# Exception in thread "main" java.lang.ClassNotFoundException: rational.namespace **URL:** \ **Category:** Uncategorized\ **Created:** [November 5, 2012, 5:04pm UTC](https://discuss.kotlinlang.org/t/exception-in-thread-main-java-lang-classnotfoundexception-rational-namespace/1042 "2012-11-05T17:04:30Z")\ **Posts on this page:** 5\ **Page:** 1
**Author:** ![ianclarke](https://avatars.discourse-cdn.com/v4/letter/i/7bcc69/32.png) [@ianclarke](https://discuss.kotlinlang.org/u/ianclarke)\ **Post date:** [November 5, 2012, 5:04pm UTC](https://discuss.kotlinlang.org/t/exception-in-thread-main-java-lang-classnotfoundexception-rational-namespace/1042/1 "2012-11-05T17:04:30Z")
So I've contined to work on my Rational number class, but now I'm encountering a problem - I can't seem to run the main function in the Rational.kt class.  The currenct source is available here: [https://github.com/sanity/kotlin-rational](https://github.com/sanity/kotlin-rational) When I try to run it I get the following error: /Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/bin/java -Didea.launcher.port=7534 “-Didea.launcher.bin.path=/Users/ian/Applications/IntelliJ IDEA 12 EAP.app/bin” -Dfile.encoding=UTF-8 -classpath “/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/lib/ant-javafx.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/lib/dt.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/lib/javafx-doclet.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/lib/javafx-mx.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/lib/jconsole.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/lib/sa-jdi.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/lib/tools.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/jre/lib/charsets.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/jre/lib/jce.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/jre/lib/jfr.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/jre/lib/jfxrt.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/jre/lib/JObjC.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/jre/lib/jsse.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/jre/lib/management-agent.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/jre/lib/resources.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/jre/lib/rt.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/jre/lib/ext/dnsns.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/jre/lib/ext/localedata.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/jre/lib/ext/sunec.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/jre/lib/ext/sunjce\_provider.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/jre/lib/ext/sunpkcs11.jar:/Library/Java/JavaVirtualMachines/1.7.0.jdk/Contents/Home/jre/lib/ext/zipfs.jar:/Users/ian/workspace/RationalNumber/target/classes:/Users/ian/.m2/repository/com/google/guava/guava/r09/guava-r09.jar:/Users/ian/.m2/repository/org/jetbrains/kotlin/kotlin-stdlib/0.1.3395/kotlin-stdlib-0.1.3395.jar:/Users/ian/.m2/repository/org/jetbrains/kotlin/kotlin-runtime/0.1.3395/kotlin-runtime-0.1.3395.jar:/Users/ian/Applications/IntelliJ IDEA 12 EAP.app/lib/idea\_rt.jar” com.intellij.rt.execution.application.AppMain rational.namespace Exception in thread “main” java.lang.ClassNotFoundException: rational.namespace at java.net.URLClassLoader$1.run(URLClassLoader.java:366) at java.net.URLClassLoader$1.run(URLClassLoader.java:355) at java.security.AccessController.doPrivileged(Native Method) at java.net.URLClassLoader.findClass(URLClassLoader.java:354) at java.lang.ClassLoader.loadClass(ClassLoader.java:423) at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308) at java.lang.ClassLoader.loadClass(ClassLoader.java:356) at java.lang.Class.forName0(Native Method) at java.lang.Class.forName(Class.java:186) at com.intellij.rt.execution.application.AppMain.main(AppMain.java:113) Compilation appears successful: 10:05:14 AM Compilation completed successfully in 1 sec 10:05:40 AM All files are up-to-date However, when I look in RationalNumber/target/classes the directory is empty, where are the compiled files going? I’ve tried moving the Rational file around into another package, nothing seems to persuade it to run.  It does appear to be building fine though.  Any ideas? ---
**Author:** ![abreslav](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.kotlinlang.org/abreslav/32/8279_2.png) [@abreslav](https://discuss.kotlinlang.org/u/abreslav)\ **Post date:** [November 5, 2012, 5:09pm UTC](https://discuss.kotlinlang.org/t/exception-in-thread-main-java-lang-classnotfoundexception-rational-namespace/1042/2 "2012-11-05T17:09:25Z")
What version of IntelliJ IDEA are you running? ---
**Author:** ![abreslav](https://sea1.discourse-cdn.com/flex019/user_avatar/discuss.kotlinlang.org/abreslav/32/8279_2.png) [@abreslav](https://discuss.kotlinlang.org/u/abreslav)\ **Post date:** [November 5, 2012, 5:24pm UTC](https://discuss.kotlinlang.org/t/exception-in-thread-main-java-lang-classnotfoundexception-rational-namespace/1042/3 "2012-11-05T17:24:59Z")
Go to Settings/Compiler and uncheck the "Use external build" checkbox. ---
**Author:** ![Flow](https://avatars.discourse-cdn.com/v4/letter/f/8edcca/32.png) [@Flow](https://discuss.kotlinlang.org/u/Flow)\ **Post date:** [November 5, 2012, 6:30pm UTC](https://discuss.kotlinlang.org/t/exception-in-thread-main-java-lang-classnotfoundexception-rational-namespace/1042/4 "2012-11-05T18:30:21Z")
Forget my previous message here. I updated Leda and the kotlin plugin and then unchecked what Andrey mentioned and now it works.:) ---
**Author:** ![ianclarke](https://avatars.discourse-cdn.com/v4/letter/i/7bcc69/32.png) [@ianclarke](https://discuss.kotlinlang.org/u/ianclarke)\ **Post date:** [November 5, 2012, 7:21pm UTC](https://discuss.kotlinlang.org/t/exception-in-thread-main-java-lang-classnotfoundexception-rational-namespace/1042/5 "2012-11-05T19:21:15Z")
That seems to have solved the problem.  FYI I'm using build IU-122.694.