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Code:



 

package ora.ch4;



import java.io.IOException;

import java.util.Calendar;

import java.util.Date;

import javax.microedition.lcdui.Alert;

import javax.microedition.lcdui.AlertType;

import javax.microedition.lcdui.Choice;

import javax.microedition.lcdui.ChoiceGroup;

import javax.microedition.lcdui.Command;

import javax.microedition.lcdui.CommandListener;

import javax.microedition.lcdui.DateField;

import javax.microedition.lcdui.Display;

import javax.microedition.lcdui.Displayable;

import javax.microedition.lcdui.Form;

import javax.microedition.lcdui.Gauge;

import javax.microedition.lcdui.Image;

import javax.microedition.lcdui.ImageItem;

import javax.microedition.lcdui.Item;

import javax.microedition.lcdui.ItemStateListener;

import javax.microedition.lcdui.List;

import javax.microedition.lcdui.Screen;

import javax.microedition.lcdui.StringItem;

import javax.microedition.lcdui.TextField;

import javax.microedition.midlet.MIDlet;



public class ItemMIDlet extends MIDlet

        implements CommandListener, ItemStateListener {



    // The MIDlet's Display object

    private Display display;



    // Flag indicating first call of startApp

    protected boolean started;



    // Exit command

    private Command exitCommand;



    // Back to examples list command

    private Command backCommand;



    // The example selection list

    private List examplesList;



    // The Screens used to demonstrate different Items

    private Screen[] screens;



    // The example names. Used to populate the list.

    private String[] examples = {

        "StringItem", "TextField", "DateField",

        "ImageItem", "Gauge", "ChoiceGroup",

        "List", "Alert", "Sounds"

    };



    // List of alert types

    private AlertType[] alertTypes = new AlertType[] {

        AlertType.ALARM, AlertType.CONFIRMATION, AlertType.ERROR,

        AlertType.INFO, AlertType.WARNING, null

    };



    private String[] alertTypeNames = new String[] {

        "ALARM", "CONFIRMATION", "ERROR", "INFO", "WARNING", "None"

    };



    protected void startApp() {

        if (!started) {

            started = true;

            display = Display.getDisplay(this);



            // Create the common commands

            createCommands();



            // Create the screens

            createScreens();



            // Create the list of examples

            createList();



            // Start with the List

            display.setCurrent(examplesList);

        }

    }



    protected void pauseApp() {

    }



    protected void destroyApp(boolean unconditional) {

    }



    public void commandAction(Command c, Displayable d) {

        if (d == examplesList) {

            // New example selected

            int index = examplesList.getSelectedIndex();

            display.setCurrent(screens[index]);

        } else if (c == exitCommand) {

            // Exit. No need to call destroyApp

            // because it is empty.

            notifyDestroyed();

        } else if (c == backCommand) {

            // Go back to main selection list

            display.setCurrent(examplesList);

        } else if (c == List.SELECT_COMMAND) {

            // Selection made in the IMPLICIT LIST

            handleChoiceSelection((Choice)d);

        }

    }



    public void itemStateChanged(Item item) {

        if (item instanceof TextField) {

            System.out.println("Text field content: <" +

                            ((TextField)item).getString() + ">");

        } else if (item instanceof DateField) {

            DateField df = (DateField)item;

            Date date = df.getDate();

            if (date != null) {

                Calendar cal = Calendar.getInstance();

                cal.setTime(date);

                System.out.println("Date field content set to " + date);

            } else {

                System.out.println("Date field content set to null");

            }

        } else if (item instanceof Gauge) {

            int value = ((Gauge)item).getValue();

            System.out.println("Gauge value set to " + value);

        } else if (item instanceof ChoiceGroup) {

            handleChoiceSelection((Choice)item);

        } else {

            System.out.println("Item state changed in " + item);

        }

    }



    private void createCommands() {

        exitCommand = new Command("Exit", Command.EXIT, 0);

        backCommand = new Command("Back", Command.BACK, 1);

