Category: How to use jython

This document provides an outline of an introductory course on programming in Jython and connecting Jython to Java. Jython is Python. That's one of its big advantages: you get two for the price of one. If your learn Python, then you have also learned Jython, and vice versa. If you already know Python, then you know Jython.

You will need Java installed, of course. And, since you are likely to want to use Jython class libraries from Jython, it is also likely that you will want the Java SDK. Important : If more than one version of Java is installed on your machine, make sure that when you install Jython, you use the version of Java for which the SDK is installed and the version of Java that you will be using when you run Jython.

Command line history -- On MS Windows, command line history for the Jython interactive interpreter comes built-in. Standalone mode -- You can also create a self-contained Jython jar file.

Run the standard installer abovethen you come to the "Installation type" page, select "Standalone". From within the Jython interactive interpreter or from within your Jython application, you can display the values of configuration properties.

Set these with the following:. See registry variable python.

how to use jython

To "set a breakpoint" in your code so that it will drop into debugger, either 1 use the b command at the pdb prompt or 2 add the following to your code at the location where you wish to drop into the debugger:. For more information on the Python debugger, see The Python Debugger in the Python standard documentation, or while in the debugger, type help.

Some Jython packages will be distributed as a Java jar file. If that is the case, add the jar file to your classpath. If the package is distributed as a standard Python package with a setup.

Special treatment for some overloaded Java methods -- Explicitly create and pass Jython objects. For example: the Jython for statement can be applied to Java collection objects.

Exercise -- Use the class java. Hashtable to create a dictionary with several keys and values, then print out the keys and their values. Example -- This sample extends the Java filestream class by adding a method that converts all characters to upper case You can make a Java class "act like" one of the built-in Jython classes. In order to do so, you would implement one or more of Jython's special methods. You can find descriptions of the special methods in the "Python Reference Manual": 3.

Example: This module implements a class that acts like a sequence in certain ways, specifically 1 it responds to the len operator by returning a length; 2 it supports an append method; and 3 it supports the use of the [] operator to get a value:.

Need to pay attention to data types, for example, on the Jython side. Use an explicit cast, for example, float 5. The ArgParser class helps us handle Jython keyword arguments.Download jython-standalone This library contains the PythonInterpreter class. Using the object of this class, any Python script can be executed using the execfile method. The PythonInterpreter enables you to make use of PyObjects directly.

All objects known to the Jython runtime system are represented by an instance of the class PyObject or one of its subclasses. The PythonInterpreter class has some regularly used methods, which are explained in the table given below.

Get the value of a variable in the local namespace. The value will be returned as an instance of the given Java class. It also shows how a Python variable can be set or read using set and get methods. Jython - Java Application Advertisements.

Previous Page. Next Page. Previous Page Print Page. Reader Set a java. Reader to use for the standard input stream. InputStream Set a java. InputStream to use for the standard input stream. Writer Set the java. Writer to use for the standard output stream. OutputStream Set the java. OutputStream to use for the standard output stream.

Writer Set a java. Writer to use for the standard error stream. OutputStream Set a java. OutputStream to use for the standard error stream. InputStream Execute an input stream of Python source in the local namespace.Jython is a Java implementation of Python that combines expressive power with clarity.

Jython is freely available for both commercial and non-commercial use and is distributed with source code under the PSF License v2. Jython is complementary to Java and is especially suited for the following tasks:. A more detailed introduction and reference can be found in the Jython Book. Jython is embedded in lots of projects. See some from MVNRepository.

What is Jython? Jython is complementary to Java and is especially suited for the following tasks: Embedded scripting - Java programmers can add the Jython libraries to their system to allow end users to write simple or complicated scripts that add functionality to the application.

Interactive experimentation - Jython provides an interactive interpreter that can be used to interact with Java packages or with running Java applications. This allows programmers to experiment and debug any Java system using Jython. Rapid application development - Python programs are typically x shorter than the equivalent Java program.

This translates directly to increased programmer productivity. The seamless interaction between Python and Java allows developers to freely mix the two languages both during development and in shipping products. Here is an example of running Python code inside a simple Java application import org.By using our site, you acknowledge that you have read and understand our Cookie PolicyPrivacy Policyand our Terms of Service.

The dark mode beta is finally here. Change your preferences any time. Stack Overflow for Teams is a private, secure spot for you and your coworkers to find and share information. I wrote a Python program that consists out of five. I want to execute the main of those python scripts from within a Java Application.

Jython - Using the Swing GUI library

What are my options to do so? Using the PythonInterpreter doesn't work, as for example the datetime module can't be loaded from Jython and I don't want the user to determine his Python path for those dependencies to work. I compiled the whole folder to.

Can I embed these. The command used in the java constructor should be the same as what you would type in a command line. For example:. Have a look at running scripts through processbuilder. Check the entry "use jython from java". I'm also interested in running Python code directly within Java, using Jythonand avoiding the need for an installed Python interpreter.

This function can then be executed either by creating a string that executes it, or by retrieving a pointer to the function and calling its call method with the correct parameters:. Learn more. Asked 4 years, 1 month ago. Active 1 year, 9 months ago. Viewed 5k times. CrushedPixel CrushedPixel 1 1 gold badge 10 10 silver badges 23 23 bronze badges.

