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<H1><A NAME="SECTION03550000000000000000">
Casting Objects</A>
</H1>
<P>
In some cases it is necessary to cast the internal representation of
an object as well as the Java object. (For example, getting an object
from a SIDL array of superclass objects.) In these cases a Java cast is
insufficient. Therefore we have provided two casting functions.
<P>
<A NAME="9062"></A><TT>_cast(object)</TT> is a static function included with every SIDL
class that returns object passed in to cast that class. For example, in
order to cast an object of type <TT>sidl.BaseClass</TT> to
<TT>foo.Bar</TT> simply write <TT>foo.Bar newobj = (foo.Bar) foo.Bar._cast(oldobj)</TT>.
If this is an invalid cast, <TT>_cast</TT> will return <TT>null</TT>.
<P>
The alternative is <TT>_cast2(``ClassName'')</TT>. This is a cast
function that is included with every SIDL object. It performs
basically the same function as <TT>_cast</TT>, but the form is
<TT>object._cast2(``ClassName'')</TT>. It takes a fully qualified
class name. If the cast is invalid, or a class of that name cannot be
found, this function returns <TT>null</TT>.
<P>
Both of these functions
return a <TT>sidl.BaseClass</TT> which then must be Java casted to the
correct Java class type. Also, in casting, they both create a new
Java object that owns a new reference to the IOR object.
<A NAME="9074"></A> In Java you
never have to worry about reference counting, but this does mean that
the pre-cast object still exists and is valid.
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