Ch04 code

package com.scmadkit.ch04;
 
import javax.microedition.midlet.MIDlet;
import javax.microedition.midlet.MIDletStateChangeException;
 
public class HelloWorldMIDlet extends MIDlet {
   protected void startApp()                                   
      throws MIDletStateChangeException {                      
         System.out.println("Hello world!");                   
   }                                                            
 
   protected void pauseApp() {                                 
      System.out.println("Hold on for a second, world!");      
   }                                                           
 
   protected void destroyApp(boolean unconditional)            
      throws MIDletStateChangeException {                      
         System.out.println("Good Bye world!");                
   }                                                           
}

package com.scmadkit.ch04;
 
import javax.microedition.lcdui.*;
 
/**
 * This is the main screen for the application. This screen simply provides some
 * information about the current status of the application.
 * 
 * @author Sathya.Srinivasan
 */
public class MainScreen extends TextBox {
	/** Command to set the alarm */
	public static final Command SET_ALARM_COMMAND = new Command("Set alarm",
			Command.SCREEN, 1);
 
	/** Command to stop the application */
	public static final Command EXIT_COMMAND = new Command("Exit",
			Command.EXIT, 2);
 
	private static final String MESSAGE = "Set alarm by selecting the \"Set Alarm\" command.";
 
	/**
	 * Creates a new instance of MainScreen.
	 */
	public MainScreen() {
		super("Main Screen", MESSAGE, 100, TextField.ANY);
		this.initialize();
	}
 
	/**
	 * Initializes this screen with necessary UI objects.
	 */
	private void initialize() {
		this.addCommand(SET_ALARM_COMMAND);
		this.addCommand(EXIT_COMMAND);
	}
}

package com.scmadkit.ch04;
 
import java.util.Calendar;
import java.util.Date;
import javax.microedition.lcdui.*;
 
/**
 * This screen is used to take user input regarding the time when the alarm
 * should be set.
 * 
 * @author Sathya.Srinivasan
 */
public class AlarmSetForm extends Form implements TimeDisplay {
	/** Command to set the time */
	public static final Command OK_COMMAND = new Command("OK", Command.OK, 1);
 
	/** Command to go back to the main screen */
	public static final Command CANCEL_COMMAND = new Command("Cancel",
			Command.CANCEL, 2);
 
	private DateField dateField = new DateField("Date", DateField.TIME);
 
	private StringItem stringItem = new StringItem("Current Time", new Date()
			.toString());
 
	/**
	 * Creates a new instance of AlarmSetForm.
	 */
	public AlarmSetForm() {
		super("Alarm Details");
		this.initialize();
	}
 
	/**
	 * Initializes this screen with necessary UI objects.
	 */
	private void initialize() {
		// Add UI Objects.
		this.append(dateField);
		this.append(stringItem);
 
		// Add Commands to this screen.
		this.addCommand(OK_COMMAND);
		this.addCommand(CANCEL_COMMAND);
	}
 
	/**
	 * Gets the time that was set by the user.
	 */
	public Date getAlarmTime() {
		// Get the time set by the user.
		Date dateValue = dateField.getDate();
 
		// If no time has been set by user, return null.
		if (dateValue == null) {
			return null;
		}
 
		Calendar cal = Calendar.getInstance();
		Calendar ref = Calendar.getInstance();
		cal.setTime(dateValue);
		cal.set(Calendar.MONTH, ref.get(Calendar.MONTH));
		cal.set(Calendar.YEAR, ref.get(Calendar.YEAR));
		cal.set(Calendar.DAY_OF_MONTH, ref.get(Calendar.DAY_OF_MONTH));
		return cal.getTime();
	}
 
	/**
	 * Sets the current time.
	 * 
	 * @param time The current time.
	 */
	public void setTime(Date time) {
		stringItem.setText(time.toString());
	}
}

package com.scmadkit.ch04;
 
import javax.microedition.lcdui.*;
 
/**
 * This screen is displayed when the alarm occurs.
 * 
 * @author Sathya.Srinivasan
 */
public class AlarmForm extends TextBox {
 
	public static final Command OK_COMMAND = new Command("Dismiss", Command.OK,
			1);
 
	/** Creates a new instance of AlarmForm */
	public AlarmForm() {
		super("ALARM!", "*BEEP* *BEEP* *BEEP*", 100, TextField.ANY);
		this.initialize();
	}
 
	/**
	 * Initializes the UI objects of this screen.
	 */
	private void initialize() {
		this.addCommand(OK_COMMAND);
	}
}

package com.scmadkit.ch04;
 
import java.util.TimerTask;
import javax.microedition.lcdui.Display;
import javax.microedition.lcdui.Displayable;
import javax.microedition.midlet.MIDlet;
 
