[program-l] Fruit basket program in Jython

http://EmpowermentZone.com/jvm_fruit.zip
This is an update to my collection of fruit basket programs that run on the Java Virtual Machine (JVM). It adds the Jython language, which currently implements Python 2.5 on the JVM.
Jython syntax includes conveniences such as property initializers in the call to a class constructor method. The fact that functions are objects enables them to be passed as a value where an event handler is expected.
Besides the additional Jython code, this distribution adds to the description of these JVM languages and their ecosystem. The main text file is appended to the body of this message. 

Jamal

----------

From the archive
http://EmpowermentZone.com/jvm_fruit.zip
These fruit basket programs are written with languages that target the cross-platform Java Virtual Machine (JVM). They use the Standard Widget Toolkit (SWT), a GUI library that wraps native controls of the operating system, which implement its baseline accessibility API: Microsoft Active Accessibility on Windows, the Assistive Technology Service Provider Interface on Linux/GNOME, and the Apple Accessibility Protocol on the Mac. On Windows, the Java Access Bridge is not needed for use with a screen reader. SWT is available from 
http://eclipse.org/swt
Five different languages implement essentially the same fruit basket program: Java, 
http://java.com

Groovy,
http://groovy.codehaus.org

Python
http://jython.org

Scala,
http://scala-lang.org

and
Ruby,
http://JRuby.org
Java and Scala are statically typed languages, whereas Groovy, Python, and Ruby are dynamically typed. Groovy is generally a superset of Java syntax, adding syntactic sugar and making type declarations and semicolon line endings to be generally optional. Jython is the Python interpreter on the JVM, supporting the same language as the original C-based interpreter, as well as the .NET-based interpreter called IronPython. Similarly, JRuby is the Ruby interpreter on the JVM, supporting the same language as the original C-based interpreter, as well as the .NET-based interpreter called IronRuby. Scala has strong support for both object oriented and functional programming styles, and although strongly typed, its use of type inference and other features support script-like coding. Groovy, Python, Ruby, and Scala are distributed with interactive console environments that aid learning and testing. Java and Scala create JVM-based applications with comparable performance, followed by JRuby, Groovy, and Jython (speed comparisons vary, however, as better language compilers are developed over time).
Any text editor may be used to code in these languages, as free, command-line compilers are included in their development kits. The Eclipse integrated development environment (IDE) has free plug-ins available for all these languages -- search for downloads on 
http://eclipse.org
The batch files buildJava.bat, buildGroovy.bat, buildPython.bat, buildRuby.bat, and buildScala.bat compile and run the source code in FruitBasket.java, FruitBasket.groovy, FruitBasket.py, FruitBasket.rb, and FruitBasket.scala, respectively. The appropriate bin subdirectories are assumed to be on the search path of the operating system. On Windows, for example, the standard installer places the Java home directory at a location like 
c:\program Files\Java\jdk1.6.0_21

Other JVM languages could be installed at directories like
C:\Groovy
C:\Jython
C:\JRuby
C:\Scala
To minimize the chance of interoperability problems, it may also be worth setting the following environment variables to appropriate installation directories: JAVA_HOME, GROOVY_HOME, JYTHON_HOME, JRUBY_HOME, and SCALA_HOME.
This distribution additionally illustrates one, free way of building an executable to launch a JVM application. There are console and Windows-mode versions of the otherwise, same executable: FruitBasketC.exe and FruitBasketW.exe. Note that these are not self-standing executables. They require a Java Runtime Environment (JRE) to be installed in a standard location. Code in .class and .jar files remains in those separate files rather than being bundled into the executable. There are commercial builders, packagers, and installers for JVM-based applications with many features. This simple approach is just a bit better than a batch file to run the JRE with a particular classpath, main class, and other runtime parameters. The pair of executables is built with a free program called exeJ, available from the following web page:
exeJ - Wraps the startup command line of your java application in an executable 
http://www.sureshotsoftware.com/exej/
exeJ is a command-line utility that takes a parameter indicating the configuration file to use for building the console and Windows executables, which are named 

using_java.exe

and
using_javaw.exe
which one would then rename to something befitting of the particular application. The Jython version of this fruit basket program was used to build the executables using the following command line: 
exej.exe -cfg FruitBasket.cfg
The configuration file assumes that the jython.jar package is installed in the directory 
C:\Jython
That file would typically be distributed with a JVM application coded in Jython. This fruit basket distribution includes the current exeJ package in the archive 
exej.zip
Source code to these fruit basket programs is pasted below, as well as in the separate FruitBasket.* files. A large collection of text tutorials on Java and other JVM languages is available at 
http://EmpowermentZone.com/java_doc.zip

