with and within methods for Java objects and class names
Convenience wrapper that allow calling methods of Java object and classes from within the object (or class).
## S3 method for class 'jobjRef' with(data, expr, ...) ## S3 method for class 'jobjRef' within(data, expr, ...) ## S3 method for class 'jarrayRef' with(data, expr, ...) ## S3 method for class 'jarrayRef' within(data, expr, ...) ## S3 method for class 'jclassName' with(data, expr, ...) ## S3 method for class 'jclassName' within(data, expr, ...)
data |
A Java object reference or a java class name. See |
expr |
R expression to evaluate |
... |
ignored |
The expression is evaluated in an environment that contains a mapping between the public fields and methods of the object.
The methods of the object are mapped to standard R functions in the environment. In case of classes, only static methods are used.
The fields of the object are mapped to active bindings (see makeActiveBinding) so that they can be accessed and modified from within the environment. For classes, only static fields are used.
with returns the value of the expression and
within returns the data argument
Romain Francois <francoisromain@free.fr>
the java.lang.reflect package:
https://docs.oracle.com/javase/8/docs/api/java/lang/reflect/package-summary.html
if (!nzchar(Sys.getenv("NOAWT"))) {
p <- .jnew( "java/awt/Point", 0L, 0L )
with( p, {
# x and y and now 0
move( 10L, 10L )
# x and y are now 10
x <- x + y
} )
f <- within( .jnew( "javax/swing/JFrame" ) , {
layout <- .jnew( "java/awt/BorderLayout" )
setLayout( layout )
add( .jnew( "javax/swing/JLabel", "north" ), layout$NORTH )
add( .jnew( "javax/swing/JLabel", "south" ), layout$SOUTH )
add( .jnew( "javax/swing/JLabel", "west" ), layout$WEST )
add( .jnew( "javax/swing/JLabel", "east" ), layout$EAST )
setSize( .jnew( "java/awt/Dimension", 400L, 400L ) )
setVisible( TRUE )
} )
}
Double <- J("java.lang.Double")
with( Double, MIN_VALUE )
with( Double, parseDouble( "10.2" ) )
## Not run:
# inner class example
HashMap <- J("java.util.HashMap")
with( HashMap, new( SimpleEntry, "key", "value" ) )
with( HashMap, SimpleEntry )
## End(Not run)
with( J("java.lang.System"), getProperty("java.home") )Please choose more modern alternatives, such as Google Chrome or Mozilla Firefox.