Category: jython

Jython – Menus ”; Previous Next Most of the GUI based applications have a Menu bar at the top. It is found just below the title bar of the top-level window. The javax.swing package has elaborate facility to build an efficient menu system. It is constructed with the help of JMenuBar, JMenu and JMenuItem classes. In following example, a menu bar is provided in the top-level window. A File menu consisting of three menu item buttons is added to the menu bar. Let us now prepare a JFrame object with the layout set to BorderLayout. frame = JFrame(“JMenuBar example”) frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) frame.setLocation(100,100) frame.setSize(400,300) frame.setLayout(BorderLayout()) Now, a JMenuBar object is activated by the SetJMenuBar() method. bar = JMenuBar() frame.setJMenuBar(bar) Next, a JMenu object having ‘File’ caption is declared. Three JMenuItem buttons are added to the File menu. When any of the menu items are clicked, the ActionEvent handler OnClick() function is executed. It is defined with the actionPerformed property. file = JMenu(“File”) newfile = JMenuItem(“New”,actionPerformed = OnClick) openfile = JMenuItem(“Open”,actionPerformed = OnClick) savefile = JMenuItem(“Save”,actionPerformed = OnClick) file.add(newfile) file.add(openfile) file.add(savefile) bar.add(file) The OnClick() event handler retrieves the name of the JMenuItem button by the gwtActionCommand() function and displays it in the text box at the bottom of the window. def OnClick(event): txt.text = event.getActionCommand() The File menu object is added to menu bar. Finally, a JTextField control is added at the bottom of the JFrame object. txt = JTextField(10) frame.add(txt, BorderLayout.SOUTH) The entire code of menu.py is given below − from javax.swing import JFrame, JMenuBar, JMenu, JMenuItem, JTextField from java.awt import BorderLayout frame = JFrame(“JMenuBar example”) frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) frame.setLocation(100,100) frame.setSize(400,300) frame.setLayout(BorderLayout()) def OnClick(event): txt.text = event.getActionCommand() bar = JMenuBar() frame.setJMenuBar(bar) file = JMenu(“File”) newfile = JMenuItem(“New”,actionPerformed = OnClick) openfile = JMenuItem(“Open”,actionPerformed = OnClick) savefile = JMenuItem(“Save”,actionPerformed = OnClick) file.add(newfile) file.add(openfile) file.add(savefile) bar.add(file) txt = JTextField(10) frame.add(txt, BorderLayout.SOUTH) frame.setVisible(True) When the above script is executed using the Jython interpreter, a window with the File menu appears. Click on it and its three menu items will drop down. If any button is clicked, its name will be displayed in the text box control. Print Page Previous Next Advertisements ”;

Jython – Dialogs ”; Previous Next A Dialog object is a window that appears on top of the base window with which the user interacts. In this chapter, we shall see the preconfigured dialogs defined in the swing library. They are MessageDialog, ConfirmDialog and InputDialog. They are available because of the static method of the JOptionPane class. In the following example, the File menu has three JMenu items corresponding to the above three dialogs; each executes the OnClick event handler. file = JMenu(“File”) msgbtn = JMenuItem(“Message”,actionPerformed = OnClick) conbtn = JMenuItem(“Confirm”,actionPerformed = OnClick) inputbtn = JMenuItem(“Input”,actionPerformed = OnClick) file.add(msgbtn) file.add(conbtn) file.add(inputbtn) The OnClick() handler function retrieves the caption of Menu Item button and invokes the respective showXXXDialog() method. def OnClick(event): str = event.getActionCommand() if str == ”Message”: JOptionPane.showMessageDialog(frame,”this is a sample message dialog”) if str == “Input”: x = JOptionPane.showInputDialog(frame,”Enter your name”) txt.setText(x) if str == “Confirm”: s = JOptionPane.showConfirmDialog (frame, “Do you want to continue?”) if s == JOptionPane.YES_OPTION: txt.setText(“YES”) if s == JOptionPane.NO_OPTION: txt.setText(“NO”) if s == JOptionPane.CANCEL_OPTION: txt.setText(“CANCEL”) If the message option from menu is chosen, a message pops up. If Input option is clicked, a dialog asking for the input pops up. The input text is then displayed in the text box in the JFrame window. If the Confirm option is selected, a dialog with three buttons, YES, NO and CANCEL comes up. The user’s choice is recorded in the text box. The entire code is given below − from javax.swing import JFrame, JMenuBar, JMenu, JMenuItem, JTextField from java.awt import BorderLayout from javax.swing import JOptionPane frame = JFrame(“Dialog example”) frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) frame.setLocation(100,100) frame.setSize(400,300) frame.setLayout(BorderLayout()) def OnClick(event): str = event.getActionCommand() if str == ”Message”: JOptionPane.showMessageDialog(frame,”this is a sample message dialog”) if str == “Input”: x = JOptionPane.showInputDialog(frame,”Enter your name”) txt.setText(x) if str == “Confirm”: s = JOptionPane.showConfirmDialog (frame, “Do you want to continue?”) if s == JOptionPane.YES_OPTION: txt.setText(“YES”) if s == JOptionPane.NO_OPTION: txt.setText(“NO”) if s == JOptionPane.CANCEL_OPTION: txt.setText(“CANCEL”) bar = JMenuBar() frame.setJMenuBar(bar) file = JMenu(“File”) msgbtn = JMenuItem(“Message”,actionPerformed = OnClick) conbtn = JMenuItem(“Confirm”,actionPerformed = OnClick) inputbtn = JMenuItem(“Input”,actionPerformed = OnClick) file.add(msgbtn) file.add(conbtn) file.add(inputbtn) bar.add(file) txt = JTextField(10) frame.add(txt, BorderLayout.SOUTH) frame.setVisible(True) When the above script is executed, the following window is displayed with three options in the menu − Message box Input Box Confirm Dialog Print Page Previous Next Advertisements ”;

Discuss Jython ”; Previous Next Jython is the JVM implementation of the Python programming language. It is designed to run on the Java platform. Jython was created in 1997 by Jim Hugunin. It closely follows the standard Python implementation called CPython. Jython 2.7.0 was released in May 2015, which corresponds to CPython 2.7. This is an introductory tutorial, which covers the basics of Jython and explains how to handle its various modules and sub-modules. Print Page Previous Next Advertisements ”;

Jython – Useful Resources ”; Previous Next The following resources contain additional information on Jython. Please use them to get more in-depth knowledge on this. Useful Links on Jython Jython − Jython Official Website. Jython Wiki − Wikipedia Reference for Jython. Useful Books on Jython To enlist your site on this page, please drop an email to [email protected] Print Page Previous Next Advertisements ”;

Jython – Servlets ”; Previous Next A Java servlet is the most widely used web development technique. We can use Jython to write servlets and this adds many more advantages beyond what Java has to offer because now we can make use of the Python language features as well. We shall use the NetBeans IDE to develop a Java web application with a Jython servlet. Ensure that the nbPython plugin is installed in the NetBeans installation. Start a new project to build a web application by choosing the following path – File → New Project → Java web → New Web Application. Provide the Project name and location. The IDE will create the project folder structure. Add a Java servlet file (ServletTest.java) under the source packages node in the Projects window. This will add servlet-api.jar in the lib folder of the project. Also, let the IDE create the web.xml descriptor file. Add the following code in ServletTest.java. import java.io.*; import javax.servlet.*; import javax.servlet.http.*; public class ServletTest extends HttpServlet { public void doGet (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { doPost(request, response); } public void doPost (HttpServletRequest request, HttpServletResponse response) throws ServletException, IOException { response.setContentType (“text/html”); PrintWriter toClient = response.getWriter(); toClient.println ( “<html> <head> <title>Servlet Test</title>” + ” </head> <body> <h1>Servlet Test</h1> </body> </html>” ); } } The web.xml file created by NetBeans will be as shown below − <web-app> <servlet> <servlet-name>ServletTest</servlet-name> <servlet-class>ServletTest</servlet-class> </servlet> <servlet-mapping> <servlet-name>ServletTest</servlet-name> <url-pattern>/ServletTest</url-pattern> </servlet-mapping> </web-app> Build and run the project to obtain the text Servlet Test appearing in <h1> tag in the browser window. Thus, we have added a regular Java servlet in the application. Now, we shall add the Jython Servlet. Jython servlets work by means of an intermediate Java servlet is also known as PyServlet. The PyServlet.class is present in the jython standalone.jar. Add it in the WEB-INF/lib folder. The next step is to configure the web.xml to invoke the PyServlet, whenever a request for any *.py file is raised. This should be done by adding the following xml code in it. <servlet> <servlet-name>PyServlet</servlet-name> <servlet-class>org.python.util.PyServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>PyServlet</servlet-name> <url-pattern>*.py</url-pattern> </servlet-mapping> The full web.xml code will look as shown below. <web-app> <servlet> <servlet-name>ServletTest</servlet-name> <servlet-class>ServletTest</servlet-class> </servlet> <servlet> <servlet-name>PyServlet</servlet-name> <servlet-class>org.python.util.PyServlet</servlet-class> <load-on-startup>1</load-on-startup> </servlet> <servlet-mapping> <servlet-name>ServletTest</servlet-name> <url-pattern>/ServletTest</url-pattern> </servlet-mapping> <servlet-mapping> <servlet-name>PyServlet</servlet-name> <url-pattern>*.py</url-pattern> </servlet-mapping> </web-app> Place