Jamal

----------

/*
Content of FruitBasket.java
Fruit basket program in Java with SWT
Public domain by Jamal Mazrui
September 6, 2010
*/

import org.eclipse.swt.*;
import org.eclipse.swt.events.*;
import org.eclipse.swt.graphics.*;
import org.eclipse.swt.layout.*;
import org.eclipse.swt.widgets.*;

class FruitBasket {

public static void main(String[] args) {
Display display = new Display();
final Shell shell = new Shell(display);
shell.setText("Fruit Basket");

GridLayout lytGrid = new GridLayout();
lytGrid.numColumns = 3;
shell.setLayout(lytGrid);

Label lblFruit = new Label(shell, SWT.NONE);
lblFruit.setText("&Fruit:");

final Text txtFruit = new Text(shell, SWT.BORDER);

Button btnAdd = new Button(shell, SWT.PUSH);
btnAdd.setText("&Add");
shell.setDefaultButton(btnAdd);

Label lblBasket = new Label(shell, SWT.NONE);
lblBasket.setText("&Basket:");

final List lstBasket = new List(shell, SWT.BORDER | SWT.V_SCROLL);

Button btnDelete = new Button(shell, SWT.PUSH);
btnDelete.setText("&Delete");

btnAdd.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent e) {
String sFruit = txtFruit.getText().trim();
if (sFruit == "") {
ShowMessage(shell, "No fruit to add!", "Alert", SWT.OK);
}
else {
lstBasket.add(sFruit, 0);
lstBasket.select(0);
txtFruit.setText("");
}
txtFruit.setFocus();
}
});

btnDelete.addSelectionListener(new SelectionAdapter() {
public void widgetSelected(SelectionEvent e) {
int iIndex = lstBasket.getSelectionIndex();
if (iIndex == -1) {
ShowMessage(shell, "No fruit to delete!", "Alert", SWT.OK);
}
else {
lstBasket.remove(iIndex);
int iCount = lstBasket.getItemCount();
if (iIndex > iCount - 1) iIndex = iCount - 1;
lstBasket.select(iIndex);
}
lstBasket.setFocus();
}
});

shell.addShellListener(new ShellAdapter() {
public void shellClosed(ShellEvent e) {
if (ShowMessage(shell, "Exit program?", "Confirm", SWT.YES | SWT.NO | SWT.CANCEL) != SWT.YES) e.doit = false; 
}
});

shell.pack();
shell.open();
while(!shell.isDisposed()) {
if (!display.readAndDispatch()) display.sleep();
}
display.dispose();
} // main method
static int ShowMessage(Shell shell, String sMessage, String sText, int iStyle) { 
MessageBox mb = new MessageBox(shell, iStyle);
mb.setMessage(sMessage);
mb.setText(sText);
return mb.open();
} // showMessage method
} // FruitBasket class

----------

/*
Content of FruitBasket.groovy
Fruit basket program in Groovy with SWT
Public domain by Jamal Mazrui
September 6, 2010
*/

import org.eclipse.swt.*
import org.eclipse.swt.events.*
import org.eclipse.swt.graphics.*
import org.eclipse.swt.layout.*
import org.eclipse.swt.widgets.*

class FruitBasket {

static void main(args) {
def display = new Display()
def shell = new Shell(display)
shell.text = "Fruit Basket"

def lytGrid = new GridLayout()
lytGrid.numColumns = 3
shell.layout = lytGrid

def lblFruit = new Label(shell, SWT.NONE)
lblFruit.text = "&Fruit:"

def txtFruit = new Text(shell, SWT.BORDER)

def btnAdd = new Button(shell, SWT.PUSH)
btnAdd.text = "&Add"
shell.defaultButton = btnAdd

def lblBasket = new Label(shell, SWT.NONE)
lblBasket.text = "&Basket:"

def lstBasket = new List(shell, SWT.BORDER | SWT.V_SCROLL)

def btnDelete = new Button(shell, SWT.PUSH)
btnDelete.text = "&Delete"

btnAdd.addSelectionListener(new SelectionAdapter() {
void widgetSelected(SelectionEvent e) {
def sFruit = txtFruit.text.trim()
if(sFruit == "") {
ShowMessage(shell, "No fruit to add!", "Alert", SWT.OK)
}
else {
lstBasket.add(sFruit, 0)
lstBasket.select(0)
txtFruit.text = ""
}
txtFruit.setFocus()
}
})

