,
Alex M Chubaty [ctb] ,
His Majesty the King in right of Canada [cph]| Title: | Create 'Java' Objects and Execute 'Java' Methods |
|---|---|
| Description: | Makes it possible to create 'Java' objects and to execute 'Java' methods from the 'R' environment. The 'Java' Virtual Machine is handled by a gateway server. Commands are sent to the server through a socket connection from the 'R' environment. Calls to 'Java' methods allow for vectors so that a particular method is iteratively run on each element of the vector. A score algorithm also makes the calls to 'Java' methods less restrictive. The gateway server relies on the runnable 'Java' library 'j4r.jar'. This library is licensed under the LGPL-3. Its sources are included in the jar file. |
| Authors: | Mathieu Fortin [aut, cre] ,
Alex M Chubaty [ctb] ,
His Majesty the King in right of Canada [cph] |
| Maintainer: | Mathieu Fortin <[email protected]> |
| License: | LGPL-3 |
| Version: | 1.2.3 |
| Built: | 2024-11-27 04:09:19 UTC |
| Source: | https://github.com/CWFC-CCFB/J4R |
This function makes it possible to add a directory or a JAR file to the class path. If the packageName parameter is null then the urlString parameter must be the complete path to the directory. Otherwise, it can be the name of the JAR file and the function will find the path through the package name. A non null packageName parameter is typically used in packages that rely on J4R. IMPORTANT This function is not compatible with Java 16 and later.
addToClassPath(path, packageName = NULL)addToClassPath(path, packageName = NULL)
path |
a character representing the path to the directory or the JAR file if the packageName parameter is null. Otherwise, it can just be the name of the JAR file. This path is normalized so that expressions like myJar.jar or ./extensions/myJar.jar will be processed. |
packageName |
a character representing the package. |
This function makes it possible to add a directory or a JAR file to the class path. If the packageName parameter is null then the urlString parameter must be the complete path to the directory. Otherwise, it can be the name of the JAR file and the function will find the path through the package name. A non null packageName parameter is typically used in packages that rely on J4R.
addUrlToClassPath(urlString, packageName = NULL)addUrlToClassPath(urlString, packageName = NULL)
urlString |
a character representing the complete path to the directory or the JAR file if the packageName parameter is null. Otherwise, it can just be the name of the JAR file. |
packageName |
a character representing the package. |
This function is deprecated. Use the addToClassPath function instead.
Cast the object into a Java float type
as.float(obj)as.float(obj)
obj |
a numeric or a vector of numerics |
Converts an R array into a Java array.
as.JavaArray(values, affinity. = 1)as.JavaArray(values, affinity. = 1)
values |
a vector or a matrix |
affinity. |
an optional parameter for multithreading (see the mclapply.j4r function) |
a java.object reference that points a Java array
Cast the object into a Java long type
as.long(obj)as.long(obj)
obj |
a numeric or a vector of numerics |
The buffer has a length of 100Kb by default.
bufferLengthbufferLength
An object of class numeric of length 1.
This environment contains the objects that enable the connection to the gateway server.
cacheEnvcacheEnv
An object of class environment of length 0.
This function call the garbage collector in R and sends the list of Java references that have been collected to the Java server. These references are then removed from the internal map.
callJavaGC()callJavaGC()
This function calls a public method in a particular class of object. If the javaObject parameters or the additional parameters (...) include vectors, the method is called several times and a vector of primitive or a list of java instances can be returned.
callJavaMethod(source, methodName, ..., affinity = 1)callJavaMethod(source, methodName, ..., affinity = 1)
source |
this should be either a java.list instance or a single java.object instance for non-static methods or a string representing the Java class name in case of static method |
methodName |
the name of the method |
... |
the parameters of the method |
affinity |
a parameter used by the mclapply.j4r function in case of multithreading. |
There is no need to cast a particular parameter to a super class. Actually, the Java server tries to find the method that best matches the types of the parameters. Primitive type are converted on the fly, numeric to double, integer to int, logical to boolean and character to String. Factors are also converted to String.
When the source is a java.object instance, this function can be substituted for the $ operator.
It depends on the method. It can return a primitive type (or a vector of primitive), a Java instance (or a list of Java instances) or nothing at all.
