gistfile1.txt

import javax.microedition.lcdui.*;
import javax.microedition.midlet.*;
import javax.microedition.rms.*;

public class ConversorMonedasJavaME extends MIDlet implements CommandListener {
  private Display display;

  private Form form;
  private ChoiceGroup lista;
  private TextField cantidad;

  private Command salirCommand;
  private Command convertirCommand;
  private String name;

  public ConversorMonedasJavaME() {
    name = "Conversor de Moneda";

    display = Display.getDisplay(this);

    // un item para preguntar que tipo del grupo se escoger para el alert
    lista = new ChoiceGroup("Elije la moneda de origen:", ChoiceGroup.EXCLUSIVE);
    lista.append("$", null);
    lista.append("CAD", null);
    lista.append("CHF", null);
    lista.append("Libra", null);
    lista.append("PST", null);
    lista.append("Yen", null);
    lista.setSelectedIndex(0, true);

    cantidad = new TextField("Introduce la cantidad", "", 100, TextField.DECIMAL);

    form = new Form(name);
    form.append(lista);
    form.append(cantidad);

    convertirCommand = new Command("Convertir", Command.OK, 0);
    salirCommand = new Command("Salir", Command.EXIT, 3);
    volverCommand = new Command("Volver", Command.BACK, 4);

    form.addCommand(convertir);
    form.addCommand(salir);
    form.setCommandListener(this);
  }

	protected void startApp() {
		display.setCurrent(form);
	}

  public void pauseApp() {
  }

  public void destroyApp(boolean unconditional) {
  }

  public double factorForIndex(int index) {
    switch(index) {
      case 0: return 1.18;
      case 1: return 1.5;
      case 2: return 1.16;
      case 3: return 0.89;
      case 4: return 166.386;
      case 5: return 131.95;
    }
    return 0;
  }

  public String nameForIndex(int index) {
    switch(index) {
      case 0: return "USD";
      case 1: return "CAD";
      case 2: return "CHF";
      case 3: return "GBP";
      case 4: return "PTS";
      case 5: return "JPY";
    }
    return "";
  }

	public void commandAction(Command c, Displayable d) {
		// Miramos si salimos o mostramos la alerta
		if (c == salirCommand) {
			destroyApp(true);
      notifyDestroyed();

    } else if (c == volverCommand) {
      display.setCurrent(form);

		} else if (c == convertirCommand) {
      int index = lista.getSelectedIndex();
      double factor = factorForIndex(index);
      String name = nameForIndex(index);
      double original = Double.parseDouble(cantidad.getString());
      double result = original * factor;
      String message = String.format("$.2f %s = %.10f €", original, name, result);


      Screen screen = new Screen();
      screen.setTitle(name);
      screen.append(message);

      screen.addCommand(salir);
      screen.addCommand(volverCommand);

      display.setCurrent(screen);
    }
	}

}