Clarification about Widening

[James Tharakan]

Its about widening.
I always think if i am right or wrong.
As far as i understood,
Widening of primitive datatypes means, moving upwards.i.e
byte-> short-> int-> long->float->double.

Widening at objects level means,

[B] 
  short->Short->|
    byte->Byte->|
  int->Integer->|  ->Number -> Object
    long->Long->|
  float->Float->|
double->Double->|[/B]

Hope i am right, if not, correct me

[ December 16, 2008: Message edited by: James Tharakan ]
[ December 17, 2008: Message edited by: James Tharakan ]

[Preethi Dev]

Hi James,
I think this is correct,
byte->short-> int-> long->float->double.

Preetha

[James Tharakan]

I am still looking for answers ! !

[Ankit Garg]

Originally posted by James Tharakan:
I am still looking for answers ! !

Did you see the answer by Preetha Arun??

[Rajshekhar Paul]

Yes, you are right James except when you say
int->Integer->Number->Object, for example.
In the above case, int is boxed to Integer first and then widening is applied.

In general widening means going to class/interface which is more general, on contrary narrowing means moving to more specific classes.

[Punit Singh]

James, there is no widening is at object level.

If primitive type int is converted to wrapper Integer, it is called boxing.

int----> Integer is boxing.
Integer---> int is unboxing.

Now boxing and unboxing are done by compiler, so it is called autoboxing and autounboxing.

If Integer is converted to Number, it is called upcasting or implicit casting, as it happens implicitly.
If Number is converted to Integer, it is called downcasting or explicit casting, as we have to do it explicitly.
like:
Number n;
Integer i=(Integer)n;

[Rajshekhar Paul]

@punit
When you say 'autounboxing', you are wrong. It's 'unboxing' basically. And I think the usage of word 'widening' in case of object level is also meaningful.
[ December 17, 2008: Message edited by: Rajshekhar Paul ]

[James Tharakan]

Originally posted by Ankit Garg:


Did you see the answer by Preetha Arun??

Well,Ankit, that was not complete.


And thanks Rajshekhar Paul , Now things are clear.

[Ankit Garg]

Originally posted by James Tharakan:

Well,Ankit, that was not complete.

No problems . By the way nice thought in your signature James