the following Jython code in the WEB-INF folder inside the project folder as JythonServlet.py, which is equivalent to the previous ServletTest.java. from javax.servlet.http import HttpServlet class JythonServlet1 (HttpServlet): def doGet(self,request,response): self.doPost (request,response) def doPost(self,request,response): toClient = response.getWriter() response.setContentType (“text/html”) toClient.println ( “<html> <head> <title>Servlet Test</title>” + ” </head> <body> <h1>Servlet Test</h1> </body> </html>” ) Build the project and in the browser open the following URL − http://localhost:8080/jythonwebapp/jythonservlet.py The browser will show the Servlet Test in <h1> tag as in case of Java Servlet output. Print Page Previous Next Advertisements ”;

Jython – NetBeans Plugin and Project ”; Previous Next Python and Jython support for NetBeans is available via the nbPython plugin. Download the plugin from following URL – http://plugins.netbeans.org/plugin/56795. Unzip the downloaded archive in some folder. For example – d:nbplugin. To install the NetBeans Plugin, let us follow the steps given below. Step 1 − Start the Netbeans IDE and then go to Tools/Plugin to open the Plugin Manager. Choose ‘Downloaded’ tab and browse to the folder in which the downloaded file has been unzipped. The NetBeans window will appear as shown below. Step 2 − The next step is to select all the .nbm files and click open. Step 3 − Click on the Install button. Step 4 − Accept the following license agreement to continue. Ignore the warning about untrusted source of plugins and restart the IDE to proceed. Jython Project in NetBeans Once restarted, start a new project by choosing File/New. Python category will now be available in the categories list. Choose it to proceed. If the system has Python installed, its version/versions will be automatically detected and shown in the Python platform dropdown list. However, Jython will not be listed. Click on the Manage button to add it. Click on the ‘New’ button to add a platform name and path to Jython executable. Jython will now be available in the platform list. Select from the dropdown list as shown in the following screenshot. We can now fill in the project name, location and main file in the next window. The project structure will appear in the projects window of the NetBeans IDE and a template Python code in the editor window. Build and execute the Jython project to obtain the following result in the output window of the NetBeans IDE. Print Page Previous Next Advertisements ”;

Jython – A Project in Eclipse ”; Previous Next To make a project in eclipse, we should follow the steps given below. Step 1 − Choose File ? New ? Project. Choose PyDev from the filter dialog. Give project name, project type and click on Finish. Step 2 − Hello project will now appear in the project explorer on the left. Right click to add hello.py in it. Step 3 − An empty hello.py will appear in the editor. Write the Jython code and save. Step 4 − Click on the Run button on the menu bar. The output will appear in the console window as shown below. Print Page Previous Next Advertisements ”;

Jython – Using the Swing GUI library ”; Previous Next One of the major features of Jython is its ability to use the Swing GUI library in JDK. The Standard Python distribution (often called as CPython) has the Tkinter GUI library shipped with it. Other GUI libraries like PyQt and WxPython are also available for use with it, but the swing library offers a platform independent GUI toolkit. 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. from javax.swing import JFrame The JFrame class has multiple constructors with varying number of arguments. We shall use the one, which takes a string as argument and sets it as the title. frame = JFrame(“Hello”) Set the frame’s size and location properties before setting its visible property to true. Store the following code as frame.py. from javax.swing import JFrame frame = JFrame(“Hello”) frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) frame.setLocation(100,100) frame.setSize(300,200) frame.setVisible(True) 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.swing package in Java. Its main container classes, JFrame and JDialog are respectively derived from Frame and Dialog classes, which are in the AWT library. Other GUI controls like JLabel, JButton, JTextField, etc., are derived from the JComponent class. The following illustration shows the Swing Package Class hierarchy. The following table summarizes different GUI control classes in a swing library − Sr.No. Class & Description 1 JLabel A JLabel object is a component for placing text in a container. 2 JButton This class creates a labeled button. 