About Question enthuware.ocajp.i.v8.2.1447 :

[klimas]

Hi,

Please explain me the correct answer where :

Code: Select all

public void addUsage(int bytesUsed){     
if(bytesUsed>0){        
totalUsage = totalUsage + bytesUsed;        
totalBill = totalBill + bytesUsed*costPerByte;     
} 
}

while in the question is :

totalBill is always equal to totalUsage*costPerByte

Thank you

[admin]

Yes, the total bill in the given option also does equal totalUsage*costPerByte.

[Javier]

Hi!

I don´t understand the explanation of the last implementation, when says:
"Bandwidth class is now dependent on some other class".
Because if we do like before this sencence:" totalBill field will not reflect the correct amount unless User also calls updateTotalBill"

Why is not good to make the code in this way? (calling updateTotalBill in the User class)

Thank you very much Enthuware!

[admin]

Because you don't have control over how other users of your class may write their code. What if someone who is using this class doesn't make sure that updateTotalBill method is called?

[OCAJO1]

Would be correct to say whether the method in the correct choice is designated as public or protected is matter of business requirement rather than encapsulation rules?

[admin]

yes, that is correct.

[OCAJO1]

cool. so the next step - on this exam, if both versions are present, does public win?

[admin]

yes, if only one option has to be selected I would select public, but I'm pretty sure you will not get such option.

[aevora]

Yes, the total bill in the given option also does equal totalUsage*costPerByte.

Sorry but I don't see how they are equal. Could you provide an example?

Thanks.

[admin]

Yes, the total bill in the given option also does equal totalUsage*costPerByte.

Sorry but I don't see how they are equal. Could you provide an example?

Thanks.

Let's say the cost per unit is 10. So, if you call the addUsage method twice like this:

addUsage(10)// This will change totalBill to 0 + 10*10, i.e. 100.
addUsage(20)// This will change totalBill to 100 + 20*10, i.e. 300.

So, you can see that totalBill is always equal to total bytes consumed (i.e. 30) * costPerBye (i.e.10) = 300.

[aevora]

Thanks for the explanation, but I think you are mixing the variable totalUsage with totalBill.

"So, you can see that totalUsage is always equal to total bytes consumed (i.e. 30) * costPerBye (i.e.10) = 300."

totalUsage = totalUsage + bytesUsed;
totalBill = totalBill + bytesUsed*costPerByte;

So it is totalBill which is always equal to totalUsage * costPerByte, as you said here:

Yes, the total bill in the given option also does equal totalUsage*costPerByte.

[admin]

You are right. I have updated the post above to avoid confusion.
thank you for your feedback!