About Question enthuware.ocajp.i.v8.2.1451 :

[Deleted User 2655]

Can someone please explain to me why;

Code: Select all

bw.addMore(-bw.getAvailable()); will print 0?

[admin]

bw.getAvailable() returns 100, therefore when you pass -bw.getAvailable() to addMore, you are essentially passing -100 . addMore() performs 100+ (-100), which makes available = 0. That is why System.out.println(bw.getAvailable()); prints 0.

HTH,
Paul.

[Deleted User 2655]

Thanks Paul.

[Rinkesh]

Why is bw(0) wrong??

[admin]

Why is bw(0) wrong??

Well, this is a very basic programming question. bw is a variable and () can only be applied to a method name while invoking that method on a variable. For example, bw.addMore(0). So not sure why you think bw(0) makes sense? What do you think bw(0) means?

Looking at other questions that you have asked, I will suggest you to go through a good Java book to understand the basics before attempting mock exams. Otherwise, mock exams will not help you as much.

HTH,
Paul.

[wdphipps]

Hi team,

Hoping you can clear up some confusion for me.

I see in this question the explanation "Bandwidth class does not have a no-args constructor so this will not compile." is given as the reason for "bw = new Bandwidth();" being incorrect.

Wouldn't Java create a default constructor in this example?

My original guess is that this line is important:

"and a piece of code from another class:"

Thanks in advance,

-WP

[admin]

The default no args constructor is provided by the compiler only when there is no other constructor present in the class.

Which book are you following?

[wdphipps]

I'm using the latest book.

I looked further into the default constructor, it seems like I gained some understanding getting this wrong. I had understood that without a *no-args* constructor, a default would be created by the compiler. I know now that a default is only created if *no* constructor is given at all. This was also in the book:

"The compiler will complain that Account class does not have a constructor that takes no arguments. What happened to the default constructor, you ask? Well, since this class provides a constructor explicitly, the compiler feels no need to add one on its own."

Thanks for the help!

[wdphipps]

Now that i'm further in the book, I see how unnecessary my asking this question was. The default constructor is discussed at length further along this version of the book. Thanks again, team.