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Date: Fri, 26 Feb 2016 15:04:23 +0530
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 <CAEr=Az1Qgbh3UFe_j6pv4+9i3VOFgNARy=H3nzEa_py1ZMQciQ@mail.gmail.com>
Subject: Need some help to understand the cause of the error
From: Nirmalya Sengupta <sengupta.nirmalya@gmail.com>
To: user@flink.apache.org
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Hello Aljoscha,

I have also tried by using the field's name in the sum("field3") function
(like you have suggested), but this time the exception is different:

--------------------------------------------------------------------

Exception in thread "main" java.lang.ExceptionInInitializerError
at
org.apache.flink.quickstart.StreamWindowExperiments.MultiWindowing.main(MultiWindowing.scala)
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:497)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:140)
Caused by: java.lang.IllegalArgumentException: Key expressions are only
supported on POJO types and Tuples. A type is considered a POJO if all its
fields are public, or have both getters and setters defined
at
org.apache.flink.streaming.util.FieldAccessor$PojoFieldAccessor.<init>(FieldAccessor.java:175)
at
org.apache.flink.streaming.util.FieldAccessor.create(FieldAccessor.java:92)
at
org.apache.flink.streaming.api.functions.aggregation.SumAggregator.<init>(SumAggregator.java:49)
at
org.apache.flink.streaming.api.datastream.WindowedStream.sum(WindowedStream.java:390)
at
org.apache.flink.quickstart.StreamWindowExperiments.MultiWindowing$.<init>(MultiWindowing.scala:63)
at
org.apache.flink.quickstart.StreamWindowExperiments.MultiWindowing$.<clinit>(MultiWindowing.scala)
... 6 more

---------------------------------------------------------------------

I have used both of the styles of calling sum() in earlier, but I never got
this exception. That's why I am a little confused. 'Reading' is a _case
class_ and hence, a POJO as I understand. Yet, the message seems to say
that it is not.

--  Nirmalya

-- 
Software Technologist
http://www.linkedin.com/in/nirmalyasengupta
"If you have built castles in the air, your work need not be lost. That is
where they should be.
Now put the foundation under them."

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<div dir=3D"ltr">Hello Aljoscha,<div><br></div><div>I have also tried by us=
ing the field&#39;s name in the sum(&quot;field3&quot;) function (like you =
have suggested), but this time the exception is different:<br clear=3D"all"=
><div><br></div><div>------------------------------------------------------=
--------------</div><div><br></div><div><div><font face=3D"monospace, monos=
pace">Exception in thread &quot;main&quot; java.lang.ExceptionInInitializer=
Error</font></div><div><font face=3D"monospace, monospace"><span class=3D""=
 style=3D"white-space:pre">	</span>at org.apache.flink.quickstart.StreamWin=
dowExperiments.MultiWindowing.main(MultiWindowing.scala)</font></div><div><=
font face=3D"monospace, monospace"><span class=3D"" style=3D"white-space:pr=
e">	</span>at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)</=
font></div><div><font face=3D"monospace, monospace"><span class=3D"" style=
=3D"white-space:pre">	</span>at sun.reflect.NativeMethodAccessorImpl.invoke=
(NativeMethodAccessorImpl.java:62)</font></div><div><font face=3D"monospace=
, monospace"><span class=3D"" style=3D"white-space:pre">	</span>at sun.refl=
ect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:4=
3)</font></div><div><font face=3D"monospace, monospace"><span class=3D"" st=
yle=3D"white-space:pre">	</span>at java.lang.reflect.Method.invoke(Method.j=
ava:497)</font></div><div><font face=3D"monospace, monospace"><span class=
=3D"" style=3D"white-space:pre">	</span>at com.intellij.rt.execution.applic=
ation.AppMain.main(AppMain.java:140)</font></div><div><font face=3D"monospa=
ce, monospace">Caused by: java.lang.IllegalArgumentException: Key expressio=
ns are only supported on POJO types and Tuples. A type is considered a POJO=
 if all its fields are public, or have both getters and setters defined</fo=
nt></div><div><font face=3D"monospace, monospace"><span class=3D"" style=3D=
"white-space:pre">	</span>at org.apache.flink.streaming.util.FieldAccessor$=
PojoFieldAccessor.&lt;init&gt;(FieldAccessor.java:175)</font></div><div><fo=
nt face=3D"monospace, monospace"><span class=3D"" style=3D"white-space:pre"=
>	</span>at org.apache.flink.streaming.util.FieldAccessor.create(FieldAcces=
sor.java:92)</font></div><div><font face=3D"monospace, monospace"><span cla=
ss=3D"" style=3D"white-space:pre">	</span>at org.apache.flink.streaming.api=
.functions.aggregation.SumAggregator.&lt;init&gt;(SumAggregator.java:49)</f=
ont></div><div><font face=3D"monospace, monospace"><span class=3D"" style=
=3D"white-space:pre">	</span>at org.apache.flink.streaming.api.datastream.W=
indowedStream.sum(WindowedStream.java:390)</font></div><div><font face=3D"m=
onospace, monospace"><span class=3D"" style=3D"white-space:pre">	</span>at =
org.apache.flink.quickstart.StreamWindowExperiments.MultiWindowing$.&lt;ini=
t&gt;(MultiWindowing.scala:63)</font></div><div><font face=3D"monospace, mo=
nospace"><span class=3D"" style=3D"white-space:pre">	</span>at org.apache.f=
link.quickstart.StreamWindowExperiments.MultiWindowing$.&lt;clinit&gt;(Mult=
iWindowing.scala)</font></div><div><font face=3D"monospace, monospace"><spa=
n class=3D"" style=3D"white-space:pre">	</span>... 6 more</font></div></div=
><div><br></div><div>------------------------------------------------------=
---------------</div><div><br></div><div>I have used both of the styles of =
calling sum() in earlier, but I never got this exception. That&#39;s why I =
am a little confused. &#39;Reading&#39; is a _case class_ and hence, a POJO=
 as I understand. Yet, the message seems to say that it is not.</div><div><=
br></div><div>-- =C2=A0Nirmalya</div><div><br></div>-- <br><div class=3D"gm=
ail_signature">Software Technologist<br><a href=3D"http://www.linkedin.com/=
in/nirmalyasengupta" target=3D"_blank">http://www.linkedin.com/in/nirmalyas=
engupta</a><br>&quot;If you have built castles in the air, your work need n=
ot be lost. That is where they should be.<br>Now put the foundation under t=
hem.&quot;</div>
</div></div>

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