3 JColorChooser A JColorChooser provides a pane of controls designed to allow a user to manipulate and select a color. 4 JCheckBox A JCheckBox is a graphical component that can be in either an on (true) or off (false) state. 5 JRadioButton The JRadioButton class is a graphical component that can be either in an on (true) or off (false) state. in a group. 6 JList A JList component presents the user with a scrolling list of text items. 7 JComboBox A JComboBox component presents the user with drop down list of items 8 JTextField A JTextField object is a text component that allows for the editing of a single line of text. 9 JPasswordField A JPasswordField object is a text component specialized for password entry. 10 JTextArea A JTextArea object is a text component that allows editing of a multiple lines of text. 11 ImageIcon A ImageIcon control is an implementation of the Icon interface that paints Icons from Images 12 JScrollbar A Scrollbar control represents a scroll bar component in order to enable the user to select from range of values. 13 JOptionPane JOptionPane provides set of standard dialog boxes that prompt users for a value or informs them of something. 14 JFileChooser A JFileChooser control represents a dialog window from which the user can select a file. 15 JProgressBar As the task progresses towards completion, the progress bar displays the task”s percentage of completion. 16 JSlider A JSlider lets the user graphically select a value by sliding a knob within a bounded interval. 17 JSpinner A JSpinner is a single line input field that lets the user select a number or an object value from an ordered sequence. We would be using some of these controls in subsequent examples. Print Page Previous Next Advertisements ”;

Jython – Event Handling ”; Previous Next Event handling in Java swing requires that the control (like JButton or JList etc.) should be registered with the respective event listener. The event listener interface or corresponding Adapter class needs to be either implemented or subclassed with its event handling method overridden. In Jython, the event handling is very simple. We can pass any function as property of event handling function corresponding to the control. Let us first see how a click event is handled in Java. To begin with, we have to import the java.awt.event package. Next, the class extending JFrame must implement ActionListener interface. public class btnclick extends JFrame implements ActionListener Then, we have to declare the JButton object, add it to the ContentPane of frame and then register it with ActionListener by the addActionListener() method. JButton b1 = new JButton(“Click here”); getContentPane().add(b1); b1.addActionListener(this); Now, the actionPerformed() method of the ActionListener interface must be overridden to handle the ActionEvent. Following is entire Java code − import java.awt.event.*; import javax.swing.*; public class btnclick extends JFrame implements ActionListener { btnclick() { JButton b1 = new JButton(“Click here”); getContentPane().add(b1); b1.addActionListener(this); } public void actionPerformed(ActionEvent e) { System.out.println(“Clicked”); } public static void main(String args[]) { btnclick b = new btnclick(); b.setSize(300,200); b.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE); b.setVisible(true); } } Now, we will write the Jython code equivalent to the same code. To start with, we do not need to import the ActionEvent or the ActionListener, since Jython’s dynamic typing allows us to avoid mentioning these classes in our code. Secondly, there is no need to implement or subclass ActionListener. Instead, any user defined function is straightaway provided to the JButton constructor as a value of actionPerformed bean property. button = JButton(”Click here!”, actionPerformed = clickhere) The clickhere() function is defined as a regular Jython function, which handles the click event on the button. def change_text(event): print clicked!” Here is the Jython equivalent code. from javax.swing import JFrame, JButton frame = JFrame(“Hello”) frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) frame.setLocation(100,100) frame.setSize(300,200) def clickhere(event): print “clicked” btn = JButton(“Add”, actionPerformed = clickhere) frame.add(btn) frame.setVisible(True) The Output of Java and Jython code is identical. When the button is clicked, it will print the ‘clicked’ message on the console. In the following Jython code, two JTextField objects are provided on the JFrame window to enter marks in ‘phy’ and ‘maths’. The JButton object executes the add() function when clicked. btn = JButton(“Add”, actionPerformed = add) The add() function reads the contents of two text fields by the getText() method and parses them to integers, so that, addition can be performed. The result is then put in the third text field by the setText() method. def add(event): print “add” ttl = int(txt1.getText())+int(txt2.getText()) txt3.setText(str(ttl)) The complete code is given below − from javax.swing import JFrame, JLabel, JButton, JTextField from java.awt import Dimension frame = JFrame(“Hello”) frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) frame.setLocation(100,100) frame.setSize(300,200) frame.setLayout(None) def add(event): print “add” ttl = int(txt1.getText())+int(txt2.getText()) txt3.setText(str(ttl)) lbl1 = JLabel(“Phy”) lbl1.setBounds(60,20,40,20) txt1 = JTextField(10) txt1.setBounds(120,20,60,20) lbl2 = JLabel(“Maths”) lbl2.setBounds(60,50,40,20) txt2 = JTextField(10) txt2.setBounds(120, 50, 60,20) btn = JButton(“Add”, actionPerformed = add) btn.setBounds(60,80,60,20) lbl3 = JLabel(“Total”) lbl3.setBounds(60,110,40,20) txt3 = JTextField(10) txt3.setBounds(120, 110, 60,20) frame.add(lbl1) frame.add(txt1) frame.add(lbl2) frame.add(txt2) frame.add(btn) frame.add(lbl3) frame.add(txt3) frame.setVisible(True) When the above code is executed from the command prompt, the following window appears. Enter marks for ‘Phy’, Maths’, and click on the ‘Add’ button. The result will be displayed accordingly. Jython JRadioButton Event The JRadioButton class is defined in the javax.swing package. It creates a selectable toggle button with on or off states. If multiple radio buttons are added in a ButtonGroup, their selection is mutually exclusive. In the following example, two objects of the JRadioButton class and two JLabels are added to a Jpanel container in a vertical BoxLayout. In the constructor of the JRadioButton objects, the OnCheck() function is set as the value of the actionPerformed property. This function is executed when the radio button is clicked to change its state. rb1 = JRadioButton(“Male”, True,actionPerformed = OnCheck) rb2 = JRadioButton(“Female”, actionPerformed = OnCheck) Note that the default state of Radio Button is false (not selected). The button rb1 is created with its starting state as True (selected). The two radio buttons are added to a radio ButtonGroup to make them mutually exclusive, so that if one is selected, other is deselected automatically. grp = ButtonGroup() grp.add(rb1) grp.add(rb2) These two radio buttons along with two labels are added to a panel object in the vertical layout with a separator area of 25 pixels in heights between rb2 and lbl2. panel = JPanel() panel.setLayout(BoxLayout(panel, BoxLayout.Y_AXIS)) panel.add(Box.createVerticalGlue()) panel.add(lbl) panel.add(rb1) panel.add(rb2) panel.add(Box.createRigidArea(Dimension(0,25))) panel.add(lbl1) This panel is added to a top-level JFrame object, whose visible property is set to ‘True’ in the end. frame = JFrame(“JRadioButton Example”) frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) frame.setLocation(100,100) frame.setSize(250,200) frame.setVisible(True) The complete code of radio.py is given below: from javax.swing import JFrame, JPanel, JLabel, BoxLayout, Box from java.awt import Dimension from javax.swing import JRadioButton,ButtonGroup frame = JFrame(“JRadioButton Example”) frame.setDefaultCloseOperation(JFrame.EXIT_ON_CLOSE) frame.setLocation(100,100) frame.setSize(250,200) panel = JPanel() panel.setLayout(BoxLayout(panel, BoxLayout.Y_AXIS)) frame.add(panel) def OnCheck(event): lbl1.text = “” if rb1.isSelected(): lbl1.text = lbl1.text+”Gender selection : Male” else: lbl1.text = lbl1.text+”Gender selection : Female ” lbl = JLabel(“Select Gender”) rb1 = JRadioButton(“Male”, True,actionPerformed = OnCheck) rb2 = JRadioButton(“Female”, actionPerformed = OnCheck) grp = ButtonGroup() grp.add(rb1) grp.add(rb2) lbl1 = JLabel(“Gender Selection :”) panel.add(Box.createVerticalGlue()) panel.add(lbl) panel.add(rb1) panel.add(rb2) panel.add(Box.createRigidArea(Dimension(0,25))) panel.add(lbl1) frame.setVisible(True) Run the above Jython script and change the radio button selection. The selection will appear in the label at the bottom. Jython JCheckBox Event Like the JRadioButton, JCheckBox object is also a selectable button with a rectangular checkable box besides its caption. This is generally used to provide user opportunity to select multiple options from the list of items. In the following example, two check boxes and a label from swing package are added to a JPanel in vertical BoxLayout. The label at bottom displays the instantaneous selection state of two check boxes. Both checkboxes are declared with the constructor having the actionPerformed property set to the OnCheck() function. box1 = JCheckBox(“Check1”, actionPerformed = OnCheck) box2 = JCheckBox(“Check2”, actionPerformed = OnCheck) The OnCheck() function verifies selection

