Master Exam / Autoboxing

[John Stark]

In question 52 of Master Exam 2 the following statement is considered to be true: 'In some cases, is-a relationships are used in the process of autoboxing'.

Does anybody has an example? When an int is boxed to an Integer then this is not an is-a relationship I think (we cannot say 'int is-an Integer' as int is not an object')?

Thanks,

John

[s patnaik]

For example,

Number number = 10;

Here 10 which is an int is boxed to Integer. As, Integer "is a" Number, int 10 gets boxed and then widened to a Number. Or in other words, int 10 gets autoboxed to Number.

Hope that helps.

[Dan Drillich]

is-a relationship and autoboxing is another thread about this subject....

Regards,
Dan

[John Stark]

Number number = 10;

Doh, haven't thought about it. You can even do

Object o = 10;

Thanks for the answers,

John

[Matthew Brown]

The key thing to remember (and you may already have this), is that you can box-then-widen:

Number n = 10;

But you cannot widen-then-box:

Long ln = 10;

[John Stark]

The key thing to remember (and you may already have this), is that you can box-then-widen:

Number n = 10;

But you cannot widen-then-box:

Long ln = 10;

Yes, had taken me a while to understand this. Should be clear now

John