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A P P E N D I X  A
Sample Application Source Code

This appendix provides the source code for the four files that comprise the sample ConverterMIDlet application:

ConverterMIDlet Source Code

CODE EXAMPLE A-1 ConverterMIDlet.java 
package myconverter;

 

import javax.microedition.midlet.*;

import javax.microedition.lcdui.*;

import javax.microedition.rms.*;

 

public class ConverterMIDlet extends MIDlet {

  static  ConverterMIDlet instance;

  private Converter       mainScreen;

 

  private static String storedDataStr = "FromToCurr";

  private RecordStore   storedData;

  

  /**Construct the midlet*/

  public ConverterMIDlet() {

    this.instance = this;

    try {

      jbInit();

    }

    catch(Exception e) {

      e.printStackTrace();

    }

  }

 

  /**Main method*/

  public void startApp() {

    int fridx = 0;

    int toidx = 1;

    try {

      storedData = RecordStore.openRecordStore(storedDataStr, true);

      if (storedData.getNumRecords() > 0) {

        byte[] data = storedData.getRecord(1);

        fridx = (int)data[0];

        toidx = (int)data[1];

      }

    } catch (RecordStoreException e) {

    }

    mainScreen = new Converter(fridx, toidx);

    Display.getDisplay(this).setCurrent(mainScreen);

  }

 

  /**Handle pausing the MIDlet*/

  public void pauseApp() {

  }

 

  /**Handle destroying the MIDlet*/

  public void destroyApp(boolean unconditional) {

    try {

      byte[] data = new byte[2];

      data[0] = (byte)mainScreen.settings.frList.getSelectedIndex();

      data[1] = (byte)mainScreen.settings.toList.getSelectedIndex();

      if (storedData.getNumRecords() > 0)

        storedData.setRecord(1, data, 0, 2);

      else

        storedData.addRecord(data, 0, 2);

    } catch (Exception e) {

    }

  }

 

  /**Quit the MIDlet*/

  public static void quitApp() {

    instance.destroyApp(true);

    instance.notifyDestroyed();

    instance = null;

  }

  public static void setScreen(Displayable d) {

    Display.getDisplay(instance).setCurrent(d);

  }

 

  private void jbInit() throws Exception {

  }

}

Converter Source Code

CODE EXAMPLE A-2 Converter.java 
package converter;

 

import javax.microedition.lcdui.*;

 

public class Converter extends Form {

  static Converter  instance = null;

  TextField  frTextField = new TextField("", "", 1, 1);

  StringItem toStringItem = new StringItem("", "");

 

  Settings  settings  = null;

 

  /**Construct the displayable*/

  public Converter(int initFr, int initTo) {

    super("Converter");

    // set up this Displayable to listen to command events

    setCommandListener(new CommandListener()  {

      public void commandAction(Command c, Displayable d) {

        this_commandPerformed(c, d);

      }

    });

    setItemStateListener(new ItemStateListener() {

      public void itemStateChanged(Item item) {

        int fridx = settings.frList.getSelectedIndex();

        int toidx = settings.toList.getSelectedIndex();

        convert(fridx, toidx);

      }

    });

    try {

      jbInit();

    }

    catch(Exception e) {

      e.printStackTrace();

    }

    instance = this;

    settings = new Settings(initFr, initTo);

    changeFrom(initFr);

    changeTo(initTo);

  }

 

  /**Component initialization*/

  private void jbInit() throws Exception  {

    toStringItem.setLabel("(to)");

    frTextField.setLabel("(from)");

    frTextField.setConstraints(TextField.NUMERIC);

    frTextField.setMaxSize(10);

    // add the Exit command

    addCommand(new Command("Exit", Command.EXIT, 1));

    addCommand(new Command("Settings", Command.SCREEN, 1));

    this.append(frTextField);

    this.append(toStringItem);

  }

 

  /**Handle command events*/

  public void this_commandPerformed(Command c, Displayable d) {

    if (c.getCommandType() == Command.EXIT) {

      // exit the MIDlet

      ConverterMIDlet.quitApp();

    } else {

      ConverterMIDlet.setScreen(settings);

    }

  }

  public static void goBack(int fridx, int toidx) {

    instance.convert(fridx, toidx);

