I would like to have your advice about the way I have designed the application

[Varuna Seneviratna]

Below is the source code and the description of a Digital Clock application I created, I would like to have your advice about the way I have designed the application, I was influenced by the Digital clock application in the Book Objects first with Java byDavid J Barnes and Michael Kolling.The Clock calss creates two objects of the Hour and Minute classes and both of which creates two objects of Display class.The Clock class calls methods of Hour and Minute classes as approproate and in turn the objects of Hour and Minute call on the methods of the two Display objects they created

PROJECT TITLE: Digital Clock
PURPOSE OF PROJECT: Simulate a Digital Clock
VERSION or DATE: 23-April-2009
HOW TO START THIS PROJECT: Create an object of Clock(Use BlueJ to execute the project)
AUTHORS: Varuna Seneviratna
USER INSTRUCTIONS: If you want to change the format of the time displayed change the
parameters of the constructor where creating the Display object
(in the constructors of Hour and Minute classes), which will decide the format of the time displayed

The source code Clock class

  public class Clock
{
    // instance variables 
    private Hour hours;
    private Minute minutes;

    /**
     * Creates two objects of
     * Hour and Minute
     */
    public Clock()
    {
        hours =new Hour();
        minutes=new Minute();
        
    }

    /**
     * An example of a method - replace this comment with your own
     * 
     * @param  y   a sample parameter for a method
     * @return     the sum of x and y 
     */
    public int getMinute()
    {
        return minutes.getMinute();   
    }
    public int getHour()
    {
        return hours.getHour();   
    }
    
    public void DisplayTime()
    {
            int hour=getHour();
            int minute=getMinute();
            String displayHour="00";
            String displayMinute="00";
            
            if(hour <9 || minute < 9){
                if(hour < 9 ){
                    displayHour="0" + hour; 
            
                }
       
                if(minute < 9){
                    displayMinute="0" + minute;   
                }
                System.out.println(displayHour + ":" + displayMinute);
        }else{
            
            System.out.println(hour + ":" + minute);
        }
        
        
    }
    public void setTime(int hour, int minute)
    {
           hours.setHour(hour);
           minutes.setMinute(minute);
    }
    public void hourIncrement()
    {
        hours.increment();
        if(getHour()==0){
            minutes.increment();
        }
    }
    public void minuteIncrement()
    {
        minutes.increment();
        if(getMinute()==0){
            hours.increment();   
        }
    }
    
}  

Hour class

  public class Hour
{
    // instance variables
   private Display hourDisplay;
    

    /**
     * Constructor for objects of class Hour
     */
    public Hour()
    {
        hourDisplay=new Display(1, 12, 1);
       
    }
    

    /**
     * 
     * 
     * @param  No Parameters
     * @return  void 
     */
    public int getHour()
    {
        return hourDisplay.getValue();
        
        
    }
    public void setHour(int setValue)
    {
        hourDisplay.setValue(setValue);
    }
    public void increment()
    {
        hourDisplay.increment();   
    }
    public void displayHour()
    {
        String displayHour="";
        int hour=getHour();
        if(hour < 9){
            displayHour= "0" + hour;
            System.out.println(displayHour);
        }else{
            System.out.println(hour);   
        }
       
    }
    
}  

Minute class

 public class Minute
{
    // instance variables - replace the example below with your own
   private Display minuteDisplay;
    

    /**
     * Constructor for objects of class Hour
     */
    public Minute()
    {
        minuteDisplay=new Display(0, 59, 0);
       
    }

    /**
     * 
     * 
     * @param  No Parameters
     * @return  void 
     */
    public int getMinute()
    {
        return minuteDisplay.getValue();
        
    }
    public void setMinute(int setValue)
    {
        minuteDisplay.setValue(setValue);
    }
    public void increment()
    {
        minuteDisplay.increment();   
    }
    public void displayMinute()
    {
        int minute=getMinute();
        if(minute < 9 )
        {
            String displayMinute="0" + minute; 
            System.out.println(displayMinute);
        }else{
            System.out.println(minute);   
        }
           
    }
}   

Display class

  public class Display
{

    private int value;
    private int limit;
    private int rollOverTo;
    
    /**
     * The constructor, initializes value, limit and rollOverTo
     * @param int startValue, int rollOverLimit, int rollOverToValue
     * @return void
     */
    public Display(int startValue, int rollOverLimit, int rollOverToValue)
    {
        value=startValue;
        limit=rollOverLimit;
        rollOverTo=rollOverToValue;
        
    }
    
    /**
     * Increments the value until limit is reached, and
     * then rolls over to the rollOverTo
     * 
     * @param No Parameters
     * @return void
     * 
     */
    public void increment()
    {
           int tempValue=value;
           tempValue++;
           if(tempValue > limit)
           {
                  value=rollOverTo;
            }
            else{
                value++;   
            }
    }
    public void setValue(int newValue)
    {
        if(newValue >= rollOverTo && newValue <= limit)
        value=newValue;
    }
    /**
     * Returns the value
     * @param no parameters
     * @return int value
     */
    public int getValue()
    {
        return value;   
    }




}  

[Brian Legg]

Your code is object oriented, it's easy to read, and it works (I assume)... so I'd say congrats

I do think its overkill though... you could have written a program to do the exact same thing in less than 10 lines without the extra objects. Also, you never used the Date class... so it's not functional.

For a practice program though I like it... you've used a lot of different objects each which controls it's own properties

EDIT: On second thought, you would use the Calendar class... not the Date class which I had stated. Let me know if you'd like to see an example.

[Campbell Ritchie]

Are you sure you need Hour and Minute classes? Can you use Display classes with maximum (hour = 23, minute = 59) fields instead?