import java.util.TimeZone;
import javax.microedition.lcdui.Command;
import javax.microedition.lcdui.CommandListener;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.lcdui.Form;
import javax.microedition.lcdui.List;
import javax.microedition.midlet.MIDlet;
 
public class ConvertingTimeZones extends MIDlet implements CommandListener {
 
    private List list;
    private Form form;
    private Display display;
    private TimeZone timeZone;
    private Command backCommand;
    private Command exitCommand;
 
    /**
     * Constructor. Constructs the object and initializes buffer.
     */
    public ConvertingTimeZones() {
        timeZone = TimeZone.getDefault();
        backCommand = new Command("Back", Command.BACK, 1);
        exitCommand = new Command("Exit", Command.EXIT, 0);
 
        form = new Form("Time zone info");
        form.addCommand(backCommand);
        form.setCommandListener(this);
 
        //Create list filled with all available time zone IDs.
        list = new List("Select time zone:", List.IMPLICIT, 
                        timeZone.getAvailableIDs(), null);
        list.addCommand(exitCommand);
        list.setCommandListener(this);
 
        display = Display.getDisplay(this);
        display.setCurrent(list);
    }
 
    /**
     * From CommandListener.
     * Called by the system to indicate that a command has been invoked on a
     * particular displayable.
     * @param cmd the command that was invoked
     * @param displayable the displayable where the command was invoked
     */
    public void commandAction(Command cmd, Displayable displayable) {
        if (cmd == List.SELECT_COMMAND) {
            //Clear form.
            form.deleteAll();
            //Get selected time zone index.
            String timeZoneID = list.getString(list.getSelectedIndex());
            form.append("Time zone ID: " + timeZoneID + "\n");
            form.append("Time offset: ");
            //Display the GMT offset for selected time zone in hours.
            form.append(String.valueOf(
                   timeZone.getTimeZone(timeZoneID).getRawOffset() / 3600000));
            form.append(" hours");
 
            display.setCurrent(form);
        } else if (cmd == backCommand) {
            display.setCurrent(list);
        } else if (cmd == exitCommand) {
            notifyDestroyed();
        }
    }
 
    /**
     * From MIDlet.
     * Called when the MIDlet is started.
     */
    public void startApp() {
        // No implementation required.
    }
 
    /**
     * From MIDlet.
     * Called to signal the MIDlet to enter the Paused state.
     */
    public void pauseApp() {
        // No implementation required.
    }
 
    /**
     * From MIDlet.
     * Called to signal the MIDlet to terminate.
     * @param unconditional whether the MIDlet has to be unconditionally
     * terminated
     */
    public void destroyApp(boolean unconditional) {
    }
}