    }



    private void createList() {

        examplesList = new List("Select Example", List.IMPLICIT);

        for (int i = 0; i < examples.length; i++) {

            examplesList.append(examples[i], null);

        }

        examplesList.setCommandListener(this);

    }



    private void createScreens() {

        screens = new Screen[examples.length];

        screens[0] = createStringsForm();

        screens[1] = createTextFieldForm();

        screens[2] = createDateFieldForm();

        screens[3] = createImageItemForm();

        screens[4] = createGaugeForm();

        screens[5] = createChoiceGroupForm();

        screens[6] = createListExample();

        screens[7] = createAlertForm();

        screens[8] = createSoundsForm();

    }



    private void addCommands(Displayable d) {

        d.addCommand(exitCommand);

        d.addCommand(backCommand);

        d.setCommandListener(this);

        if (d instanceof Form) {

            ((Form)d).setItemStateListener(this);

        }

    }



    // Example for StringItem

    private Form createStringsForm() {

        Form form = new Form("StringItem");



        form.append(new StringItem("State ", "OK"));

        form.append(new StringItem(null, "No label\n"));

        form.append(new StringItem(null, "Line\nbreak"));

        form.append(new StringItem("Label", "Text."));

        form.append(new StringItem("Label2 ", "Text2."));



        addCommands(form);

        return form;

    }



    // Example for TextField

    private Form createTextFieldForm() {

        Form form = new Form("TextField");



        form.append(new TextField("Any", null, 8, TextField.ANY));

        form.append(new TextField("Phone", "1234567890", 10, TextField.PHONENUMBER));

        form.append(new TextField("Number", "12345", 8, TextField.NUMERIC));

        form.append(new TextField("Password", null, 8, TextField.PASSWORD | TextField.NUMERIC));



        addCommands(form);

        return form;

    }



    // Example for DateField

    private Form createDateFieldForm() {

        Form form = new Form("DateField");



        // Get Calendar for the epoch date and time

        Calendar baseCal = Calendar.getInstance();

        Date baseDate = new Date(0);

        baseCal.setTime(baseDate);



        // Get Calendar for now and use the epoch

        // values to reset the date to the epoch.

        Calendar cal = Calendar.getInstance();

        Date now = new Date();

        cal.setTime(now);

        cal.set(Calendar.YEAR, baseCal.get(Calendar.YEAR));

        cal.set(Calendar.MONTH, baseCal.get(Calendar.MONTH));

        cal.set(Calendar.DATE, baseCal.get(Calendar.DATE));



        DateField timeOnly = new DateField("Time", DateField.TIME);

        DateField dateOnly = new DateField("Date", DateField.DATE);

        DateField both = new DateField("Both", DateField.DATE_TIME);



        timeOnly.setDate(cal.getTime());

        dateOnly.setDate(now);

        both.setDate(now);



        form.append(timeOnly);

        form.append(dateOnly);

        form.append(both);



        addCommands(form);

        return form;

    }



    // Example for ImageItem

    private Form createImageItemForm() {

        Form form = new Form("ImageItem");



        try {

            Image red = Image.createImage("/ora/ch4/resources/red.png");

            Image blue = Image.createImage("/ora/ch4/resources/blue.png");



            // ImageItems with labels

            // (1)

            form.append(new ImageItem("Center", red, ImageItem.LAYOUT_CENTER, null));



            // (2)

            form.append(new ImageItem("Left", red, ImageItem.LAYOUT_LEFT, null));



            // (3)

            form.append(new ImageItem("Right", red, ImageItem.LAYOUT_RIGHT, null));



            // (4)

            form.append(new ImageItem("Default", red, ImageItem.LAYOUT_DEFAULT, null));



            // ImageItems with no labels

            // (5)

            form.append(new ImageItem(null, blue,

                    ImageItem.LAYOUT_NEWLINE_BEFORE |

                    ImageItem.LAYOUT_CENTER |

                    ImageItem.LAYOUT_NEWLINE_AFTER, null));