### starting Java connectToJava(memorySize = 200) ### creating an empty ArrayList object myList <- createJavaObject("java.util.ArrayList") ### adding 3 to the list callJavaMethod(myList, "add", 3) ### adding 5 to the list myList$add(3) ### shutting down Java shutdownClient()### starting Java connectToJava(memorySize = 200) ### creating an empty ArrayList object myList <- createJavaObject("java.util.ArrayList") ### adding 3 to the list callJavaMethod(myList, "add", 3) ### adding 5 to the list myList$add(3) ### shutting down Java shutdownClient()
It checks if a particular library is part of the classpath.
checkIfClasspathContains(myJavaLibrary)checkIfClasspathContains(myJavaLibrary)
myJavaLibrary |
a character string that stands for the java library (e.g. repicea.jar) |
This function connects the R environment to a gateway server that runs in Java.
connectToJava( host = "localhost", ports = c(0, 0), extensionPath = NULL, memorySize = NULL, public = FALSE, internalPorts = c(0, 0), key = NULL, headless = T )connectToJava( host = "localhost", ports = c(0, 0), extensionPath = NULL, memorySize = NULL, public = FALSE, internalPorts = c(0, 0), key = NULL, headless = T )
host |
the URL or IP address of the host ("localhost" by default ) |
ports |
a vector of the listening ports for the Java server |
extensionPath |
a vector of characters that contains the paths to jar files or to the classes that are to be loaded by the system classloader. |
memorySize |
the memory size of the Java Virtual Machine in Mb (if not specified, the JVM runs with the default memory size) |
public |
true to connect to a server that is already running locally (FALSE by default) |
internalPorts |
a vector of two integers representing the backdoor port and the garbage collector port |
key |
an integer used as a token to ensure a secure connection |
headless |
a boolean to enable the headless mode (is true by default). |
The first argument of the function provides the listening ports for the Java server. A maximum of four ports is allowed. When set to 0, these ports are randomly selected. By default, the server listens to two random ports.
The extensionPath can either be set in this function or dynamically changed (see the addToClassPath function). However, dynamic classpath changes are not allowed in Java version later than 16.
The headless mode assumes the JVM has no keyboard, display or mouse. In order to enable the UI on the Java end, the headless argument should be set to false.
a logical TRUE if the function managed to get connected to the server or if it was already connected or FALSE if the connection has failed
This function creates one or many object of a particular class. If the parameters contain vectors, then a series of instances of this class can be created. Primitive type are converted on the fly, numeric to double, integer to int, logical to boolean and character to String. Factors are also converted to String.
createJavaObject( class, ..., isNullObject = FALSE, isArray = FALSE, affinity = 1 )createJavaObject( class, ..., isNullObject = FALSE, isArray = FALSE, affinity = 1 )
class |
the Java class of the object (e.g. java.util.ArrayList) |
... |
the parameters to be passed to the constructor of the object |
isNullObject |
a logical that indicates whether the instance should be null (by default it is set to FALSE) |
isArray |
a logical that indicates whether the instance is an array. By default, it is set to FALSE. When creating an array, the parameters must be integers that define the dimensions of the array |
affinity |
a parameter used by the mclapply.j4r function in case of multithreading. |
a java.object or java.list instance in the R environment
### starting Java connectToJava(memorySize = 200) ### creating an empty ArrayList object createJavaObject("java.util.ArrayList") ### creating an ArrayList instance with initial capacity of 3 createJavaObject("java.util.ArrayList", as.integer(3)) ### creating two ArrayList with different capacities createJavaObject("java.util.ArrayList", c(as.integer(3), as.integer(4))) ### creating a 3x3 array of integers myArray <- createJavaObject("int", 3, 3, isArray = TRUE) ### creating two arrays of integers with length 3 myArrays <- createJavaObject("int", c(3,3), isArray = TRUE) ### shutting down Java shutdownClient()### starting Java connectToJava(memorySize = 200) ### creating an empty ArrayList object createJavaObject("java.util.ArrayList") ### creating an ArrayList instance with initial capacity of 3 createJavaObject("java.util.ArrayList", as.integer(3)) ### creating two ArrayList with different capacities createJavaObject("java.util.ArrayList", c(as.integer(3), as.integer(4))) ### creating a 3x3 array of integers myArray <- createJavaObject("int", 3, 3, isArray = TRUE) ### creating two arrays of integers with length 3 myArrays <- createJavaObject("int", c(3,3), isArray = TRUE) ### shutting down Java shutdownClient()
All the elements of an array are returned. If these elements are Java instances, then the function value is a java.list of java.object references. Otherwise, the value is either a vector or a matrix
getAllValuesFromArray(object, affinity. = 1)getAllValuesFromArray(object, affinity. = 1)
object |
a java.object reference pointing to a Java array |
affinity. |
an optional parameter for multithreading (see the mclapply.j4r function) |
either a java.list object, a vector or a matrix
All the elements of a Java List instance are returned.
getAllValuesFromListObject(object, affinity. = 1)getAllValuesFromListObject(object, affinity. = 1)
object |
a java.object that represents a List instance in Java |
affinity. |
an optional parameter for multithreading (see the mclapply.j4r function) |
either a java.list object or an R vector
This method returns an integer that is the length of the Array.
getArrayLength(object, affinity. = 1)getArrayLength(object, affinity. = 1)
object |
a java.object instance that represents an array |
affinity. |
an optional parameter for multithreading (see the mclapply.j4r function) |
an integer that is the length of the array
This functions returns the paths that are currently included in the System classloader.
getClassLoaderPaths()getClassLoaderPaths()
This function returns the URLs that are currently included in the System classloader.
getClassLoaderURLs()getClassLoaderURLs()
This function is deprecated. Please use the getClassLoaderPaths instead.