btnDelete.addSelectionListener(new SelectionAdapter() {
void widgetSelected(SelectionEvent e) {
def iIndex = lstBasket.selectionIndex
if(iIndex == -1) {
ShowMessage(shell, "No fruit to delete!", "Alert", SWT.OK)
}
else {
lstBasket.remove(iIndex)
def iCount = lstBasket.itemCount
if(iIndex > iCount - 1) iIndex = iCount - 1
lstBasket.select(iIndex)
}
lstBasket.setFocus()
}
})

shell.addShellListener(new ShellAdapter() {
void shellClosed(ShellEvent e) {
if(ShowMessage(shell, "Exit program?", "Confirm", SWT.YES | SWT.NO | SWT.CANCEL) != SWT.YES) e.doit = false 
}
})

shell.pack()
shell.open()
while(!shell.isDisposed()) {
if(!display.readAndDispatch()) display.sleep()
}
display.dispose()
} // main method

static int ShowMessage(shell, sMessage, sText, iStyle) {
def mb = new MessageBox(shell, iStyle)
mb.message = sMessage
mb.text = sText
return mb.open()
} // showMessage method
} // FruitBasket class

----------

"""
Content of FruitBasket.py
Fruit basket program in Jython with SWT
Public domain by Jamal Mazrui
September 30, 2010
"""

from org.eclipse.swt import *
from org.eclipse.swt.events import *
from org.eclipse.swt.graphics import *
from org.eclipse.swt.layout import *
from org.eclipse.swt.widgets import *

def showMessage(shell, sMessage, sText, iStyle):
        mb = MessageBox(shell, iStyle, message=sMessage, text=sText)
        return mb.open()
# showMessage method

def addFruit(e):
        sFruit = txtFruit.text.strip()
        if not sFruit: showMessage(shell, 'No fruit to add!', 'Alert', SWT.OK)
        else:
                lstBasket.add(sFruit, 0)
                lstBasket.select(0)
                txtFruit.text = ''

        txtFruit.setFocus()
# addFruit method

def deleteFruit(e):
        iIndex = lstBasket.selectionIndex
        if iIndex == -1: showMessage(shell, 'No fruit to delete!', 'Alert', 
SWT.OK)
        else:
                lstBasket.remove(iIndex)
                iCount = lstBasket.itemCount
                if iIndex > iCount - 1: iIndex = iCount - 1
                lstBasket.select(iIndex)

        lstBasket.setFocus()
# deleteFruit method

def exitProgram(e):
if showMessage(shell, 'Exit program?', 'Confirm', SWT.YES | SWT.NO | SWT.CANCEL) != SWT.YES: e.doit = False 
# exitProgram method

display = Display()
shell = Shell(display, text='Fruit Basket', shellClosed=exitProgram)
lytGrid = GridLayout(numColumns=3)
shell.setLayout(lytGrid)

lblFruit = Label(shell, SWT.NONE, text='&Fruit:')
txtFruit = Text(shell, SWT.BORDER)
btnAdd = Button(shell, SWT.PUSH, text='&Add', widgetSelected=addFruit)
shell.defaultButton = btnAdd

lblBasket = Label(shell, SWT.NONE, text='&Basket:')
lstBasket = List(shell, SWT.BORDER | SWT.V_SCROLL)
btnDelete = Button(shell, SWT.PUSH, text='&Delete', widgetSelected=deleteFruit) 

shell.pack()
shell.open()

while not shell.isDisposed():
        if not display.readAndDispatch(): display.sleep()

display.dispose()

----------

/*
Content of FruitBasket.rb
Fruit basket program in JRuby with SWT
Public domain by Jamal Mazrui
September 6, 2010
*/

module FB
require 'java'
require 'swt.jar'
include_package 'org.eclipse.swt'
include_package 'org.eclipse.swt.events'
include_package 'org.eclipse.swt.graphics'
include_package 'org.eclipse.swt.layout'
include_package 'org.eclipse.swt.widgets'

def showMessage(shell, sMessage, sText, iStyle)
mb = MessageBox.new(shell, iStyle)
mb.message = sMessage
mb.text = sText
return mb.open
end # showMessage method
end # FB module

include FB
module FB
display = Display.new
shell = Shell.new(display)
shell.text = "Fruit Basket"
lytGrid = GridLayout.new
lytGrid.numColumns = 3
shell.layout = lytGrid

lblFruit = Label.new(shell, SWT::NONE)
lblFruit.text = "&Fruit:"

txtFruit = Text.new(shell, SWT::BORDER)

