[Py4j-users] Exception when printing a returned List<String> object

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Hi,


The method in my gateway server will return a List<String> object. When I access it in my python client code, the server has exception and then closed. The following is part of the exceptions




▒Q▒G▒▒ 23, 2014 5:18:14 ▒U▒▒ py4j.reflection.MethodInvoker invoke
ĵ▒i: Exception occurred in client code.
java.lang.reflect.InvocationTargetException
        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:483)
        at py4j.reflection.MethodInvoker.invoke(MethodInvoker.java:231)
        at py4j.reflection.ReflectionEngine.invoke(ReflectionEngine.java:379)
        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:207)
        at java.lang.Thread.run(Thread.java:745)
Caused by: java.util.NoSuchElementException
        at java.util.AbstractList$Itr.next(AbstractList.java:364)
        ... 11 more

What I do in client code is the following:

>>>ret = gateway.entry_point.getMyStringList(inputStr)    # it's ok to run this line
>>>print ret       # when running to this line, the server raised exception


Below is the method in server side:

public List<String> getMyStringList(String input) throws IOException {
    List<String> strList = new ArrayList<String>();
    strList = segmenter.segmentString(input);    //  this is some 3rd party API for string tokenization and has been tested OK in console, the return object is List<String>

    ​return strList;
}

It's OK to access "ret" using indices and len(), but when I just type "ret" or "print ret", then it would display the content of "ret", but then the server poped Exception and stopped. What would be the problemt? Thanks for any help!



Frank Yang



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