I have the following simple example from the py4j document:
from py4j.java_gateway import JavaGateway
def main():
print("Hello")
gateway = JavaGateway() # connect to the JVM
random = gateway.jvm.java.util.Random() # create a java.util.Random instance
number1 = random.nextInt(10) # call the Random.nextInt method
number2 = random.nextInt(10)
print(number1,number2)
if __name__ == '__main__':
main()
I tried to run it, but get the following error:
Traceback (most recent call last):
File "/Users/edamameQ/github/myTest/main.py", line 16, in <module>
main()
File "/Users/edamameQ/github/myTest/main.py", line 7, in main
random = gateway.jvm.java.util.Random() # create a java.util.Random instance
File "/Library/Python/2.7/site-packages/py4j/java_gateway.py", line 1188, in __getattr__
"\n" + proto.END_COMMAND_PART)
File "/Library/Python/2.7/site-packages/py4j/java_gateway.py", line 624, in send_command
connection = self._get_connection()
File "/Library/Python/2.7/site-packages/py4j/java_gateway.py", line 579, in _get_connection
connection = self._create_connection()
File "/Library/Python/2.7/site-packages/py4j/java_gateway.py", line 585, in _create_connection
connection.start()
File "/Library/Python/2.7/site-packages/py4j/java_gateway.py", line 697, in start
raise Py4JNetworkError(msg, e)
py4j.protocol.Py4JNetworkError: An error occurred while trying to connect to the Java server
Is there anything I should do in order to connect to a Java server? Thanks!
Actually I need to start the JavaGateway separately. i.e. run the following Java application first, then the python would work.
import py4j.GatewayServer;
public class myTest {
public static void main(String[] args) {
myTest app = new myTest();
// app is now the gateway.entry_point
GatewayServer server = new GatewayServer(app);
server.start();
}
}
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