SparkR (version 3.1.2)

sparkR.callJMethod: Call Java Methods

Description

Call a Java method in the JVM running the Spark driver. The return values are automatically converted to R objects for simple objects. Other values are returned as "jobj" which are references to objects on JVM.

Usage

sparkR.callJMethod(x, methodName, ...)

Arguments

x

object to invoke the method on. Should be a "jobj" created by newJObject.

methodName

method name to call.

...

parameters to pass to the Java method.

Value

the return value of the Java method. Either returned as a R object if it can be deserialized or returned as a "jobj". See details section for more.

Details

This is a low level function to access the JVM directly and should only be used for advanced use cases. The arguments and return values that are primitive R types (like integer, numeric, character, lists) are automatically translated to/from Java types (like Integer, Double, String, Array). A full list can be found in serialize.R and deserialize.R in the Apache Spark code base.

See Also

sparkR.callJStatic, sparkR.newJObject

Examples

# NOT RUN {
sparkR.session() # Need to have a Spark JVM running before calling newJObject
# Create a Java ArrayList and populate it
jarray <- sparkR.newJObject("java.util.ArrayList")
sparkR.callJMethod(jarray, "add", 42L)
sparkR.callJMethod(jarray, "get", 0L) # Will print 42
# }