Homework 4
Understanding Class Definitions

Overview - The purpose of the homework is to review Chapter 3 concepts and additional practice skills needed throughout the course. 

Problem description - Chapter 3 implemented a ClockDisplay class which will be extended to include alarm clock features.

An alarm clock holds the alarm hour and minute, which it compares on every tick with the current hour and minute. If the alarm is on and the alarm hour and minute equal the clock hour and minute, the alarm is sounded. The alarm hour and minute can be set, and the alarm can be turned on and off.

Assignment

From the View menu, Show Terminal, then Record method calls. Clear the window before starting.

• ClockDisplay
  1. Exercise a
     • Add to ClockDisplay class a printTime method to print displayString to the terminal window, use the getTime method.
     • Create a ClockDisplay instance and calling printTime.

      

  2. Exercise b - Add fields.
     • Add two fields for the alarm hour and minute, alarmHour and alarmMinute, of the NumberDisplay class.
     • Add a field alarm of type boolean.
     • Modify both ClockDisplay constructors to:
       • initialize alarm to false,
       • initialize alarmHour and alarmMinute fields to NumberDisplay limits of 24 and 60 respectively (i.e. as is already done for hours and minutes in ClockDisplay).
     • Create an instance for both constructors and Inspect to verify.

      

  3. Exercise c - Debugger
     • Set a breakpoint in the public ClockDisplay(int hour, int minute) constructor at the statement:
       • hours = new NumberDisplay(24);
     • Create an instance using the constructor.
     • Click Step until each NumberDisplay constructor has been called.
     • In Debugger window, double-click on alarmHour to open an Inspector window.
     • Copy the Debugger and Inspector window to a Word document.
     • Click Continue to complete constructor execution.
        
  4. Exercise d
     • Add a mutator method setAlarm that sets alarmHour and alarmMinute fields. Neither field should be changed if either the alarm hour parameter is negative or above 23, or alarm minute parameter is negative or above 59.
       • Hint: Call the NumberDisplay setValue() on each of the two fields.
     • Add a method printAlarm method to print alarmHour and alarmMinute fields to the terminal window in the form of:

       hour : minute

       Hint: Use getValue() method.

     • Create a ClockDisplay instance.
     • Set a breakpoint at the first statement of setAlarm.
     • For each of the following 3 tests:
       • Execute the setAlarm method.
       • Click Step one time to execute the if-statement of the method to determine the next statement executed.
       • Copy Debugger window to the Word document.
       1. Set the alarm to 13:27 and print the alarm setting.
       2. Set the alarm to -13:27 and print the alarm setting.
       3. Set the alarm to 24:27 and print the alarm setting.
           
  5. Exercise e
     • Add mutator methods alarmOn that sets alarm field true and alarmOff that sets alarm field false.
     • Create an instance and Inspect to verify when calling each method.

      

  6. Exercise f
     • Add method printBeep that:
       • prints "Beep Beep Beep" to terminal window
       • calls printAlarm method
     • Create an ClockDisplay instance and call printBeep method.

        

  7. Exercise g
     • Add a method checkAlarm that:
       • if
         • alarm is true and
         • the value (use getValue method) of alarmHour equals hours and
         • the value (use getValue method) of alarmMinute equals minutes
       • then call the printBeep method
       • else do nothing
     • In method timeTick() add a call to method checkAlarm() after the call to updateDisplay(). This will check the alarm for each clock tick.
     • Create an instance
       • call setTime method to set clock time to 13:27
       • call setAlarm method to set alarm time to 13:29
       • call alarmOn method to set alarm to true
       • call timeTick method 3 times
       • You should see "Beep Beep" in the Terminal window.
          
  8. Exercise h.
     • Add sound using SoundClass
       • Create a new class named SoundClass. Copy and paste the following as the new class definition:

         import java.applet.*; import java.io.*; import java.net.*; public class SoundClass {    public void play(String fileName)    {       AudioClip testClip;       URL testUrl;       try{             testUrl=new URL("file:" + new File(".").getCanonicalPath() + "/" + fileName);             testClip=Applet.newAudioClip(testUrl);             testClip.play();       } catch(Exception e){ System.out.println(e.toString()); }    } }

       • Download and save a WAV file into the same directory as your Java file.
       • To test, create a SoundClass object and call the play() method using the WAV file name as the parameter, (e.g. "HW4.wav").
       • You may want to record or use a different WAV file.
          
     • Add a method soundAlarm to ClockDisplay that:
       • creates a SoundClass object by:

         SoundClass sound = new SoundClass();

       • plays a WAV sound file using the SoundClass  and play() method described above.
       • To test, create a ClockDisplay instance and call the soundAlarm() method.
          
     • Modify the checkAlarm method to call both the printBeep() and soundAlarm() methods at the same time.
        
     • Create a ClockDisplay instance
       • call setTime method to set clock time to 13:27
       • call setAlarm method to set alarm time to 13:29
       • call alarmOn method to set alarm to true
       • call timeTick method 3 times
       • "Beep Beep" should print and the annoying alarm sound should play.
          
  9. Copy the complete ClockDisplay source code and Terminal Window to Word and save as HW4 document.

Turn in

C201 OnCourse Dropbox - Place the Word document in C201 OnCourse dropbox as HW4.