I thought Jython was so you could include Java tooling into Python, not the other way around You can program primarily in either language and interoperate. Active Oldest Votes. Have a look at running scripts through processbuilder N. Sci Prog Sci Prog 2, 1 1 gold badge 5 5 silver badges 16 16 bronze badges. In this case again, I'd need to assure the user has Python 2.

That's not what I want, I'll have a look at Jython.

how to use jython

PythonInterpreter; import org. Big Rich Big Rich 4, 36 36 silver badges 57 57 bronze badges. My above answer is more inline with executing a particular function, within a Python script.

Jython Installation and Configuration

The answer at stackoverflow. I may amend my answer to reflect this new information.

how to use jython

Sign up or log in Sign up using Google. Sign up using Facebook. Sign up using Email and Password.Using the swing library in Jython is much easier compared to using it in Java. In Java the anonymous classes have to be used to create event binding. In Jython, we can simply pass a function for the same purpose. The basic top-level window is created by declaring an object of the JFrame class and set its visible property to true.

For that, the Jframe class needs to be imported from the swing package. The JFrame class has multiple constructors with varying number of arguments.

Jython Course Outline

We shall use the one, which takes a string as argument and sets it as the title. Store the following code as frame. Run the above script from the command prompt. It will display the following output showing a window. The swing GUI library is provided in the form of javax. A JColorChooser provides a pane of controls designed to allow a user to manipulate and select a color. A JCheckBox is a graphical component that can be in either an on true or off false state. The JRadioButton class is a graphical component that can be either in an on true or off false state.

A Scrollbar control represents a scroll bar component in order to enable the user to select from range of values. JOptionPane provides set of standard dialog boxes that prompt users for a value or informs them of something. As the task progresses towards completion, the progress bar displays the task's percentage of completion.

A JSpinner is a single line input field that lets the user select a number or an object value from an ordered sequence. Previous Page. Next Page. Previous Page Print Page. JList A JList component presents the user with a scrolling list of text items. JScrollbar A Scrollbar control represents a scroll bar component in order to enable the user to select from range of values.

JOptionPane JOptionPane provides set of standard dialog boxes that prompt users for a value or informs them of something. JProgressBar As the task progresses towards completion, the progress bar displays the task's percentage of completion.

JSlider A JSlider lets the user graphically select a value by sliding a knob within a bounded interval. JSpinner A JSpinner is a single line input field that lets the user select a number or an object value from an ordered sequence.Table of Contents. Look in the following places for general information:. Jython is invoked using the "jython" script, a short script that invokes your local JVM, sets the Java property install.

This is because "jython" is itself a script, and! Because there is no good platform-independent equivalent of the Windows Registry or Unix environment variables, Java has its own environment variable namespace. Jython aquires its namespace from the following sources later sources override defaults found in earlier places :. The following properties are recognized by Jython.

There may be others that aren't documented here; consult the comments in registry file for details. To find the Jython registry file and set the Python values for sys. Once the root directory is found, sys. Most Jython applications will want to use the vast array of Java packages available. The following documentation helps you work with Java packages. One of the goals of Jython is to make it as simple as possible to use existing Java libraries from Python.

The following example of an interactive session with Jython shows how a user could create an instance of the Java random number class found in java. Random and then interact with that instance. Hopefully, this example should make it clear that there are very few differences between using Java packages and using Python packages when working under Jython. There are a few things to keep in mind. You can create an instance of a Java class exactly the way you would create an instance of a Python class.

You must "call" the class with a set of arguments that is appropriate for one of the Java class's constructors. See the section below for more details on what constitutes appropriate arguments. Java classes have both static and instance methods this makes them behave much like a cross between a Python module and class.

As a user, you should rarely need to be concerned with this difference. Java methods and functions are called just exactly like their Python counterparts. There is some automatic type coercion that goes on both for the types being passed in and for the value returned by the method.

Jython - Java Application

The following table shows how Python objects are coerced to Java objects when passed as arguments in a function call.

The Java Types show the expected Java type for the argument, and the Allowed Python Types shows what Python objects can be converted to the given Java type. Notice the special behavior of String's when a java.

Object is expected. This behavior might change if it is shown to cause problems. Returned values from a Java method are also possibly coerced back to an object that is more readily usable in Python. The following table shows those coercions. Java methods are allowed to be overloaded for different signatures types and number of arguments.Jython is the JVM implementation of the Python programming language.

It is designed to run on the Java platform. A Jython program can import and use any Java class. Just as Java, Jython program compiles to bytecode. Jython, which started as JPython and was later renamed, follows closely the standard Python implementation called CPython as created by Guido Van Rossum. Jython was created in by Jim Hugunin. Jython 2. Since then, Jython 2. Development of Jython 3.

Python is a dynamically typed language. Hence, the type declaration of variable is not needed. Java on the other hand is a statically typed language, which means that the type declaration of variable is mandatory and cannot be changed.

Since Python is an interpreter-based language, it has no separate compilation steps. A Java program however needs to be compiled to bytecode and is in turn executed by a JVM. Python supports multiple inheritance, but in Java, multiple inheritance is not possible. It however has implementation of an interface. Compared to Java, Python has a richer built-in data structures lists, dicts, tuples, everything is an object.

how to use jython

Reference implementation of Python, called CPython, is written in C language. Jython on the other hand is completely written in Java and is a JVM implementation. Standard Python is available on multiple platforms. Jython is available for any platform with a JVM installed on it. Standard Python code compiles to a. Jython is truly multi-threaded in nature. Jython - Overview Advertisements.

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