High level API for accessing Java
J creates a Java class reference or calls a Java method
J(class, method, ..., class.loader=.rJava.class.loader)
class |
java object reference or fully qualified class name in JNI notation (e.g "java/lang/String" ) or standard java notation (e.g "java.lang.String") |
method |
if present then |
... |
optional parameters that will be passed to the method (if the
|
class.loader |
optional, custom loader to use if a class look-up
is necessary (i.e., if |
J is the high-level access to Java.
If the method argument is missing then code must be a
class name and J creates a class name reference that can be
used either in a call to new to create a new Java object
(e.g. new(J("java.lang.String"), "foo")) or with $
operator to call a static method
(e.g. J("java.lang.Double")$parseDouble("10.2").)
If the method argument is present then it must be a string
vector of length one which defines the method to be called on the
object.
If method is missing the the returned value is an object of
the class jclassName. Otherwise the value is the result of
the method invocation. In the latter case Java exceptions may be
thrown and the function doesn't return.
if (!nzchar(Sys.getenv("NOAWT"))) {
f <- new(J("java.awt.Frame"), "Hello")
f$setVisible(TRUE)
}
J("java.lang.Double")$parseDouble("10.2")
J("java.lang.Double", "parseDouble", "10.2" )
Double <- J("java.lang.Double")
Double$parseDouble( "10.2")
# String[] strings = new String[]{ "string", "array" } ;
strings <- .jarray( c("string", "array") )
# this uses the JList( Object[] ) constructor
# even though the "strings" parameter is a String[]
l <- new( J("javax.swing.JList"), strings)Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.