Re: [Py4j-users] How to run Stack example in the docs?

[Barthelemy D. <bar...@in...>]

Hi,

thanks for using Py4J!

I believe the problem might be the package. If you copied/pasted the
code exactly, the Java source files need to be in the appropriate
directories (e.g., py4j/examples/StackEntryPoint). After compiling the
classes, you need to specify the fully qualified name of the main
class when invoking java:

java -cp .:$JARFILE py4j.examples.StackEntryPoint

I suggest though that you just remove the "package py4j.examples;"
line in both files. You should then be able to compile and run the
example code.

Alternatively, you can use the StackEntryPoint class that is provided by py4j:
java -cp $JARFILE py4j.examples.StackEntryPoint

HTH,
Barthelemy

On Mon, Dec 8, 2014 at 11:39 AM, listserve <tom...@gm...> wrote:
> Hello,
>
> I'm trying to run the code in the docs from here:
>
> http://py4j.sourceforge.net/getting_started.html#writing-the-java-program
>
> I'm not that experienced with Java so I may very well be making a
> mistake unrelated to py4j, but I'm unable to run the code regardless.
> This is what I've done: I saved the Stack code in a file called
> Stack.java and the other code in StackEntryPoint.java. I compiled it at
> the command line with the following:
>
> JARFILE=/usr/local/share/py4j/py4j0.8.2.1.jar
> javac -cp $JARFILE *.java
>
> That gave no error. I then tried to run it with:
>
> java -cp $JARFILE:. StackEntryPoint
>
> and I get the following error:
>
> Exception in thread "main" java.lang.NoClassDefFoundError:
> StackEntryPoint (wrong name: py4j/examples/StackEntryPoint)
>         at java.lang.ClassLoader.defineClass1(Native Method)
>         at java.lang.ClassLoader.defineClass(ClassLoader.java:800)
>         at java.security.SecureClassLoader.defineClass(SecureClassLoader.java:142)
>         at java.net.URLClassLoader.defineClass(URLClassLoader.java:449)
>         at java.net.URLClassLoader.access$100(URLClassLoader.java:71)
>         at java.net.URLClassLoader$1.run(URLClassLoader.java:361)
>         at java.net.URLClassLoader$1.run(URLClassLoader.java:355)
>         at java.security.AccessController.doPrivileged(Native Method)
>         at java.net.URLClassLoader.findClass(URLClassLoader.java:354)
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:425)
>         at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:308)
>         at java.lang.ClassLoader.loadClass(ClassLoader.java:358)
>         at sun.launcher.LauncherHelper.checkAndLoadMain(LauncherHelper.java:482)
>
> I am running Linux Mint 17 (which is basically Ubuntu) and the following
> is my versions of java/javac:
>
> $ java -version
> java version "1.7.0_65"
> OpenJDK Runtime Environment (IcedTea 2.5.3) (7u71-2.5.3-0ubuntu0.14.04.1)
> OpenJDK 64-Bit Server VM (build 24.65-b04, mixed mode)
>
> $ javac -version
> javac 1.7.0_65
>
> Thanks for any help.
>
> Cheers,
> Thomas
>
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