I need a little help here with extends.

[sandyw]

I need a little help here with extends.

I have three class
1. EventsClass
2. TicketClass I have the extends to EventsClass
3. BuyerClass. I have the extends to EventsClass

All three class have Accessors and Mutator Methods.
When I'm trying to create the Public buyterTracker
I get an error but it does not tell me what kind of error
Can someone help me please

lass buyerTracker extends EventClass{
	private String buyername;
	private String buyeraddr;

public [B]buyerTracker(String bn, String ba)[/B] {
		this.buyername = bn;
		this.buyeraddr = ba;

	}

	// accessors
	public String getBuyname() {
		return buyername;
	}

	public String getBuyeraddr() {
		return buyeraddr;
	}

	public void setBuyername(String bn) {
		buyername = bn;
	}

	public void setBuyerAddr(String ba) {
		buyeraddr = ba;
	}

	public String toString() {
	    return "(" + buyername + "," + buyeraddr + ")";
	}
}

Thanks
Sandy

[sandyw]

I need a little help here with extends.

I have three class
1. EventsClass
2. TicketClass I have the extends to EventsClass
3. BuyerClass. I have the extends to EventsClass

All three class have Accessors and Mutator Methods.
When I'm trying to create the Public buyterTracker
I get an error but it does not tell me what kind of error
Can someone help me please

class buyerTracker extends EventClass{
	private String buyername;
	private String buyeraddr;

public [B]buyerTracker(String bn, String ba)[/B] {
		this.buyername = bn;
		this.buyeraddr = ba;

	}

	// accessors
	public String getBuyname() {
		return buyername;
	}

	public String getBuyeraddr() {
		return buyeraddr;
	}

	public void setBuyername(String bn) {
		buyername = bn;
	}

	public void setBuyerAddr(String ba) {
		buyeraddr = ba;
	}

	public String toString() {
	    return "(" + buyername + "," + buyeraddr + ")";
	}
}

Thanks
Sandy

lass is suppost be class

[JosAH]

Did you read my previous tip of the week? It's in the Articles section now and
it discusses the Liskov Substitution Principle a bit.

There is no way you can come up with a TicketClass that *is* an EventClass
nor *is* a BuyerClass an EventClass. So inheritance that way is a total nono.
Did you read my latest reply in your other thread where you mentioned this
exact same subject?

An EventClass *has* Tickets (TicketClass) and the same holds for Buyer(Class).

kind regards,

Jos

[sandyw]

Did you read my previous tip of the week? It's in the Articles section now and
it discusses the Liskov Substitution Principle a bit.

There is no way you can come up with a TicketClass that *is* an EventClass
nor *is* a BuyerClass an EventClass. So inheritance that way is a total nono.
Did you read my latest reply in your other thread where you mentioned this
exact same subject?

An EventClass *has* Tickets (TicketClass) and the same holds for Buyer(Class).

kind regards,

Jos

They say this is the hard part getting the class right.
so if I have 3 class
1. TransferClass.( parent class)
2. EventClass extends TransferClass.
3. TicketClass extends EventClass.
4. BuyerClass extends TicketClass.

Sorry Jos but what will Transfer class do. Holds the infor from all the class?
Does
EventClass hold EventID, Concent, Seat Layout
TicketClass holds Date, time, price, Seat Number
BuyerClass holds Buyer name and address.

Sorry to be a pain in the you know what
thanks
Sandy
Ps I did read your article...

[JosAH]

They say this is the hard part getting the class right.
so if I have 3 class
1. TransferClass.( parent class)
2. EventClass extends TransferClass.
3. TicketClass extends EventClass.
4. BuyerClass extends TicketClass.

... and that makes four ;-)

Think of real events, say a theatre show. The event *has* tickets for sale and
buyers can buy tickets. Both the events and the buyers *have* zero or more
tickets. When a buyer buys a ticket s/he owns the ticket. Some tracking
mechanism or class associates tickets with buyers. The ticket has to know
about the event (a ticket is/was owned by an event and was/is possibly owned
by a buyer). That notion is encapsulated by a "transfer".

In this entire little scenario there is no inheritance present at all. Especially not
when you take that Liskov thing into account: a buyer *isn't* a ticket and a
ticket *isn't* a theatre show.

kind regards,

Jos

ps. no need to apologize for anything; try to be egoless when it comes to
class and class hierarchy design; it works better that way.