All I'm trying to do is pass an argument to the python interpreter so it can be passed as an argument for a module.
E.g. I have the following defined in a py file:
def print_twice(test):
print test
print test
I want to pass it the argument "Adam", so I've tried:
// Create an instance of the PythonInterpreter
PythonInterpreter interp = new PythonInterpreter();
// The exec() method executes strings of code
interp.exec("import sys");
interp.exec("print sys");
PyCode pyTest = interp.compile("Adam", "C:/Users/Adam/workspace/JythonTest/printTwice.py");
System.out.println(pyTest.toString());
I've also tried:
interp.eval("print_twice('Adam')");
I've been using the following Jython API but I don't understand it well:
http://www.jython.org/javadoc/org/python/util/PythonInterpreter.html#compile%28java.lang.String,%20java.lang.String%29
I would be very grateful for your advices.
Thank you
This should work:
interp.exec("import YOUR_PYTHON_FILE.py");
interp.exec("YOUR_PYTHON_FILE.print_twice('Adam')");
Its equivalent in a python console is this:
>>> import YOUR_PYTHON_FILE.py
>>> YOUR_PYTHON_FILE.print_twice('Adam')
Adam
Adam
You shouldn't need to explicitly compile the script, just import it and the interpreter will take care of compilation. Something like this (assuming printTwice.py is in the working directory of your program:
interp.exec("from printTwice import print_twice");
interp.exec("print_twice('Adam')");
You don't need to use interp.eval on the second line assuming that print_twice does actually contain print statements; if it just returns a string then you probably want
System.out.println(interp.eval("print_twice('Adam')"));.
Related
I am trying to develop a simple Java application and I want it to use some Python code using Jython. I am trying to run a python method from a file and getting this error:
ImportError: cannot import name testFunction
Just trying a simple example so I can see where the problem is. My python file test.py is like this:
def testFunction():
print("testing")
And my Java class:
PythonInterpreter interpreter = new PythonInterpreter();
interpreter.exec("path_to_file\\test.py");
interpreter.exec("from test import testFunction");
So it can correctly find the module but behaves like there is no function called testFunction inside.
Execute script files as follows.
interpreter.execfile("path/to/file/test.py");
If you have functions declared in the script file then after executing the above statement you'll have those functions available to be executed from the program as follows.
interpreter.exec("testFunction()");
So, you don't need to have any import statement.
Complete Sample Code:
package jython_tests;
import org.python.util.PythonInterpreter;
public class RunJythonScript2 {
public static void main(String[] args) {
try (PythonInterpreter pyInterp = new PythonInterpreter()) {
pyInterp.execfile("scripts/test.py");
pyInterp.exec("testFunction()");
}
}
}
Script:
def testFunction():
print "testing"
Output:
testing
String printcode = "(print "foo")";
If I have the above String in java, is there anyway to execute it by clojure inside the Java ?
The following should work (assuming that you have properly set up dependencies and initialised the Clojure runtime):
import clojure.lang.RT;
import clojure.lang.Compiler;
...
Compiler.eval(RT.readString("(print \"foo\")")));
I'm building a Python UI using Tkinter. For the needs of the program, I've to connect Python with Java to do some stuff, so I'm using a simple Jython script as a linker. I cant use Tkinter with Jython because it's not supported.
Python (ui.py) -> Jython (linker.py) -> Java (compiled in jars)
To call the Jython function in Python I use subprocess as follows:
ui.py:
cmd = 'jython linker.py"'
my_env = os.environ
my_env["JYTHONPATH"] = tons_of_jars
subprocess.Popen(cmd, shell=True, env=my_env)
Then, in the Jython file, linker.py, I import the Java classes already added on the JYTHONPATH, and I create an object with the name m and call to some functions of the Java class.
linker.py:
import handler.handler
m = handler.handler(foo, moo, bar)
m.schedule(moo)
m.getFullCalendar()
m.printgantt()
The thing is that I've created a m object, that will be destroyed after the execution of jython linker.py ends.
So the question is: Is possible to save that m object somewhere so I can call it from ui.py whenever I want? If it's not possible, is there any other way to do this?
