[Py4j-users] Calling python from java : py4j.Py4JException: An exception was raised by the Python Proxy. Return Message: x

[sudheera N. <sud...@gm...>]

Hi

 I am trying to use py4j to call python method from java. I was successful
in calling java methods from python. But I need to initiate the call from
java side as java is my main program and I want to interface a power system
simulation software called PowerFactory  to java via python, (python
provide nice interface to handle the PowerFactory ) .

      So, When I try to call the python from java I get following error.


ERROR:py4j.java_gateway:Unknown command runPowerFactory
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
  File
"C:\Python33\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py",
line 685, in runfile
    execfile(filename, namespace)
  File
"C:\Python33\lib\site-packages\spyderlib\widgets\externalshell\sitecustomize.py",
line 85, in execfile
    exec(compile(open(filename, 'rb').read(), filename, 'exec'), namespace)
  File "C:/Program Files (x86)/DIgSILENT/PowerFactory
15.1/python/PhdTheses_extClass.py", line 44, in <module>
    abc = toFromjava_ex.CollectDemandData(toFromjava1)
  File "C:\Python33\lib\site-packages\py4j\java_gateway.py", line 813, in
__call__
    answer, self.gateway_client, self.target_id, self.name)
  File "C:\Python33\lib\site-packages\py4j\protocol.py", line 308, in
get_return_value
    format(target_id, ".", name), value)
py4j.protocol.Py4JJavaError: An error occurred while calling
o7.CollectDemandData.
: py4j.Py4JException: An exception was raised by the Python Proxy. Return
Message: x

    at py4j.Protocol.getReturnValue(Protocol.java:434)

    at
py4j.reflection.PythonProxyHandler.invoke(PythonProxyHandler.java:113)

    at com.sun.proxy.$Proxy0.runPowerFactory(Unknown Source)

    at repastextrun.JavaPyCall.CollectDemandData(JavaPyCall.java:10)

    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)

    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)

    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)

    at java.lang.reflect.Method.invoke(Unknown Source)

    at py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:231)

    at py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:381)

    at py4j.Gateway.invoke(Gateway.java:259)

    at py4j.commands.AbstractCommand.invokeMethod(AbstractCommand.java:133)

    at py4j.commands.CallCommand.execute(CallCommand.java:79)

    at py4j.GatewayConnection.run(GatewayConnection.java:209)

    at java.lang.Thread.run(Unknown Source)





+++++++++++++++++++++++++++++++++++++++++++++++++++
My java Interface looks like

package repastextrun;

public interface javaPyCallInt {

    public void runPowerFactory();


}

+++++++++++++++++++++++++++++++++++++++++++++++++

And the java class that I'm calling python looks like

package repastextrun;
import java.io.IOException;

import py4j.GatewayServer;

public class JavaPyCall {

    public void CollectDemandData(javaPyCallInt javaInt) throws IOException{

        javaInt.runPowerFactory();
        System.out.println(javaInt);
    }

    public static void main(String[] args) {
        GatewayServer server = new GatewayServer(new JavaPyCall());
        server.start();
    }



}




-- 
Sudheera Navaratne