How to integrate 2 languages using python robotframework

I have some libraries written in java how to use that java functions in python-robotframework

Multiple options.

Option 1:
Use the jrobotremoteserver to serve a Keyword Library (written in Java) to Robot Framework
You can find some Java Library example snippets only in the older User Guides , since Java was no longer supported with Robot Framework 5 (as Python2/Jython was no longer supported).
But serving such libraries via jrobotremoteserver would still be possible.

Option 2:
Use JPype

If you want to use Java (e.g. to develop a Keyword Library) I recommend to look into JPype.

However, if I understand correctly you would still need to compile and package that file in a .jar.

An example. It’s just a calculator in java and the methods are called from Robot

JavaWrapper.py

# Boiler plate stuff to start the module
import jpype
import jpype.imports
from jpype.types import *
from inspect import getmembers, isfunction

# Launch the JVM
jpype.startJVM(classpath=['library/exercise/solution/JavaLibrary.jar'])

from org.calculator import JavaLibrary

class JavaWrapper:

    def get_keyword_names(self):
        for name, func in getmembers(JavaLibrary, isfunction):
            if name.startswith('_'):
                continue
            yield name

    def run_keyword(self, name, args, kwargs):
        print("Running keyword '%s' with positional arguments %s and named arguments %s."
              % (name, args, kwargs))
        func = getattr(JavaLibrary, name)
        return func(*args, **kwargs)

JavaLibrary.java

package org.calculator;
/*
 * A class which provides functions for all basic arithmetic operations
 * add, subtract, multiply, divide, and remainder.
 */
public class JavaLibrary {
    public static int add(int a, int b) {
		return a + b;
	}
	public static int subtract(int a, int b) {
		return a - b;
	}
	public static int multiply(int a, int b) {
		return a * b;
	}
	public static int divide(int a, int b) {
		return a / b;
	}
	public static int remainder(int a, int b) {
		return a % b;
	}
}

test.robot

*** Settings ***
Library    JavaWrapper.py

*** Test Cases ***
Use Dynamic Library
    ${result}    Add    ${1}    ${2}
    Log    ${result}
    ${result}    Subtract    ${3}    ${1}
    Log    ${result}