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This was reported by Igor:

-------- Forwarded Message --------
Subject: Issue with COMBO-BOX
Date: Thu, 11 Feb 2016 07:25:32 -0500
From: Igor ...
To: Greg ...

Greg,

I've noticed the following issue. If I started the converted mouse.p (attached) and the first mouse action after startup is any COMBO-BOX activation the following exception happens:

Feb 11, 2016 7:19:29 AM Dispatcher.processInbound()
SEVERE: {main} Unexpected throwable.
java.lang.reflect.InvocationTargetException
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.goldencode.p2j.util.MethodInvoker.invoke(MethodInvoker.java:76)
at com.goldencode.p2j.net.Dispatcher.processInbound(Dispatcher.java:705)
at com.goldencode.p2j.net.Conversation.block(Conversation.java:319)
at com.goldencode.p2j.net.Conversation.waitMessage(Conversation.java:257)
at com.goldencode.p2j.net.Queue.transactImpl(Queue.java:1128)
at com.goldencode.p2j.net.Queue.transact(Queue.java:585)
at com.goldencode.p2j.net.BaseSession.transact(BaseSession.java:223)
at com.goldencode.p2j.net.HighLevelObject.transact(HighLevelObject.java:163)
at com.goldencode.p2j.net.RemoteObject$RemoteAccess.invokeCore(RemoteObject.java:1425)
at com.goldencode.p2j.net.InvocationStub.invoke(InvocationStub.java:97)
at com.sun.proxy.$Proxy4.standardEntry(Unknown Source)
at com.goldencode.p2j.main.ClientCore.start(ClientCore.java:281)
at com.goldencode.p2j.main.ClientCore.start(ClientCore.java:102)
at com.goldencode.p2j.main.ClientDriver.start(ClientDriver.java:201)
at com.goldencode.p2j.main.CommonDriver.process(CommonDriver.java:398)
at com.goldencode.p2j.main.ClientDriver.process(ClientDriver.java:95)
at com.goldencode.p2j.main.ClientDriver.main(ClientDriver.java:267)
Caused by: java.lang.NullPointerException
at com.goldencode.p2j.ui.chui.ThinClient.waitForWorker(ThinClient.java:11105)
at com.goldencode.p2j.ui.client.ComboBox.activate(ComboBox.java:1113)
at com.goldencode.p2j.ui.client.gui.ComboBoxGuiImpl.access$700(ComboBoxGuiImpl.java:84)
at com.goldencode.p2j.ui.client.gui.ComboBoxGuiImpl$4.run(ComboBoxGuiImpl.java:440)
at com.goldencode.p2j.ui.chui.ThinClient.waitForEvent(ThinClient.java:13006)
at com.goldencode.p2j.ui.chui.ThinClient.waitForWorker(ThinClient.java:10963)
at com.goldencode.p2j.ui.chui.ThinClient.waitFor(ThinClient.java:10537)
at com.goldencode.p2j.ui.chui.ThinClient.waitFor(ThinClient.java:10491)
... 21 more

If I e.g. first click at any(?) other widget everything is OK. The preliminary analysis reveals that the registry fails to find DropDown.

This can be of course a result of my changes but it is not likely.

Should I continue investigation?

Thank you,
Igor.

Please find the diff file attached. The fix is committed to the task branch 2565a

Code Review Task Branch 2565a Revisions 11019/11020

Overall, the approach seems good.

1. Why are WidgetRegistry.getComponents() and WidgetRegistry.removeWidget() synchronized when all access to widgetList is already protected by the ReentrantReadWriteLock?

2. The import com.codahale.metrics.*; should be removed.

3. Please remove the commented logging in WidgetRegistry.getComponent().

4. In the future, please note the revision that contains the change, so the reviewer doesn't have to search for it.

5. The best way to post diffs is as a text file. Capture the diffs like this:

bzr diff -r11018..11020 src/com/goldencode/p2j/ui/client/WidgetRegistry.java > wr.txt

Then attach the wr.txt to the entry (as I have done in this task history entry). By doing it this way, the viewer can see the diff in the browser. The way you did it, I had to download the diff AND it didn't even have the target filename (WidgetRegistry) in it, so the reader might now know where the diffs come from.

Resolved by trunk revision 10976 (merged from 2565a).