Return the architecture of the Java installation, i.e. either 32-Bit or 64-Bit. It actually returns the second slot of the list produced by the getJavaVersion function.
getJavaArchitecture()getJavaArchitecture()
the architecture, i.e. 32-Bit or 64-Bit
getJavaVersion
This function gets the value of a particular field, which can be either static or not. If the field is static, the source should be a valid class name.
getJavaField(source, fieldName, affinity = 1)getJavaField(source, fieldName, affinity = 1)
source |
this should be either a java.list instance or a single java.object instance for non-static methods or a string representing the Java class name in case of static method |
fieldName |
the name of the field to be set |
affinity |
a parameter used by the mclapply.j4r function in case of multithreading. |
When the source is a java.object instance, this function can be substituted for the $ operator.
Returns the current Java version either through the command line if not connected to the Java server or through the Java server if connected.
getJavaVersion()getJavaVersion()
a list with the first slot (version) being the version and the second slot (architecture) referring to the 32-Bit or 64-Bit architecture
getJavaArchitecture
The function provides the list of the Java references in an environment.
getListOfJavaReferences(envir = .GlobalEnv)getListOfJavaReferences(envir = .GlobalEnv)
envir |
the environment to be scanned for java.object and java.list instances. By default, it is the global environment |
By default this function provides the Java reference in the current environment. If there is no Java references then the value of the function is an empty list. If just.names is set to true, the value is a vector with the names of the instances. If false, then the function returns a list with the instances.
a vector with the names of the instances
An instance of a particular class can be associated to a public server. The approach is similar to that of Py4j package, where the gateway server is just a channel to get to a particular instance. This R function retrieves this instance.
getMainInstance()getMainInstance()
a java.object instance or null if the main instance was not set
This is a Java reference for convenience.
getMainLoggerInstance()getMainLoggerInstance()
a reference to the main Logger instance on the Java end
This function calls the Runtime static methods maxMemory(), totalMemory() and freeMemory(). The results are divided by 1024 in order to report the memory sizes in Mb.
getMemorySettings()getMemorySettings()
a data.frame object with the maximum, total and free memory in Mb.
The number of connections to the server
getNbConnections()getNbConnections()
the number of sockets connected to the server
Return the number of instances stored in the internal map of the Java server
getNbInstancesInInternalMap()getNbInstancesInInternalMap()
an integer
This function returns the value at location given by the index parameter.
getValueFromArray(object, ..., affinity. = 1)getValueFromArray(object, ..., affinity. = 1)
object |
a java.object that represents an array |
... |
a series of integers that correspond to the index of the value. Note that in Java the first index is 0 |
affinity. |
an optional parameter for multithreading (see the mclapply.j4r function) |
the value at the location
Interrupt the current task on the Java server
interruptJava()interruptJava()
This function returns true if the Java instance represented by this java.object is an Array.
is.JavaArray(object)is.JavaArray(object)
object |
a java.object instance |
a logical
This is done by checking f the socket connection to the JVM exists.
isConnectedToJava()isConnectedToJava()
a logical
This function returns true if the Java instance represented by this java.object is an Array.
isJavaArray(object)isJavaArray(object)
object |
a java.object instance |
This function is deprecated. Please use the is.JavaArray instead.
The current version of the J4R Java server
J4R_Server_VersionJ4R_Server_Version
An object of class character of length 1.
Allows to specify a default JVM size in Mb so that the option memorySize in hte connectToJava function does not need to be used.
j4r.config.setDefaultJVMMemorySize(defaultJVMMemory)j4r.config.setDefaultJVMMemorySize(defaultJVMMemory)
defaultJVMMemory |
the number of Mb for the JVM (must be equal to or greater than 50). If set to NULL, this option has no effect. |
It enables or disable the verbose in the J4R package. By default, the verbose is disabled.
j4r.config.setVerbose(verbose)j4r.config.setVerbose(verbose)
verbose |
a logical |
This is the not so gentle way to exit the JVM.
killJava()killJava()
In case the JVM is stuck and does not respond to interrupt. It is possible to force the shutdown through this function.
A java.list class is an environment containing an inner list. The length of this inner list is returned by this function.
## S3 method for class 'java.list' length(x)## S3 method for class 'java.list' length(x)
x |
a java.list instance |
the length of the inner list
A java.object class is a list by definition. However, its length is 1.
