs in your code (Zab2PhasesTest.resetProtocol), so
> without that code I don't know what's going on. If you post a unit test
> and package up the code I could take a look. Or you set a breakpoint in
> Zab2PhasesTest.resetProtocol() and see what's null that triggers the NPE.
>
> On 24/12/15 22:34, Development issues wrote:
>
>  > <<An NPE can only occur if channel is null at this point...
>  > <<JChannel.getAddress() can of course return null if the channel hasn't
>  > <<been connected yet, but you'd only get an NPE if you try to reference
>  > <<local_address
>  > The channel is connected and I use it without any problem before the
>  > line where the exception occur. Meaning that with the same code I manage
>  > to use channel to send requests to the servers, but where the execution
>  > come to line channel.send(msg), the exception occurs. This is why I am
>  > surprised when I use channel first time it worked but when I use it
>  > again I have NullPointerException.
>  > <<OK. Can you also subscribe properly? So far, I've had to approve
> all of
>  > <<your posts individually...
>  > I thought I am already subscribe by using and logging in to this site
>  > http://jgroups.1086181.n5.nabble.com/.
>  > No worry, I have found another site and just subscribe today which is
>  > https://sourceforge.net/p/javagroups/mailman/javagroups-development/. I
>  > hope now I am subscribed correctly.
>  > The following is stack trace as requested:
>  > java.lang.NullPointerException
>  > at
>  >
> org.jgroups.protocols.jz.Zab2PhasesTest.resetProtocol(Zab2PhasesTest.java:192)
>
>  > at
>  >
> org.jgroups.protocols.jz.Zab2PhasesTest.finishedSend(Zab2PhasesTest.java:318)
>
>  > at
>  >
> org.jgroups.protocols.jz.Zab2PhasesClient.receive(Zab2PhasesClient.java:143)
>
>  > at org.jgroups.JChannel.invokeCallback(JChannel.java:812)
>  > at org.jgroups.JChannel.up(JChannel.java:736)
>  > at org.jgroups.stack.ProtocolStack.up(ProtocolStack.java:1029)
>  > at
> org.jgroups.protocols.pbcast.STATE_TRANSFER.up(STATE_TRANSFER.java:146)
>  > at org.jgroups.protocols.FRAG2.up(FRAG2.java:165)
>  > at
>  >
> org.jgroups.protocols.jz.Zab2Phases.handleOrderingResponse(Zab2Phases.java:588)
>
>  > at org.jgroups.protocols.jz.Zab2Phases.up(Zab2Phases.java:256)
>  > at org.jgroups.protocols.jz.Zab2Phases.up(Zab2Phases.java:277)
>  > at org.jgroups.protocols.RSVP.up(RSVP.java:237)
>  > at org.jgroups.stack.Protocol.up(Protocol.java:420)
>  > at org.jgroups.protocols.pbcast.STABLE.up(STABLE.java:294)
>  > at org.jgroups.protocols.UNICAST3.deliverBatch(UNICAST3.java:1087)
>  > at org.jgroups.protocols.UNICAST3.removeAndDeliver(UNICAST3.java:886)
>  > at org.jgroups.protocols.UNICAST3.handleDataReceived(UNICAST3.java:790)
>  > at org.jgroups.protocols.UNICAST3.up(UNICAST3.java:426)
>  > at org.jgroups.protocols.pbcast.NAKACK2.up(NAKACK2.java:619)
>  > at org.jgroups.protocols.BARRIER.up(BARRIER.java:152)
>  > at org.jgroups.protocols.VERIFY_SUSPECT.up(VERIFY_SUSPECT.java:155)
>  > at org.jgroups.protocols.FD_ALL.up(FD_ALL.java:200)
>  > at org.jgroups.protocols.FD_SOCK.up(FD_SOCK.java:297)
>  > at org.jgroups.protocols.MERGE2.up(MERGE2.java:237)
>  > at org.jgroups.protocols.Discovery.up(Discovery.java:277)
>  > at org.jgroups.protocols.TP.passMessageUp(TP.java:1572)
>  > at org.jgroups.protocols.TP$MyHandler.run(TP.java:1791)
>  > at
>  >
> java.util.concurrent.ThreadPoolExecutor.runWorker(ThreadPoolExecutor.java:1142)
>
>  > at
>  >
> java.util.concurrent.ThreadPoolExecutor$Worker.run(ThreadPoolExecutor.java:617)
>


-- 
Bela Ban, JGroups lead (http://www.jgroups.org)


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