Thanks in advance.
I finally solved it by using ObjectOutputStream.
from java import io
def saveObject(x, fname="object.bin"):
outs = io.ObjectOutputStream(io.FileOutputStream(fname))
outs.writeObject(x)
outs.close()
def loadObject(fname="object.bin"):
ins = io.ObjectInputStream(io.FileInputStream(fname))
x=ins.readObject()
ins.close()
return x
This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
Calling Java app with “subprocess” from Python and reading the Java app output
Basically what I am looking for is, I want to interact with java program while its running using python so I can access its output and pass input to it.
I have managed to run a Java program using python. I want to know can i access the outputs of java program in my python program.
For example.
In java program: System.out.println("Enter no.");
In python i should be able to get "Enter no" as string and also pass value to java program from python.a
What I managed to do till no :
Python program :
import sys
import os.path,subprocess
def compile_java(java_file):
subprocess.check_call(['javac', java_file])
def execute_java(java_file):
java_class,ext = os.path.splitext(java_file)
cmd = ['java', java_class]
subprocess.call(cmd, shell=False)
def run_java(java_file):
compile_java(java_file)
execute_java(java_file)
Java Program :
import java.io.*;
import java.util.*;
class Hi
{
public static void main(String args[])throws IOException
{
Scanner t=new Scanner(System.in);
System.out.println("Enter any integer");
int str1=t.nextInt();
System.out.println("You entered"+str1);
}
}
Thanx :)
If all you need is to get the output from a non-interactive execution of your Java program, use subprocess.check_output instead of subprocess.call.
http://docs.python.org/library/subprocess.html
You need Python 2.7 or newer for check_output to be available.
If you need to interact with the Java program, you can do so using Popen.communicate, where you can read the process's output and send stuff to its input using file descriptors.
You can also use the pexpect python library to automate this kind of interaction, pexpect abstracts a lot of the legwork involved in using Popen.communicate.
Note that these techniques apply for any kind of executable you need your Python program to interact with, not just Java; as long as it uses stdin and stdout, using these calls should work for you.
The easiest way would be to use Jython, which is a complete Python implementation that runs in the JVM, and can interact with native Java code. But if you want to use CPython, and generally continue down the path you've sketched out above, you'll want to create a live Python Popen object that you can interact with. For example:
import sys
import os.path,subprocess
def compile_java(java_file):
subprocess.check_call(['javac', java_file])
def execute_java(java_file):
java_class,ext = os.path.splitext(java_file)
cmd = ['java', java_class]
return subprocess.Popen(cmd, shell=True, stdin=subprocess.PIPE, stdout=subprocess.PIPE)
def run_java(java_file):
compile_java(java_file)
process = execute_java(java_file)
for i in range(10):
process.stdin.write(str(i) + "\n")
This question already has answers here:
Closed 12 years ago.
Possible Duplicate:
How to run a python script from java?
I am running a Python script using Jython and got this error:
Exception in thread "main" Traceback (innermost last): File "C:\Facebook\LoginPython\Facebook.py", line 5, in ? ImportError: no module named cookielib
Why doesn't this work?
A little bit more about using Jython - had my share of problems with that as well. Note that this may not be the best way to do it, but it works fine for me.
I assume you want to call a function foo in module bar from your Java code that takes a string argument and returns a string:
PythonInterpreter interpreter = new PythonInterpreter();
// Append directory containing module to python search path and import it
interpreter.exec("import sys\n" + "sys.path.append(pathToModule)\n" +
"from bar import foo");
PyObject meth = interpreter.get("foo");
PyObject result = meth.__call__(new PyString("Test!"));
String real_result = (String) result.__tojava__(String.class);
The sys.path.append() part is only necessary if your module isn't part of the Python search path by default, which may very well be the problem if you get Import or Module not find errors.
Also you need to cast the objects between the java and python versions, you'll need to look that up if necessary, so far I only needed primitive types that were easy to cast, not sure if it's as easy for arbitrary java objects.
Use Jython to run Python on the JVM. Use PyDev to develop with Python (or Jython) on Eclipse.