rJava (version 0.7-0)

JavaAccess: Field/method operator for Java objects

Description

The $ operator for jobjRef Java object references provides convenience access to object attributes and calling Java methods.

Details

rJava provies two levels of API: low-level JNI-API in the form of .jcall function and high-level reflection API based on the $ operator. The former is very fast, but inflexible. The latter is a convenient way to use Java-like programming at the cost of performance. The reflection API is build around the $ operator on jobjRef-class objects that allows to access Java attributes and call object methods.

$ returns either the value of the attribute or calls a method, depending on which name matches first.

$<- assigns a value to the corresponding Java attribute.

names returns all fields and methods associated with the object. Method names are followed by ( or () depending on arity. This use of names is mainly useful for code completion, it is not intended to be used programmatically.

This is just a convenience API. Internally all calls are mapped into .jcall calls, therefore the calling conventions and returning objects use the same rules. For time-critical Java calls .jcall should be used directly.

See Also

.jcall, .jnew, jobjRef-class

Examples

v <- .jnew("java/lang/String","Hello World!")
v$length()
v$indexOf("World")
names(v)