OO class design

[Nicol Green]

Hi guys!

I have one more question about OO design. In my previous post "Class relations mass" I got great assistance from Pete Stein. Thank You Pete, once more for that. Here I have similar problem, and I don't know how to apply entirely suggested logic. I will appreciate help on this.

Now I have class View, where GUI is implemented.
I want to do caesar encryption, and a few more.
I was thinking to create Caesar class, Playfair, ..., Encryption class,
and View. Is this a good thinking, or do I need only Encryption class
and put all cipher implementations in that one ?
This is the Encryption class, but I am not sure how to define encryption, to
say so ? Could You, please, help me somehow ?

public class Encryption {

	private Caesar ceasar;
	private View view; // implements the GUI
	
	public String doEncryption(String message, int key){
			
		return message;
	
	}
}

Thank You!

[salvin francis]

First of all with MVC archiectecture, i suggest the following:

class Encryption
{
  //only encryption logic.
}

class View
{
  //creates an object of Encryption and uses it.
}

As an Optimization you might want to make Encryption's methods static ..


Next as you say you might change the encryption scheme later,

To this I suggest two approaches,

Approach 1 : Encryption contains type encryption Login.

class Encryption
{
  public int ENCRYPTION_CAESAR = 0;  
  public int ENCRYPTION_PLAYFAIR = 1;
  //Add more as you like later....

  private int encryptionType;

  public Encryption() //default constructor 'defaults' to using caesar encryption
  {
     this(ENCRYPTION_CAESAR);
  }
  public Encryption(int encryptionType)
  {
     this.encryptionType = encryptionType;
  }

   public String doEncryption(String message, int key){   
      //Encrypt according to encryptionType, maybe a switch-case statement
      return message;
   }
}

Approach 2: Decorator-based Pattern

will post this idea soon.....

[salvin francis]

Approach 2 : Decorator-based Pattern

interface EncryptionSchema
{
  public String doEncryption(String message, int key);
}
class CaesarEncryption implements EncryptionSchema
{
  public String doEncryption(String message, int key){      
      //Caesar based encryption
      return message;   
   }
}
class PlayFairEncryption implements EncryptionSchema
{
  public String doEncryption(String message, int key){      
      //PlayFair based encryption
      return message;   
   }
}

code can be written as :

EncryptionSchema encryptionSchema = new CaesarEncryption();  // or maybe new PlayFairEncryption();
encryptionSchema.doEncryption("message", "key");

This is not purely the decorator pattern though

[Nicol Green]

Thank You very much for your help, Salvin!

Maybe I like a bit more second approach.
I will go with it!

This is not purely the decorator pattern though

Sorry, this is new concept for me. I google it, but haven't find much.
Could You, please, give me a short explanation of it ? After that I suppose
I will see why this is not a "purely decorator pattern".Thanks!

[David Newton]

salvin francis wrote:As an Optimization you might want to make Encryption's methods static.

Whereas I would suggest you don't, since static methods can make testing more difficult, and any "optimization" you get is minimal at best.