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\name{Exceptions}
\alias{Exceptions}
\alias{$.Throwable}
\alias{$<-.Throwable}
\title{Exception handling}
\description{R handling of java exception}
\usage{
\S3method{$}{Throwable}(x, name )
\S3method{$}{Throwable}(x, name ) <- value
}
\arguments{
\item{x}{condition}
\item{name}{...}
\item{value}{...}
}
\details{
Java exceptions are mapped to R conditions that are relayed by the
\code{\link{stop}} function.
The R condition contains the actual exception object as the
\code{jobj} item.
The class name of the R condition is made of a vector
of simple java class names, the class names without their package
path. This allows the R code to use direct handlers similar to
direct exception handlers in java. See the example below.
}
\examples{
\dontshow{.jinit()}
Integer <- J("java.lang.Integer")
tryCatch( Integer$parseInt( "10.." ), NumberFormatException = function(e){
e$jobj$printStackTrace()
} )
# the dollar method is also implemented for Throwable conditions,
# so that syntactic sugar can be used on condition objects
# however, in the example below e is __not__ a jobjRef object reference
tryCatch( Integer$parseInt( "10.." ), NumberFormatException = function(e){
e$printStackTrace()
} )
\dontshow{
tryCatch( Integer$parseInt( "10.." ), NumberFormatException = function(e){
classes <- class( e )
stopifnot( "NumberFormatException" \%in\% classes )
stopifnot( "Exception" \%in\% classes )
stopifnot( "Object" \%in\% classes )
stopifnot( "error" \%in\% classes )
stopifnot( "condition" \%in\% classes )
} )
}
}
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