Reflection: Get a Class-Iinstance of a Wrapper Class

Reflection: Get a Class-Iinstance of a Wrapper Class - why .TYPE?

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Julian - 24 May 2005 09:47 GMT

Good morning,

can anyone explaine me the reason why every Wrapper-Class (like
Integer) has this special constant .TYPE? These Wrapper-Classes provide
the normal getClass()-Method as well and I therefore don't understand
the sense of the .TYPE constant.
Thank you very much in advance!

Greetings from sunny Kiel

Julian Wissel

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Roland - 24 May 2005 10:16 GMT

> Good morning,
>
[quoted text clipped - 7 lines]
>
> Julian Wissel

It represents the class of the *primitive*, i.e. not the class of the
wrapper class.

Wrapper Primitive
Integer.class int.class (== Integer.TYPE)
Character.class char.class (== Character.TYPE)
Float.class float.class (== Float.TYPE)
etc.

Used when obtaining a Method that has a primitive parameter. E.g. to get
the static method toString(int) of class Integer:

Integer.class.getDeclaredMethod("toString", new Object[]{Integer.TYPE});

or

Integer.class.getDeclaredMethod("toString", new Object[]{int.class});

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Regards,

Roland de Ruiter
___ ___
/__/ w_/ /__/
/ \ /_/ / \

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Dale King - 26 May 2005 04:46 GMT

>> Good morning,
>>
[quoted text clipped - 25 lines]
>
> Integer.class.getDeclaredMethod("toString", new Object[]{int.class});

And if you are wondering why we have two ways of doing the same thing,
the class literal (i.e. int.class) did not exist in the original version
of Java and were added later.

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Dale King

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Reflection: Get a Class-Iinstance of a Wrapper Class - why .TYPE?

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