## S3 method for class 'java.object' length(x)## S3 method for class 'java.object' length(x)
x |
a java.object instance |
1
A maximum length of the vector is set in order to avoid buffer size issues when reading
maxVectorLengthmaxVectorLength
An object of class numeric of length 1.
Applies the mclapply function in the context of the J4R package.
mclapply.j4r(X, FUN, ..., nbCores = getNbConnections())mclapply.j4r(X, FUN, ..., nbCores = getNbConnections())
X |
a vector of numerics |
FUN |
a two-argument function. The first argument is called by the mclapply function and the second argument defines the affinity and MUST be used in all the calls to the createJavaObject, callJavaMethod, getJavaField and setJavaField functions. |
... |
optional arguments to FUN (see mclapply) |
nbCores |
the number of threads to be used. By default, this argument is set to the number of available connections. |
Multithreading a function requires that the Java code is thread safe. The server must listen to at least two ports. Otherwise, this function will reduce to a single thread. Each port is given an affinity to an R thread.
The multithreading is not available on Windows. In such a case, the function will proceed in a single thread. The $ operator should not be used to substitute the getJavaField and setJavaField functions because it does not allow for the specification of the affinity. Use the original getJavaField and setJavaField functions. The $ operator can be used to call functions though as in the example below.
mclapply in the parallel package
## Not run: f <- function(i, aff) { myArrayList <- createJavaObject("java.util.ArrayList", affinity = aff) myArrayList$add(5, affinity = aff) } result <- mclapply.j4r(1:1000, f) ## End(Not run)## Not run: f <- function(i, aff) { myArrayList <- createJavaObject("java.util.ArrayList", affinity = aff) myArrayList$add(5, affinity = aff) } result <- mclapply.j4r(1:1000, f) ## End(Not run)
The java.object instances that are included in this list are displayed up to a maximum number.
## S3 method for class 'java.list' print(x, ...)## S3 method for class 'java.list' print(x, ...)
x |
a java.list instance |
... |
additional parameters for consistent overriding |
The class name and the hashcode of the reference are displayed.
## S3 method for class 'java.object' print(x, ...)## S3 method for class 'java.object' print(x, ...)
x |
a java.object instance |
... |
additional parameters for consistent overriding |
This function sets a particular field, which can be either static or not. If the field is static, the source should be a valid class name.
setJavaField(source, fieldName, value, affinity = 1)setJavaField(source, fieldName, value, affinity = 1)
source |
this should be either a java.list instance or a single java.object instance for non-static methods or a string representing the Java class name in case of static method |
fieldName |
the name of the field to be set |
value |
the new value of the field |
affinity |
a parameter used by the mclapply.j4r function in case of multithreading. |
When the source is a java.object instance, this function can be substituted for the $ operator.
This is an option function that makes it possible to set the JAVA environment variable in R, if it is not already set. It first tests if the path ends with java or java.exe and if it is actually a file. Note that if an empty character is passed to this function, it resets the JAVA environment variable and J4R will then rely on the path to find java.exe.
setJavaPath(path)setJavaPath(path)
path |
the complete path to Java as in the example below. The file.path function should be used to define the path |
file.path
myPath <- file.path("C:","Program Files (x86)","Java", "jre1.8.0_221", "bin", "java.exe") # setJavaPath(myPath) ### not runmyPath <- file.path("C:","Program Files (x86)","Java", "jre1.8.0_221", "bin", "java.exe") # setJavaPath(myPath) ### not run
The level refers to the Java nomenclature: SEVERE, WARNING, INFO, FINE, FINER, and FINEST.
setLogLevel(level)setLogLevel(level)
level |
a String among these: SEVERE, WARNING, INFO, FINE, FINER, and FINEST (case sensitive) |
nothing
This environment contains the general settings of the package.
settingEnvsettingEnv
An object of class environment of length 2.
This function sets the value at the location given by the index parameter. It relies on the reflexive methods the Java class Array.
setValueInArray(object, value, index = NULL, affinity. = 1)setValueInArray(object, value, index = NULL, affinity. = 1)
object |
a java.object that represents an array |
value |
the value to be set |
index |
the index of the location at which the value is set. Note that in Java the first index is 0. If this argument is set to NULL, then it is assumed that the value is set to index 0. In case of vectorization, the values are set from 0 to length(value) - 1 if this argument is left to NULL. |
affinity. |
an optional parameter for multithreading (see the mclapply.j4r function) |
This function shuts down the client. If the server is private, it is also shut down.
shutdownClient()shutdownClient()
This function shuts down Java and the gateway server. THIS FUNCTION IS DEPRECATED. PLEASE USE shutdownClient instead
shutdownJava()shutdownJava()