Hiring guide for JPython Engineers

JPython Developer Hiring Guide

JPython, now known as Jython, is a Java implementation of the Python programming language. It was initially created by Jim Hugunin in 1997 and later developed by the Jython community. The software allows Python programs to seamlessly integrate with Java libraries and compiles to Java bytecode which can run directly on a JVM (Java Virtual Machine). This unique feature enables developers to concurrently use both languages within a single project. Information sourced from "The Definitive Guide to Jython" by Josh Juneau et al., Apress publications.

Ask the right questions secure the right JPython talent among an increasingly shrinking pool of talent.

First 20 minutes

General JPython app knowledge and experience

The first 20 minutes of the interview should seek to understand the candidate's general background in JPython application development, including their experience with various programming languages, databases, and their approach to designing scalable and maintainable systems.

How would you install Jython on your machine?
You can install Jython by downloading the latest Jython installer from the official website, running the installer, and following the prompts. It's important to set the Jython path in your system environment variables for easy access.
What are some key features of Jython?
Jython has several key features like seamless integration with Java, ability to compile to Java byte code, support for Java threads and exception model, and dynamic compilation to Java byte code.
How would you import and use a Java class in Jython?
You can import a Java class in Jython using the import statement just like in Python. For example, 'from java.util import ArrayList'. You can then use the class as 'list = ArrayList()'.
What are the differences between Jython and Java?
Jython is a Python interpreter implemented in Java. It allows Python code to be run on the JVM. Java is a general-purpose programming language. Jython has dynamic typing while Java has static typing. Jython supports multiple inheritance while Java does not.
Describe the difference between Jython and CPython.
Jython and CPython are both implementations of the Python language, but Jython is written in Java and runs on the JVM, while CPython is the original implementation written in C. Jython can seamlessly import and use Java classes, while CPython cannot.
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What you’re looking for early on

Does the candidate demonstrate a strong understanding of JPython?
Has the candidate worked on relevant projects or tasks?
Can the candidate solve problems effectively?
Is the candidate familiar with the latest trends and technologies in JPython?

Next 20 minutes

Specific JPython development questions

The next 20 minutes of the interview should focus on the candidate's expertise with specific backend frameworks, their understanding of RESTful APIs, and their experience in handling data storage and retrieval efficiently.

How would you handle exceptions in Jython?
Exception handling in Jython is done similarly to Python, using try-except blocks. You can catch Java exceptions in Jython as well. For example, 'try: risky_operation() except JavaException: handle_exception()'.
What are the benefits of using Jython over Java for certain tasks?
Jython can be more expressive and concise than Java for certain tasks. It also allows for easy scripting and quick prototyping. Moreover, Jython can seamlessly use Java libraries, which can be a big advantage if you're working in a Java ecosystem.
How would you create a Jython script that uses a Java library?
First, you would import the Java library using the import statement. Then, you can use the classes and methods from the library in your Jython script. For example, 'from java.util import HashMap; map = HashMap()'.
What are some disadvantages of using Jython?
Some disadvantages of Jython include slower execution speed compared to Java, lack of some Python libraries, especially those that rely on CPython extensions, and less community support and fewer resources compared to languages like Java and Python.
Describe the difference between Jython and IronPython.
Jython and IronPython are both implementations of Python, but Jython is written in Java and runs on the JVM, while IronPython is written in C# and runs on the .NET framework. Jython can use Java libraries, while IronPython can use .NET libraries.
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The ideal back-end app developer

What you’re looking to see on the JPython engineer at this point.

At this point, a skilled JPython engineer should demonstrate strong problem-solving abilities, proficiency in JPython programming language, and knowledge of software development methodologies. Red flags include lack of hands-on experience, inability to articulate complex concepts, or unfamiliarity with standard coding practices.

Digging deeper

Code questions

These will help you see the candidate's real-world development capabilities with JPython.

What does the following JPython code do?
import sys
This code prints the version of the Python interpreter that's currently being used.
What will be the output of the following JPython code?
x = 10
y = 2
print(x // y)
The output will be 5. The '//' operator performs integer (floor) division on the operands.
What does the following JPython code do?
my_list = [1, 2, 3, 4, 5]
This code reverses the order of elements in 'my_list' and then prints the reversed list.
What does the following JPython code do?
import threading

def print_numbers():
    for i in range(10):

def print_letters():
    for letter in 'abcdefghij':

thread1 = threading.Thread(target=print_numbers)
thread2 = threading.Thread(target=print_letters)

This code creates two separate threads. One thread prints numbers from 0 to 9, and the other thread prints letters from 'a' to 'j'. The threads run concurrently.

Wrap-up questions

Final candidate for JPython Developer role questions

The final few questions should evaluate the candidate's teamwork, communication, and problem-solving skills. Additionally, assess their knowledge of microservices architecture, serverless computing, and how they handle JPython application deployments. Inquire about their experience in handling system failures and their approach to debugging and troubleshooting.

How would you compile a Jython script to Java bytecode?
You can compile a Jython script to Java bytecode using the jythonc command. For example, 'jythonc myscript.py'. This will create a .class file that can be run on the JVM.
What are the differences between Jython 2.7 and Jython 3.x?
Jython 2.7 is compatible with Python 2.7 and Jython 3.x is compatible with Python 3.x. This means that Jython 3.x includes features like the print function, unicode strings, and new syntax like the 'nonlocal' keyword, which are not available in Jython 2.7.
How would you debug a Jython script?
You can debug a Jython script using a Python debugger like pdb, or a Java debugger like jdb. You can also use an IDE that supports Jython debugging, like PyCharm or Eclipse with PyDev.

JPython application related

Product Perfect's JPython development capabilities

Beyond hiring for your JPython engineering team, you may be in the market for additional help. Product Perfect provides seasoned expertise in JPython projects, and can engage in multiple capacities.