Jython – Quick Guide ”; Previous Next Jython – Overview 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. One of the main advantages is that a user interface designed in Python can use GUI elements of AWT, Swing or SWT Package. 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 1997 by Jim Hugunin. Jython 2.0 was released in 1999. Since then, Jython 2.x releases correspond to equivalent CPython releases. Jython 2.7.0 released in May 2015, corresponds to CPython 2.7. Development of Jython 3.x is under progress. Difference between Python and Java Following are the differences between Python and Java − 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. Python has only unchecked exceptions, whereas Java has both checked and unchecked exceptions. Python uses indents for scoping, while Java uses matching curly brackets. 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). Difference between Python and Jython Following are the differences between Python and 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 .pyc file, while Jython program compiles to a .class file. Python extensions can be written in C language. Extensions for Jython are written in Java. Jython is truly multi-threaded in nature. Python however uses the Global Interpreter Lock (GIL) mechanism for the purpose. Both implementations have different garbage collection mechanisms. In the next chapter, we will learn how to import the Java libraries in Jython. Jython – Installation Before installation of Jython 2.7, ensure that the system has JDK 7 or more installed. Jython is available in the form of an executable jar file. Download it from – https://www.jython.org/download.html and either double click on its icon or run the following command − java -jar jython_installer-2.7.0.jar An installation wizard will commence with which installation options have to be given. Here is the systematic installation procedure. The first step in the wizard asks you to select the language. The second step prompts you to accept the licence agreement. In the next step, choose the installation type. It is recommended to choose the Standard installation. The next screen asks your confirmation about your options and proceeds to complete the installation. The installation procedure might take some time to complete. After the installation is complete, invoke jython.exe from the bin directory inside the destination directory. Assuming that Jython is installed in C:jython27, execute the following from the command line. C:jython27binjython A Python prompt (>>>) will appear, in front of which any Python statement or Python script can be executed. Jython – Importing Java Libraries One of the most important features of Jython is its ability to import Java classes in a Python program. We can import any java package or class in Jython, just as we do in a Java program. The following example shows how the java.util packages are imported in Python (Jython) script to declare an object of the Date class. Live Demo from java.util import Date d = Date() print d Save and run the above code as UtilDate.py from the command line. Instance of the current date and time will be displayed. C:jython27bin>jython UtilDate.py Sun Jul 09 00:05:43 IST 2017 The following packages from the Java library are more often imported in a Jython program mainly because standard Python library either does not have their equivalents or are not as good. Servlets JMS J2EE Javadoc Swing is considered superior to other GUI toolkits Any Java package for that matter can be imported in a Jython script. Here, the following java program is stored and compiled in a package called foo. package foo; public class HelloWorld { public void hello() { System.out.println(“Hello World!”); } public void hello(String name) { System.out.printf(“Hello %s!”, name); } } This HelloWorld.class is imported in the following Jython Script. Methods in this class can be called from the Jython script importex.py. from foo import HelloWorld h = HelloWorld() h.hello() h.hello(“TutorialsPoint”) Save and execute the above script from the command line to get following output. C:jython27bin>jython importex.py Hello World! Hello TutorialsPoint! Jython – Variables and Data Types Variables are named locations in computer’s memory. Each variable can hold one piece of data in it. Unlike Java, Python is a dynamically typed language. Hence while using Jython also; prior declaration of data type of variable is not done. Rather than the type of variable deciding which data can be stored in it, the data decides the type of variable. In the following example, a variable is assigned an integer value. Using the type() built-in function, we can verify that the type of variable is an integer. But, if the same variable is assigned a string, the type() function will string as the type of same variable. > x = 10 >>> type(x) <class ”int”> >>> x = “hello” >>> type(x) <class ”str”> This explains why Python is called a dynamically typed language. The following Python built-in data types can also be used in Jython − Number String List Tuple Dictionary Python recognizes numeric