Simple helper functions for Java reflection

.jconstructors returns a character vector with all constructors for a given class or object. .jmethods returns a character vector with all methods for a given class or object. .jfields returns a character vector with all fields (aka attributes) for a given class or object.

Usage

.jconstructors(o, as.obj = FALSE, class.loader=.rJava.class.loader)
.jmethods(o, name = NULL, as.obj = FALSE, class.loader=.rJava.class.loader)
.jfields(o, name = NULL, as.obj = FALSE, class.loader=.rJava.class.loader)

Arguments

o

Name of a class (either notation is fine) or an object whose class will be queried

name

string, regular expression of the method/field to look for

as.obj

if TRUE then a list of Java objects is returned, otherwise a character vector (obtained by calling toString() on each entry).

class.loader

optional, class loader to use for class look up if needed (i.e., if o is a string)

Value

Returns a character vector (if as.obj is FALSE) or a list of Java objects. Each entry corresponds to the Constructor resp. Method resp. Field object. The string result is constructed by calling toString() on the objects.

Details

There first two functions are intended to help with finding correct signatures for methods and constructors. Since the low-level API in rJava doesn't use reflection automatically, it is necessary to provide a proper signature. That is somewhat easier using the above methods.

See also

.jcall, .jnew, .jcast or $,jobjRef-method

Examples

if (FALSE) { # \dontrun{
.jconstructors("java.util.Vector")
v <- .jnew("java.util.Vector")
.jmethods(v, "add")
} # }