btnAdd = Button.new(shell, SWT::PUSH)
btnAdd.text = "&Add"
shell.defaultButton = btnAdd

lblBasket = Label.new(shell, SWT::NONE)
lblBasket.text = "&Basket:"

lstBasket = List.new(shell, SWT::BORDER | SWT::V_SCROLL)

btnDelete = Button.new(shell, SWT::PUSH)
btnDelete.text = "&Delete"

btnAdd.addSelectionListener do
sFruit = txtFruit.text.strip
if sFruit == ""
showMessage(shell, "No fruit to add!", "Alert", SWT::OK)
else
lstBasket.add(sFruit, 0)
lstBasket.select(0)
txtFruit.text = ""
end # if
txtFruit.setFocus
end # do

btnDelete.addSelectionListener do
iIndex = lstBasket.selectionIndex
if iIndex == -1
showMessage(shell, "No fruit to delete!", "Alert", SWT::OK)
else
lstBasket.remove(iIndex)
iCount = lstBasket.itemCount
iIndex = iCount - 1 if iIndex > iCount - 1
lstBasket.select(iIndex)
end # if
lstBasket.setFocus
end # do

class ClosedEvent < ShellAdapter
def initialize(shell)
@shell = shell
super()
end # initialize method

def shellClosed(e)
e.doit = false if showMessage(@shell, "Exit program?", "Confirm", SWT::YES | SWT::NO | SWT::CANCEL) != SWT::YES 
end # shellClosed methodd
end # ClosedEvent class

shell.addShellListener ClosedEvent.new(shell)

shell.pack
shell.open

display.sleep unless display.readAndDispatch while !shell.isDisposed
display.dispose
end # FB module

----------

/*
Content of FruitBasket.scala
Fruit basket program in Scala with SWT
Public domain by Jamal Mazrui
September 6, 2010
*/

import org.eclipse.swt._
import org.eclipse.swt.events._
import org.eclipse.swt.graphics._
import org.eclipse.swt.layout._
import org.eclipse.swt.widgets._

object FruitBasket extends Application {
val display = new Display()
val shell = new Shell(display)
shell.setText("Fruit Basket")

val lytGrid = new GridLayout()
lytGrid.numColumns = 3
shell.setLayout(lytGrid)

val lblFruit = new Label(shell, SWT.NONE)
lblFruit.setText("&Fruit:")

val txtFruit = new Text(shell, SWT.BORDER)

val btnAdd = new Button(shell, SWT.PUSH)
btnAdd.setText("&Add")
shell.setDefaultButton(btnAdd)

val lblBasket = new Label(shell, SWT.NONE)
lblBasket.setText("&Basket:")

val lstBasket = new List(shell, SWT.BORDER | SWT.V_SCROLL)

val btnDelete = new Button(shell, SWT.PUSH)
btnDelete.setText("&Delete")

btnAdd.addSelectionListener(new SelectionAdapter() {
override def widgetSelected(e: SelectionEvent) = {
val sFruit = txtFruit.getText().trim()
if(sFruit == "") {
ShowMessage(shell, "No fruit to add!", "Alert", SWT.OK)
}
else {
lstBasket.add(sFruit, 0)
lstBasket.select(0)
txtFruit.setText("")
}
txtFruit.setFocus()
}
})

btnDelete.addSelectionListener(new SelectionAdapter() {
override def widgetSelected(e: SelectionEvent) = {
var iIndex = lstBasket.getSelectionIndex()
if(iIndex == -1) {
ShowMessage(shell, "No fruit to delete!", "Alert", SWT.OK)
}
else {
lstBasket.remove(iIndex)
val iCount = lstBasket.getItemCount()
if(iIndex > iCount - 1) iIndex = iCount - 1
lstBasket.select(iIndex)
}
lstBasket.setFocus()
}
})

shell.addShellListener(new ShellAdapter() {
override def shellClosed(e: ShellEvent) = {
if(ShowMessage(shell, "Exit program?", "Confirm", SWT.YES | SWT.NO | SWT.CANCEL) != SWT.YES) e.doit = false 
}
})

shell.pack()
shell.open()
while(!shell.isDisposed()) {
if(!display.readAndDispatch()) display.sleep()
}
display.dispose()
def ShowMessage(shell: Shell, sMessage: String, sText : String, iStyle: Int): Int = { 
val mb = new MessageBox(shell, iStyle)
mb.setMessage(sMessage)
mb.setText(sText)
return mb.open
} // showMessage method
} // FruitBasket class


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