Java issues

[jousheinfo]

Hello, Im trying to run a code using neqsim for plotting phase envelope of a CO2 mixture, but I keep getting the following error:

AttributeError: Java package 'neqsim' is not valid

I have in Environment Variables:

C:\Users\xxx\AppData\Local\Programs\Eclipse Adoptium\jdk-25.0.1.8-hotspot\bin

I have installed Eclipse Temurin as suggested in the description, and I have also installed jpype by using conda install -c conda-forge jpype1. I have also given the paths in the code as shown below, but I keep getting the same error: AttributeError: Java package 'neqsim' is not valid

Please help, I dont know what else to do.

import os
import jpype
import matplotlib.pyplot as plt

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1) JVM path (from JPype)

-----------------------------

jvm_path = jpype.getDefaultJVMPath()
print("Using JVM:", jvm_path)

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2) NeqSim JAR paths (from your dir output)

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jar_java11 = r"C:\Users\xxx\anaconda3\Lib\site-packages\neqsim\lib\java11\neqsim-3.1.3.jar"
jar_java8 = r"C:\Users\xxx\anaconda3\Lib\site-packages\neqsim\lib\java8\neqsim-3.1.3-Java8.jar"

Join them into a single classpath string

classpath = os.pathsep.join([jar_java11, jar_java8])
print("Using classpath:", classpath)

-----------------------------

3) Start JVM with NeqSim jars

-----------------------------

if not jpype.isJVMStarted():
jpype.startJVM(
jvm_path,
"-ea",
f"-Djava.class.path={classpath}",
convertStrings=False,
)
print("JVM started with NeqSim jars")

-----------------------------

4) Now import NeqSim thermo tools

(do NOT import neqsim before startJVM)

-----------------------------

from neqsim.thermo.thermoTools import *

-----------------------------

5) Build CO2–N2 mixture and plot PT envelope

-----------------------------

gas = fluid("srk") # SRK EOS
gas.addComponent("CO2", 0.7) # 70% CO2
gas.addComponent("nitrogen", 0.3) # 30% N2
gas.setMixingRule(2) # classic mixing rule

plt.figure(figsize=(8, 6))
phaseenvelope(gas, True) # True => P–T envelope plot

plt.title("P–T phase envelope – CO$_2$/N$_2$ (0.7 / 0.3)")
plt.xlabel("Temperature [K]")
plt.ylabel("Pressure [bar]")
plt.show()