Casting from Object to int  
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gaztedo
PostPosted: 2007-12-20 19:44:00 Top
java-programmer, Casting from Object to int Hi there!

I'm developing a method which receives two Object parameters, and I need
to cast one of them to int. How can I do it?

public method(Object a, Object b){
this.b = (int)b; // doesn't work!
this.a = a;
}

Thanks in advance!
 
Sabine Dinis Blochberger
PostPosted: 2007-12-20 20:07:00 Top
java-programmer >> Casting from Object to int gaztedo wrote:

> Hi there!
>
> I'm developing a method which receives two Object parameters, and I need
> to cast one of them to int. How can I do it?
>
> public method(Object a, Object b){
> this.b = (int)b; // doesn't work!
> this.a = a;
> }
>
> Thanks in advance!

First of all, casting just means "lets treat this as if it were type x".
Why can't you require a parameter of type Integer or even int?
--
Sabine Dinis Blochberger

Op3racional
www.op3racional.eu
 
Sabine Dinis Blochberger
PostPosted: 2007-12-20 20:12:00 Top
java-programmer >> Casting from Object to int gaztedo wrote:

> Hi there!
>
> I'm developing a method which receives two Object parameters, and I need
> to cast one of them to int. How can I do it?
>
> public method(Object a, Object b){
> this.b = (int)b; // doesn't work!
> this.a = a;
> }
>
> Thanks in advance!

Please don't multipost. Read the FAQ, it was just posted by David Alex
Lamb.
--
Sabine Dinis Blochberger

Op3racional
www.op3racional.eu
 
 
Lew
PostPosted: 2007-12-20 21:38:00 Top
java-programmer >> Casting from Object to int gaztedo wrote:
>> I'm developing a method which receives two Object parameters, and I need
>> to cast one of them to int. How can I do it?
>>
>> public method(Object a, Object b){
>> this.b = (int)b; // doesn't work!
>> this.a = a;
>> }

Sabine Dinis Blochberger wrote:
> Please don't multipost. Read the FAQ, it was just posted by David Alex
> Lamb.

In the first place, gaztedo, 'int' is not an object type, so no Object can
ever be cast to 'int'. In the second place, there's no way to guarantee to a
public method that its argument values are of any particular subtype or value,
or conversely, that they aren't. These conditions therefore have to be
checked inside the method. Third, Sabine has given you a good idea about
letting the method signature determine the type as narrowly as you need.

Finally, although you named your code snippet 'method', you gave it the syntax
of 'constructor'. You must provide a return type for a method, e.g.,
public void foo( int a, int b ) { ... }

--
Lew
 
 
Matt Wharton
PostPosted: 2007-12-21 8:38:00 Top
java-programmer >> Casting from Object to int "gaztedo" <email***@***.com> wrote in message
news:476a558a$email***@***.com...
> Hi there!
>
> I'm developing a method which receives two Object parameters, and I need
> to cast one of them to int. How can I do it?
>
> public method(Object a, Object b){
> this.b = (int)b; // doesn't work!
> this.a = a;
> }
>
> Thanks in advance!

Refer to the advice others have given about good OO practices, etc (i.e.
what you are trying to do here probably is NOT the best way to go about
things). Having said that, you might try the following. If you are on Java
1.5 or higher, you can take advantage of auto-boxing/unboxing.

public void method(Object a, Object b)
{
if (b instanceof Integer)
{
this.b = (Integer)b; // Cast to Integer, not int. Will auto-unbox the
Integer as an int and store to this.b.
}

this.a = a;
}

Cheers,

-Matt

 
 
Vitvitskiy Vladimir
PostPosted: 2007-12-21 16:57:00 Top
java-programmer >> Casting from Object to int you can use this

public static void method(Object a, Object b) {
int bb = (Integer)b;
int aa = (Integer)a;
}

"gaztedo" <email***@***.com> wrote in message
news:476a558a$email***@***.com...
> Hi there!
>
> I'm developing a method which receives two Object parameters, and I need
> to cast one of them to int. How can I do it?
>
> public method(Object a, Object b){
> this.b = (int)b; // doesn't work!
> this.a = a;
> }
>
> Thanks in advance!


 
 
Roedy Green
PostPosted: 2007-12-22 3:54:00 Top
java-programmer >> Casting from Object to int On Fri, 21 Dec 2007 10:57:24 +0200, "Vitvitskiy Vladimir"
<email***@***.com> wrote, quoted or indirectly quoted
someone who said :

> public static void method(Object a, Object b) {
> int bb = (Integer)b;
> int aa = (Integer)a;

In JDK 1.5+ which has autounboxing.

In older Java you need to unbox manually.

int bb = ((Integer)b).intValue();
--
Roedy Green Canadian Mind Products
The Java Glossary
http://mindprod.com
 
 
 
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