Writing a generic class

[allen]

Hi,
I'm trying to write a wrapper class for an Object value using generics.
This is a basic example of my problem, my questions are the comments in
the code below:

class Wrapper<T> implements Cloneable
{
private T value = null;

public Wrapper<T> clone( ) throws CloneNotSupportedException
{
// In reality, I need to do some deep cloning of other fields not
// shown here, hence I need to cast the result of super.clone( ).
// How do I cast the following line correctly, to avoid warnings?
// This gives a warning:
Wrapper<T> clone = (Wrapper<T>) super.clone( );
// and this gives an error:
// Wrapper<T> clone = Wrapper<T>.class.cast( super.clone( ) );

return clone;
}

public T getValue( )
{
return value;
}
}

 

[Gijs Peek]

You could just suppress the warning:
....
@SuppressWarnings("unchecked")
public Wrapper<T> clone () throws CloneNotSupportedException
....
since Cloneable doesn't really contain the clone() method. You could also
create a subclass of Cloneable, but that really just moves the problem

 

[Roedy Green]

Wrapper<T> clone

do you meant that or simply T.

 

[Ian Pilcher]

You could just suppress the warning:
...
@SuppressWarnings("unchecked")
public Wrapper<T> clone () throws CloneNotSupportedException
...

Do you know of a compiler that actually supports the @SuppressWarnings
annotation?

 

[Oliver Wong]

Do you know of a compiler that actually supports the @SuppressWarnings
annotation?

Eclipse supports it.

- Oliver

 

[Thomas Hawtin]

Do you know of a compiler that actually supports the @SuppressWarnings
annotation?

Eclipse JDT and Sun's Java SE 6 javac (early access). Also, as a human I
can see the programmer saw and acknowledged the warning (or just hit the
editor's quick fix).

Tom Hawtin