sparkR.callJMethod {SparkR}

R Documentation

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.

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.

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.

Note

sparkR.callJMethod since 2.0.1

See Also

sparkR.callJStatic, sparkR.newJObject

Examples

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

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