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How to Call Python Code from Java and Vice Versa

Integrating Java and Python: How to Call Python Code from Java and Vice Versa

In today’s technology landscape, combining the strengths of multiple programming languages can lead to powerful and flexible solutions. One such combination is integrating Java and Python, two popular languages with their own unique capabilities.


To follow along with this example, you’ll need the following:

  1. Java Development Kit (JDK) installed on your device.
  2. Python is installed on your device.
  3. A Java IDE, such as Eclipse or IntelliJ IDEA, and a Python IDE, such as PyCharm or Jupyter Notebook.

Example Scenario:

Let’s consider a scenario where we have a Java application that performs complex mathematical calculations, and we want to leverage a Python library called “numpy” to handle the mathematical computations efficiently.

Step 1: Setting up the Java Project

1. Create a new Java project in your preferred IDE.
2. Configure the project to include the necessary dependencies to call Python code. You can use the “jython” library or the “javax.script” package for this purpose.

Step 2: Writing the Java Code

1. Import the required Java classes and packages.
2. Initialize the Python interpreter in your Java code using the appropriate methods.
3. Call the Python code and retrieve the results in Java variables.
4. Perform any necessary post-processing or further operations on the retrieved data using Java.

Step 3: Writing the Python Code

1. Install the required Python library (“numpy” in our example) using pip or any package manager you choose.
2. Write the necessary Python code to perform the mathematical calculations using the “numpy” library.
3. Save the Python code in a separate file, ensuring it is accessible to the Java project.

Step 4: Executing the Integration

1. Compile and run the Java code. Ensure that the Python code file is correctly referenced in the Java project.
2. Observe the integration in action as the Java application calls the Python code and receives the computed results.

Real-Time Example:

Let’s consider a Java application that requires matrix multiplication. We can leverage the “numpy” library’s efficient matrix multiplication capabilities in Python.

Java Code (

Python Code (


Integrating Java and Python allows us to harness the capabilities of both languages, enabling powerful and flexible solutions. In this blog post, we explored how to call Python code from Java and vice versa using a real-time example of matrix multiplication. By leveraging the strengths of each language, we can create applications that combine the efficiency of Python libraries with the robustness and scalability of Java.

Remember to adjust the integration steps according to your specific requirements and dependencies. With a solid understanding of the integration process, you can explore various use cases and expand the capabilities of your applications by seamlessly combining Java and Python.

Happy coding!


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