Questions tagged [py4j]

Py4J enables Python programs running in a Python interpreter to dynamically access Java objects in a Java Virtual Machine. Methods are called as if the Java objects resided in the Python interpreter and Java collections can be accessed through standard Python collection methods. Py4J also enables Java programs to call back Python objects. Py4J is distributed under the BSD license.

Here is a brief example of what you can do with Py4J. The following Python program creates a java.util.Random instance from a JVM and calls some of its methods. It also accesses a custom Java class, AdditionApplication to add the generated numbers.

 from py4j.java_gateway import JavaGateway

 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)

(2, 7)

 addition_app = gateway.entry_point        # get the AdditionApplication instance

 addition_app.addition(number1,number2)    # call the addition method

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