            // (6)

            form.append(new ImageItem(null, blue,

                    ImageItem.LAYOUT_NEWLINE_BEFORE |

                    ImageItem.LAYOUT_DEFAULT |

                    ImageItem.LAYOUT_NEWLINE_AFTER, null));



            // (7)

            form.append(new ImageItem(null, blue,

                    ImageItem.LAYOUT_NEWLINE_BEFORE |

                    ImageItem.LAYOUT_RIGHT |

                    ImageItem.LAYOUT_NEWLINE_AFTER, null));



            // (8)

            form.append(new ImageItem(null, blue, ImageItem.LAYOUT_DEFAULT, null));

            form.append(new ImageItem(null, blue, ImageItem.LAYOUT_DEFAULT, null));

        } catch (IOException ex) {

            form.append("Failed to load images");

        }



        addCommands(form);

        return form;

    }



    // Example for Gauge

    private Form createGaugeForm() {

        Form form = new Form("Gauge");



        form.append(new Gauge(null, true, 100, 50));

        form.append(new Gauge(null, true, 100, 25));

        form.append(new Gauge(null, false, 100, 50));



        addCommands(form);

        return form;

    }



    // Example for ChoiceGroup

    private Form createChoiceGroupForm() {

        Form form = new Form("ChoiceGroup");



        try {

            Image red = Image.createImage("/ora/ch4/resources/red.png");

            Image green = Image.createImage("/ora/ch4/resources/green.png");

            Image blue = Image.createImage("/ora/ch4/resources/blue.png");



            // Exclusive choice group

            String[] strings = new String[] { "Red", "Green", "Blue" };

            Image[] images = new Image[] { red, green, blue };

            ChoiceGroup exGroup = new ChoiceGroup("Choose one", ChoiceGroup.EXCLUSIVE,

                                                        strings, images);

            form.append(exGroup);



            // Multiple choice group

            ChoiceGroup multiGroup = new ChoiceGroup("Choose any", ChoiceGroup.MULTIPLE);

            form.append(multiGroup);

            multiGroup.append("Use SSL", null);

            multiGroup.append("Reconnect on failure", null);

            multiGroup.append("Enable tracing", null);

        } catch (IOException ex) {

            form.append("Failed to load images");

        }



        addCommands(form);

        return form;

    }



    // Example for List

    private Screen createListExample() {

        List list = new List("List", List.IMPLICIT);



        try {

            Image red = Image.createImage("/ora/ch4/resources/red.png");

            Image green = Image.createImage("/ora/ch4/resources/green.png");

            Image blue = Image.createImage("/ora/ch4/resources/blue.png");



            list.append("Red", red);

            list.append("Green", green);

            list.append("Blue", blue);

        } catch (IOException ex) {

            Form form = new Form("Error");

            form.append("Failed to load images");

            return form;

        }



        addCommands(list);

        return list;

    }



    // Example for Alert

    private Screen createAlertForm() {

        final Form form = new Form("Alert");



        // A ChoiceGroup that allows the user to choose between

        // a modal Alert or an Alert with a finite timeout.

        final ChoiceGroup limitGroup = new ChoiceGroup("Timeout", Choice.EXCLUSIVE);

        limitGroup.append("Forever", null);

        limitGroup.append("Bounded 5s", null);

        form.append(limitGroup);



        // A Gauge that allows the user to choose the

        // timeout for the Alert. This appears only if

        // the "Bounded" option is selected.

        final Gauge gauge = new Gauge(null, true, 30, 5);



        // A ChoiceGroup that lets the user pick the

        // type of Alert

        final ChoiceGroup group = createAlertChoiceGroup(true);

        form.append(group);



        // A Command that is used to display the Alert

        final Command okCommand = new Command("OK", Command.OK, 0);



