Exception handling

R handling of java exception

# S3 method for Throwable
$(x, name )
	# S3 method for Throwable
$(x, name ) <- value

Arguments

x

condition

name

...

value

...

Details

Java exceptions are mapped to R conditions that are relayed by the stop function.

The R condition contains the actual exception object as the 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

.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 )
} )
# }