    ConverterMIDlet.setScreen(instance);

  }

 

  void convert(int fridx, int toidx) {

    String frvstr = frTextField.getString();

    int toval = 0;

    if (frvstr.length() > 0) {

      toval = Currencies.convert(

Integer.parseInt(frvstr), fridx, toidx);

    }

    toStringItem.setText(String.valueOf(toval));

  }

  static void changeFrom(int newidx) {

    instance.frTextField.setLabel(Currencies.currencies[newidx]);

  }

  static void changeTo(int newidx) {

    instance.toStringItem.setLabel(Currencies.currencies[newidx]);

  }

}

Currencies Source Code

CODE EXAMPLE A-3 Currencies.java 
package converter;

 

import javax.microedition.lcdui.*;

 

public class Currencies extends List {

  static String[] currencies = {

    new String("US $"),      // US dollar

    new String("JP \u00a5"), // yen

    new String("Euro")

  };

  static int[][] ratesTop = {

    {  100, 13315,   112},

    {  100,   100,   100},

    {  100, 11830,   100}

  };

  static int[][] ratesBot = {

    {  100,   100,   100},

    {13315,   100, 11830},

    {  112,   100,   100}

  };

  static int  TYPE_FROM  = 0,

              TYPE_TO   = 1;

  private int type;

 

  /**Construct the displayable*/

  public Currencies(String name, int type, int initidx) {

    super(name + "Currencies", List.EXCLUSIVE);

    // set up this Displayable to listen to command events

    setCommandListener(new CommandListener()  {

      public void commandAction(Command c, Displayable d) {

        this_commandPerformed(c, d);

      }

    });

    try {

      jbInit();

    }

    catch(Exception e) {

      e.printStackTrace();

    }

    this.type = type;

    setSelectedIndex(initidx, true);

  }

 

  /**Component initialization*/

  private void jbInit() throws Exception  {

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

      this.append(currencies[i], null);

    }

    //addCommand(new Command("Back", Command.BACK, 2));

    addCommand(new Command("Save", Command.OK,   1));

  }

 

  /** Handle command events*/

  public void this_commandPerformed(Command c, Displayable d) {

    // add your command event handling here

    if (c.getCommandType() == Command.OK) {

      // save the settings and update the mainScreen

      if (type == TYPE_FROM)

        Converter.changeFrom(getSelectedIndex());

      else

        Converter.changeTo(getSelectedIndex());

    }

    // always goes back to Settings Screen

    Settings.goBack();

  }

 

  public static int convert(int frval, int fridx, int toidx) {

    return (frval * ratesTop[fridx][toidx]) / ratesBot[fridx][toidx];

  }

}

Settings Source Code

CODE EXAMPLE A-4 Settings.java 
package converter;

 

import javax.microedition.lcdui.*;

 

public class Settings extends List {

  private static Settings instance = null;

  Currencies frList = null;

  Currencies toList = null;

 

  /**Construct the displayable*/

  public Settings(int initFr, int initTo) {

    super("Settings", List.IMPLICIT);

    // set up this Displayable to listen to command events

    setCommandListener(new CommandListener()  {

      public void commandAction(Command c, Displayable d) {

        this_commandPerformed(c, d);

      }

    });

    try {

      jbInit();

    }

    catch(Exception e) {

      e.printStackTrace();

    }

    instance = this;

    frList = new Currencies("From", Currencies.TYPE_FROM, initFr);

    toList = new Currencies("To",   Currencies.TYPE_TO,   initTo);

  }

 

  /**Component initialization*/

  private void jbInit() throws Exception  {

    append("1. From Currencies", null);

    append("2. To Currencies", null);

    addCommand(new Command("Back", Command.BACK, 2));

  }

 

  /** Handle command events*/

  public void this_commandPerformed(Command c, Displayable d) {

    // add your command event handling here

    if (c.getCommandType() == Command.BACK) {

      Converter.goBack(frList.getSelectedIndex(), toList.getSelectedIndex());

    } else {

        if (getSelectedIndex() == 0)

            ConverterMIDlet.setScreen(frList);

        else

            ConverterMIDlet.setScreen(toList);

    }

  }

 

  public static void goBack() {

    ConverterMIDlet.setScreen(instance);

  }

}

 



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