Java calls R

Environment: Win7 32-bit jdk1.7 R 2.15.0

Java calls R there are three main ways, Rjava,rserver and Rcaller, the main talk here with Rjava call

Rjava is a communication interface between the R language and the Java language, implemented by the underlying JNI implementation, allowing direct invocation of Java objects and methods in R. Because Rjava is the underlying interface and is invoked using JNI as an interface, it is very efficient. In the Jri scenario, the JVM directly loads RVM directly through memory, and the call process performance is virtually lossless, making it a very efficient connection channel and a preferred development package for R and Java communications.

Before using R3.0.2, do not know whether the version is too high reason,

The process of using Rjava to implement Java calls R, such as printing variables, can be successful
String Version = Re.eval ("r.version.string"). Asstring (); SYSTEM.OUT.PRINTLN (version);
The case of defining variables can also
Rexp x=re.eval ("1:10");
System.out.println ("rexp result =" +x);
Re.eval ("Print (1:10/3)");

But when it comes to invoking basic functions, it is the error of the general report null pointer.
Like what
Re.eval ("Rnorm (10)");
Double[] arr =re.eval ("Rnorm (Ten)"). Asdoublearray ();

Or in the test code that comes with it.
Rexp x;
Re.eval ("Data (Iris)", false);
System.out.println (X=re.eval ("Iris"));

To get to the point, first open R software,

Install.packages ("Rjava")

If the library (Rjava) does not make an error, it indicates that the first step was successful.

Start the JVM

. Jinit ()

S <-. Jnew ("java/lang/string", "Hello world!")

S

[1] "Java-object{hello world!}"

Then set the environment variable
Classpath=d:\prosoftware\r-2.15.0\library\rjava\jri;
Path=d:\prosoftware\r-2.15.0\bin\i386
R_home=d:\prosoftware\r-2.15.0\r-2.15.0\

Copy the three jar packages (Jriengine.jar,jri.jar,rengine.jar) under D:\proSoftware\R-2.15.0\library\rJava\jri to C:\Program files\java\ Jdk1.6.0_10\lib directory, that is, the JDK directory under the Lib

Open Eclipse and create Java project. The above three packages are also imported into the project.

The D:\proSoftware\R-2.15.0\library\rJava\jri\examples directory has two self-test codes Rtest.java and Rtest2.java.

Run both code, if the result is not an error, the call succeeds.

Before running, remember to add the VM parameter set to-djava.library.path=d:\prosoftware\r-2.15.0\library\rjava\jri in run configurations

Java calls R