/**
 * This is a customization of the TimerTask class to show the alarm screen at
 * the scheduled time.
 * 
 * @author Sathya.Srinivasan
 */
public class AlarmTask extends TimerTask {
 
	private Displayable dis;
	private MIDlet midlet;
 
	/**
	 * Sets the screen that should be displayed when the scheduled event occurs.
	 * 
	 */
	public void setDisplayable(MIDlet midlet, Displayable dis) {
		this.dis = dis;
		this.midlet = midlet;
	}
 
	public void run() {
		Display.getDisplay(midlet).setCurrent(dis);
	}
}

package com.scmadkit.ch04;
 
import java.util.Date;
import java.util.TimerTask;
 
/**
 * This task acts like a clock. The task itself simply changes the
 * contents of the associated display with the current date.
 *
 * @author Sathya.Srinivasan
 */
public class ClockTask extends TimerTask {
 
   private TimeDisplay display;
 
   /** Creates a new instance of ClockTask */
   public ClockTask(TimeDisplay display) {
      this.display = display;
   }
 
   public void run() {                                            
      display.setTime(new Date());                                
   }                                                              
}

package com.scmadkit.ch04;
 
import java.util.Date;
 
/**
 * Interface to an UI that sets the current time.
 * 
 * @author Sathya.Srinivasan
 */
public interface TimeDisplay {
	/**
	 * Sets the current time on the display.
	 * 
	 * @param time The current time.
	 */
	public void setTime(Date time);
}

package com.scmadkit.ch04;
 
import java.util.Date;
import java.util.Timer;
import javax.microedition.midlet.*;
import javax.microedition.lcdui.*;
 
/**
 * This is the main class that defines
 * the lifecycle of the application.
 * The AMS will call the startApp() method
 * when this application is launched.
 *
 * @author Sathya.Srinivasan
*/
public class AlarmMIDlet extends MIDlet implements CommandListener {
   private AlarmSetForm alarmSetForm = new AlarmSetForm();
   private AlarmForm alarmForm = new AlarmForm();
   private MainScreen mainForm = new MainScreen();
   private Timer timer = new Timer();
   private AlarmTask task;
   private ClockTask clock;
   private Timer clockTimer = new Timer();
 
   /**
    * Starts this application.
    */
   public void startApp() {
      // Adds this class as a listener to commands in various screens.
      mainForm.setCommandListener(this);
      alarmSetForm.setCommandListener(this);
      alarmForm.setCommandListener(this);
 
      // Sets the clock timer.
      clock = new ClockTask(alarmSetForm);
      clockTimer.scheduleAtFixedRate(clock, 1000, 1000);
 
      // Shows the main screen.
      Display.getDisplay(this).setCurrent(mainForm);
   }
 
   /**
    * Pauses this application. We don't have to do much here for this 
    * example.
    */
   public void pauseApp() {
   }
 
   /**
    * This method is called when the application is destroyed by the 
    * AMS. If a Timer has been set, we might want to cancel it before 
    * closing the app.
    */
   public void destroyApp(boolean unconditional) {
      // Cancels any tasks in the timer.
      timer.cancel();
   }
 
   /**
    * This method is invoked whenever a command is executed by the 
    * user, as this class has registered itself as a listener to all 
    * the screens.
    */
   public void commandAction(Command c, Displayable d) {
      if(c == AlarmSetForm.OK_COMMAND) {
         mainForm.setString("Alarm has been set for "
                             + alarmSetForm.getAlarmTime());
 
         // The user wants to set the timer.
         // Cancels the currently running task, if any.
         if(task != null) {
            task.cancel();
            timer.cancel();
         }
 
         // Sets the timer task.
         task = new AlarmTask();
         task.setDisplayable(this, alarmForm);
         timer.schedule(task, alarmSetForm.getAlarmTime());
 
         // Goes back to the main screen.
         Display.getDisplay(this).setCurrent(mainForm);
      } else if (c == AlarmSetForm.CANCEL_COMMAND) {
         Display.getDisplay(this).setCurrent(mainForm);
      } else if (c == MainScreen.SET_ALARM_COMMAND) {
         Display.getDisplay(this).setCurrent(alarmSetForm);
      } else if (c == MainScreen.EXIT_COMMAND) {
         this.notifyDestroyed();
      } else if (c == AlarmForm.OK_COMMAND) {
         StringBuffer msg = new StringBuffer();
         msg.append("Last alarm occurred at ");
         msg.append(new Date(task.scheduledExecutionTime()));
         mainForm.setString(msg.toString());
         Display.getDisplay(this).setCurrent(mainForm);
      }
   }
}