Monday, March 6, 2017

Weird issue: java.nio.charset.IllegalCharsetNameException: UTF-8

I recently met a weird issue, thought I’d noted down for future references.

When I tried to ant build, this error happened:

Error occurred during initialization of VM
java.nio.charset.IllegalCharsetNameException: UTF-8
        at java.nio.charset.Charset.checkName(
        at java.nio.charset.Charset.lookup2(
        at java.nio.charset.Charset.lookup(
        at java.nio.charset.Charset.defaultCharset(
        at sun.nio.cs.StreamEncoder.forOutputStreamWriter(
        at java.lang.System.newPrintStream(
       at java.lang.System.initializeSystemClass(

This is easy, a few googled showed this error has something to do with how you pass encoding to the java runtime argument. ant --help shows ant has an argument execdebug, which will show the execution command, so:

vagrant@exp:/PPM941/SourceCode/java$ ant --execdebug

 -classpath "/usr/share/ant/lib/ant-launcher.jar" -Dant.home="/usr/share/ant" -Dant.library.dir="/usr/share/ant/lib"

Now here comes the weird part, the red part is supposed to be the java execution command, but it can’t be! A normal java execution command should start with “java”, and followed with a bunch of arguments, what is this red part?

The insight comes slowly, after a long time tinkering (with lots of debugging on the /usr/bin/ant file), I began to suspect, could Linux mess up with the string concatenation? Google “strange string concatenation linux) does show a lot of results.

To prove this, I used sed –n l, sed l shows the unprintable characters; sed –n suppresses automatic printing (so the red part in the previous paragraph doesn’t show):

$ ant --execdebug | sed -n l

exec "/usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java" -Xmx520m -Dfil\
e.encoding=UTF-8\r -classpath "/usr/share/ant/lib/ant-launcher.jar" -\
Dant.home="/usr/share/ant" -Dant.library.dir="/usr/share/ant/lib" org\

In the output, you can clearly see that UTF-8 has a \r carriage return.

Weirder! How did it get in? Eventually, I noticed that I accidently executed a file with windows end-of-line in linux. This file will export some environmental variables, one of them is ANT_OPTS="-Xmx520m -Dfile.encoding=UTF-8". Linux shell executed this file even though it has windows end-of-line (though it did throw out some warnings, which slipped my attention).

The issue is strange because its symptom has nothing to do with the true nature of the issue.

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