        // Add CommandListener for back/exit commands

        // and the OK command, which is specific to this Form

        form.addCommand(okCommand);

        form.addCommand(exitCommand);

        form.addCommand(backCommand);

        form.setCommandListener(new CommandListener() {

            public void commandAction(Command c, Displayable d) {

                if (c == okCommand) {

                    // Create and display the Alert



                    // Get the alert type from the

                    // second ChoiceGroup

                    int selectedType = group.getSelectedIndex();

                    AlertType alertType = alertTypes[selectedType];

                    String name = alertTypeNames[selectedType];



                    // Get the timeout. This is FOREVER if the

                    // first item in the first ChoiceGroup is

                    // selected. Otherwise it is the value in

                    // the Gauge

                    int timeout = Alert.FOREVER;

                    String timeoutString = "none";

                    if (limitGroup.isSelected(1)) {

                        // "Bounded" selected - get the timeout.

                        timeout = gauge.getValue() * 1000;

                        timeoutString = gauge.getValue() + "s";

                    }



                    // Create the Alert and set the timeout

                    Alert alert = new Alert("Alert!",

                        "Alert type: " + name + "\nTimeout = " + timeoutString,

                        null, alertType);

                    alert.setTimeout(timeout);



                    // Display the Alert.

                    display.setCurrent(alert);

                } else {

                    // Delegate others to the usual commandAction

                    ItemMIDlet.this.commandAction(c, d);

                }

            }

        });



        // Set our own ItemStateListener

        form.setItemStateListener(new ItemStateListener() {

            public void itemStateChanged(Item item) {

                if (item == limitGroup) {

                    if (limitGroup.getSelectedIndex() == 0) {

                        // Get rid of the Gauge

                        form.delete(1);

                    } else {

                        // Add the Gauge

                        form.insert(1, gauge);

                    }

                } else if (item == gauge) {

                    int value = gauge.getValue();

                    limitGroup.set(1, "Bounded " + value + "s", null);

                }

            }

        });

        return form;

    }





    // Example for Sounds

    private Screen createSoundsForm() {

        final Form form = new Form("Sounds");



        // A ChoiceGroup that lets the user pick the

        // type of sound

        final ChoiceGroup group = createAlertChoiceGroup(false);

        form.append(group);



        addCommands(form);



        // Set our own ItemStateListener

        form.setItemStateListener(new ItemStateListener() {

            public void itemStateChanged(Item item) {

                // Get the alert type from the ChoiceGroup

                int selectedType = group.getSelectedIndex();

                AlertType alertType = alertTypes[selectedType];

                boolean result = alertType.playSound(display);

                System.out.println("A sound was " + (result ? "" : "not ")

                                    + "played.");



            }

        });

        return form;

    }



    // Handles the selection for a Choice

    private void handleChoiceSelection(Choice choice) {

        int count = choice.size();

        boolean[] states = new boolean[count];

        int selCount = choice.getSelectedFlags(states);

        if (selCount > 0) {

            System.out.println("Selected items:");

            for (int i = 0; i < count; i++) {

                if (states[i]) {

                    System.out.println("\t" + choice.getString(i));

                }

            }

        } else {

            System.out.println("No selected items.");

        }

        int selectedIndex = choice.getSelectedIndex();

        System.out.println("Selected index is " + selectedIndex);

    }



    // Creates a ChoiceGroup containing a set of Alert types

    private ChoiceGroup createAlertChoiceGroup(boolean includeNone) {

        ChoiceGroup group = new ChoiceGroup("Alert Type", Choice.EXCLUSIVE);

        int count = includeNone ? alertTypeNames.length : alertTypeNames.length - 1;

        for (int i = 0; i < count; i++) {

            group.append(alertTypeNames[i], null);

        }

        return group;

    }

}



J2ME in a Nutshell

By Kim Topley

First Edition March 2002

Series: In a Nutshell

ISBN: 0-596-00253-X