this code is violate OOP encapsulation concept, WHY ?

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1.00/5 (3 votes)

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C#

public class MyCalender
{

private String[] weekdays =
{ "Sun", "Mon", "Tue", "Thu", "Fri", "Sat", "Sun" };

public String[] getWeekdays()
{
return weekdays;
}
}

Posted 22-Jan-13 8:23am

Anderso0on

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Philippe Mori 22-Jan-13 18:46pm

You should tag with the proper language. And it look like an homework too...

2 solutions

Solution 3

I am not sure... I see C++ on the top... the sample looks like java... and using const String[]? Isn't final the keyword in java?

In any case, there are really some problems.
1 - Returning the array simple let users to change the items in the array.
2 - Even if you can return a constant array, that will be showing the real type of the array and in many situations it is exactly that what you should avoid. In fact, we know week days don't change, but imagine that you want to change from an array to a list, what will you do with the method? Will you change the return type?

Conclusion: You should not return an array, you should return something that does not compromises the internal representation. You could do it by:
1 - Creating a getCount method and a getWeekDayName, which receives the day by index and returns the String representing it;
2 - By returning some kind of unchangeable collection that can point to an array, list or other.

In any case, you must also take care not to allow users to change the values.

Posted 22-Jan-13 9:12am

Paulo Zemek

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Philippe Mori 22-Jan-13 18:45pm

The code is in C# (even though the OP has tagged it as C++) but your points are good.

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fjdiewornncalwe · Accepted Answer · 2013-01-22T08:30:00

Solution 1

By returning the private String[] object through the public method you are also giving the outside world read/write access to the contents of the object.
To satisfy the concept you would need to do it this way:

C++

public class MyCalendar
{
   private String[] weekdays = 
      { "Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat", "Sun" };

   public const String[] getWeekdays()
   {
      return weekdays;
   }
}

Now you are allowing the outside world to read the Days of the Week, but now the outside world cannot change the contents of the object.

Posted 22-Jan-13 8:30am

fjdiewornncalwe

Comments

Anderso0on 22-Jan-13 14:32pm

const what do here ??

Jibesh 22-Jan-13 15:49pm

check the last line of the solution. it explains what const will do.
'the outside world cannot change the contents of the object'

fjdiewornncalwe 22-Jan-13 17:00pm

Thanks, jibesh.

Sergey Alexandrovich Kryukov 22-Jan-13 14:37pm

Right, a 5. A very good approach would be an index operator used to return an array element.
—SA

fjdiewornncalwe 22-Jan-13 17:00pm

very true.