Array: Create and access elements of Java arrays from R.
In SJava: The Omegahat interface for R and Java

Description Usage Arguments Details Value Author(s) References See Also Examples

These functions allow one to create multi-dimensional Java arrays via R commands using the .Java function. The get and set accessors work element-wise and not in the vector fashion common in R and S. One must create and initialize the Java virtual machine before calling any of these functions. See .JavaInit.

.JavaArrayConstructor(klass, ..., dim=length(list(...)), .name=NULL,
                      .convert=FALSE)
.JavaGetArrayElement(jobj,..., .name=NULL, .convert=TRUE)
.JavaSetArrayElement(jobj, value, ..., .dims=list(...), .convert=FALSE)
.JavaArrayLength(jobj)
## S3 method for class 'JavaArrayReference'
x[...]
## S3 replacement method for class 'JavaArrayReference'
x[...] <- value
## S3 method for class 'JavaArrayReference'
length(x)

`klass`	Typically a string (character vector of length 1) identifying the name of the class of the element type in the array to be created. This can also be a foreign reference to a Java class object obtained via an earlier call to `.Java`.
`...`	In the `.JavaArrayConstructor`, these are currently ignored. They are intended to be initializing values that are used to populate the top-level values of the new array. That is, they are used to set `arr[0], arr[1], arr[2], ...`. In the `JavaArrayReference` methods these are indicies passed to `.JavaGetArrayElement` and `.JavaSetArrayElement`.
`dim`	When creating an array in `.JavaArrayConstructor`, these specify both the number of dimensions and the length of each dimension in the array to be created.
`.dims`	When setting an array element in `.JavaSetArrayElement`, a `list` of `integer(1)` values corresponding to array dimensions of the element to be set.
`jobj, x`	This is the reference to the Java array returned from an earlier call to `.JavaArrayConstructor` or the return value from a call to `.Java`.
`value`	the object to be inserted as an element in the Java array. This is converted to a Java object using the usual conversion rules and then inserted into the Java array.
`.name`	The name to use to store the result in the omegahat named reference database. If this is missing, an anonymous reference is returned or the value converted to an R object. If the result of the Java method can be converted, this argument can be used to prohibit this conversion and leave the Java value in Omegahat for use in future `.Java` calls.
`.convert`	a logical value that indicates whether the Omegahat manager should attempt to convert the result of the method call. This is usually `TRUE`, but can be explicitly specified to avoid (arrays of) primitive object being converted to an R object when it is to be used in a subsequent `.Java` call.

This uses the .Java to call methods in the Omegahat Evaluator which process the array request.

.JavaArrayConstructor returns a reference to the newly create Java array object.

.JavaArrayLength returns a single integer giving the length of the top-level dimension of the array.

.JavaGetArrayElement returns the value of the specified element of the given array, converted to an R object as usual. Thus it may be a Java reference.

.JavaSetArrayElement returns NULL.

Duncan Temple Lang, John Chambers

http://www.javasoft.com, http://www.omegahat.org

.Java

if (!isJavaInitialized())
    .JavaInit(verbose=TRUE)
a <- .JavaArrayConstructor("java.lang.String", dim=3)
.JavaArrayLength(a)
.JavaSetArrayElement(a, "First", 1)
.JavaSetArrayElement(a, "Second", 2)
.JavaSetArrayElement(a, "Third", 3)
.JavaGetArrayElement(a, 2)