Call java program from python

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Calling Java from Python Java Python jpype. Prev Next. Written by Gabor Szabo. Get this working first, then move on to the hard part! To get to python you need to embed an interpreter. Once you have that working, its time to make the horse and the monkey dance! I know I have not given you the fish, merely told you where to find the fish. Some pointers to note for this when compiling. When you compile boost you will need to compile a shared library.

And you need to include and link to the stuff you need from jdk, ie jawt. And yeah full on I know. There are so many ways in which this can go sour. So make sure you get each thing done block by block.

Then put them together. It's not smart to have python code inside java. Wrap your python code with flask or another web framework to make it a microservice. This makes your java program able to call this microservice e. This approach is simple and it will save you tons of issues. And the codes are loosely coupled so they are scalable. Updated on Mar 24th According to stx's comment, the above approach is not suitable for massive data transfer between client and server.

Several of the answers mention that you can use JNI or JNA to access cpython but I would not recommend starting from scratch because there are already open source libraries for accessing cpython from java. For example:. GraalVM is a good choice. They recently added support for python, I'd give it a try especially with how big its community has grown over the years.

GraalVM provides a Python 3. A primary goal of the GraalVM Python runtime is to support SciPy and its constituent libraries, as well as to work with other data science and machine learning libraries from the rich Python ecosystem.

At this point, the Python runtime is made available for experimentation and curious end-users. HOW TO? The Javabridge loads a Java class, org. CPython, that can be used to execute Python code. The class can be used within Java code called from the Python interpreter or it can be used within Java to run Python embedded in Java. The interpreter adds the builtin globals to the globals passed in, then executes the script. The same map may be used for both the locals and the globals - this mode may seem more familiar to those who regularly script in Python and expect the import statement to have a global effect.

There is no eval method. You can retrieve values by passing a container object such as an array or map as one of the locals and you can set elements in the object with values to be returned. You may want to maintain references to Python objects across script executions.