Ensures that a given object is an array reference
jcastToArray.Rd.jcastToArray takes a Java object reference of any kind and
returns Java array reference if the given object is a reference to an
array.
Arguments
- obj
Java object reference to cast or a scalar vector
- signature
array signature in JNI notation (e.g.
"[I"for an array of integers). If set toNULL(the default), the signature is automatically determined from the object's class.- class
force the result to pose as a particular Java class. This has the same effect as using
.jcaston the result and is provided for convenience only.- quiet
if set to
TRUE, no failures are reported and the original object is returned unmodified.
Value
Returns a Java array reference (jarrayRef) on success. If
quiet is TRUE then the result can also be the original
object in the case of failure.
Details
Sometimes a result of a method is by definition of the class
java.lang.Object, but the actual referenced object may be an
array. In that case the method returns a Java object reference instead
of an array reference. In order to obtain an array reference, it is
necessary to cast such an object to an array reference - this is done
using the above .jcastToArray function.
The input is an object reference that points to an array. Usually the
signature should be left at NULL such that it is determined
from the object's class. This is also a check, because if the object's
class is not an array, then the functions fails either with an error
(when quiet=FALSE) or by returning the original object (when
quiet=TRUE). If the signature is set to anything else, it is
not verified and the array reference is always created, even if it may
be invalid and unusable.
For convenience .jcastToArray also accepts non-references in
which case it simply calls .jarray, ignoring all other
parameters.
Examples
if (FALSE) { # \dontrun{
a <- .jarray(1:10)
print(a)
# let's create an array containing the array
aa <- .jarray(list(a))
print(aa)
ba <- .jevalArray(aa)[[1]]
# it is NOT the inverse, because .jarray works on a list of objects
print(ba)
# so we need to cast the object into an array
b <- .jcastToArray(ba)
# only now a and b are the same array reference
print(b)
# for convenience .jcastToArray behaves like .jarray for non-references
print(.jcastToArray(1:10/2))
} # }