## Class RJavaClassLoader

- java.lang.Object
- - java.lang.ClassLoader
  - - java.security.SecureClassLoader
    - - java.net.URLClassLoader
      - - RJavaClassLoader

- All Implemented Interfaces:
    java.io.Closeable, java.lang.AutoCloseable

      public class RJavaClassLoader
      extends java.net.URLClassLoader

  Class loader used internally by rJava The class manages the class paths and the native libraries (jri, ...)

- - ### Field Summary

    Fields
    Modifier and Type | Field and Description
    --- | ---
    `static RJavaClassLoader` | `primaryLoader` singleton
    `boolean` | `useSystem` Should the system class loader be used to resolve classes as well as this class loader
    `static boolean` | `verbose` Print debug messages if is set to `true`

  - ### Constructor Summary

    Constructors
    Constructor and Description
    `RJavaClassLoader(java.lang.String path, java.lang.String libpath)` Constructor.

  - ### Method Summary

    Methods
    Modifier and Type | Method and Description
    --- | ---
    `void` | `addClassPath(java.lang.String cp)` adds an entry to the class path
    `void` | `addClassPath(java.lang.String[] cp)` adds several entries to the class path
    `void` | `addRLibrary(java.lang.String name, java.lang.String path)` add a library to path mapping for a native library
    `void` | `bootClass(java.lang.String cName, java.lang.String mName, java.lang.String[] args)` Boots the specified method of the specified class
    `protected java.lang.Class` | `findClass(java.lang.String name)`
    `protected java.lang.String` | `findLibrary(java.lang.String name)`
    `java.net.URL` | `findResource(java.lang.String name)`
    `java.lang.String[]` | `getClassPath()`
    `static RJavaClassLoader` | `getPrimaryLoader()` Returns the singleton instance of RJavaClassLoader

    `static void`

    `main(java.lang.String[] args)`
    main method This uses the system properties: `rjava.path` : path of the rJava package `rjava.lib` : lib sub directory of the rJava package `main.class` : main class to "boot", assumes Main if not specified `rjava.class.path` : set of paths to populate the initiate the class path and boots the "main" method of the specified `main.class`, passing the args down to the booted class This makes sure R and rJava are known by the class loader

    `static void` | `setDebug(int level)` Set the debug level.
    `static byte[]` | `toByte(java.lang.Object object)` Serialize an object to a byte array.
    `java.lang.Object` | `toObject(byte[] byteArray)` Deserialize an object from a byte array.
    `static java.lang.Object` | `toObjectPL(byte[] byteArray)` converts the byte array into an Object using the primary RJavaClassLoader
    `static java.lang.String` | `u2w(java.lang.String fn)` Utility to convert paths for windows.

    - ### Methods inherited from class java.net.URLClassLoader

      `addURL, close, definePackage, findResources, getPermissions, getResourceAsStream, getURLs, newInstance, newInstance`

    - ### Methods inherited from class java.security.SecureClassLoader

      `defineClass, defineClass`

    - ### Methods inherited from class java.lang.ClassLoader

      `clearAssertionStatus, defineClass, defineClass, defineClass, defineClass, definePackage, findLoadedClass, findSystemClass, getClassLoadingLock, getPackage, getPackages, getParent, getResource, getResources, getSystemClassLoader, getSystemResource, getSystemResourceAsStream, getSystemResources, loadClass, loadClass, registerAsParallelCapable, resolveClass, setClassAssertionStatus, setDefaultAssertionStatus, setPackageAssertionStatus, setSigners`

    - ### Methods inherited from class java.lang.Object

      `clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait`

- - ### Field Detail

    - #### primaryLoader

          public static RJavaClassLoader primaryLoader

      singleton

    - #### verbose

          public static boolean verbose

      Print debug messages if is set to `true`

    - #### useSystem

          public boolean useSystem

      Should the system class loader be used to resolve classes as well as this class loader

  - ### Constructor Detail

    - #### RJavaClassLoader

          public RJavaClassLoader(java.lang.String path,
                          java.lang.String libpath)

      Constructor. The first time an RJavaClassLoader is created, it is cached as the primary loader.
      Parameters:
        `path` - path of the rJava package
        `libpath` - lib sub directory of the rJava package

  - ### Method Detail

    - #### getPrimaryLoader

          public static RJavaClassLoader getPrimaryLoader()

      Returns the singleton instance of RJavaClassLoader

    - #### findClass

          protected java.lang.Class findClass(java.lang.String name)
                                       throws java.lang.ClassNotFoundException

      Overrides:
        `findClass` in class `java.net.URLClassLoader`
      Throws:
        `java.lang.ClassNotFoundException`

    - #### findResource

          public java.net.URL findResource(java.lang.String name)

      Overrides:
        `findResource` in class `java.net.URLClassLoader`

    - #### addRLibrary

          public void addRLibrary(java.lang.String name,
                         java.lang.String path)

      add a library to path mapping for a native library

    - #### addClassPath

          public void addClassPath(java.lang.String cp)

      adds an entry to the class path

    - #### addClassPath

          public void addClassPath(java.lang.String[] cp)

      adds several entries to the class path

    - #### getClassPath

          public java.lang.String[] getClassPath()

      Returns:
        the array of class paths used by this class loader

    - #### findLibrary

          protected java.lang.String findLibrary(java.lang.String name)

      Overrides:
        `findLibrary` in class `java.lang.ClassLoader`

    - #### bootClass

          public void bootClass(java.lang.String cName,
                       java.lang.String mName,
                       java.lang.String[] args)
                         throws java.lang.IllegalAccessException,
                                java.lang.reflect.InvocationTargetException,
                                java.lang.NoSuchMethodException,
                                java.lang.ClassNotFoundException

      Boots the specified method of the specified class
      Parameters:
        `cName` - class to boot
        `mName` - method to boot (typically main). The method must take a String[] as parameter
        `args` - arguments to pass to the method
      Throws:
        `java.lang.IllegalAccessException`
        `java.lang.reflect.InvocationTargetException`
        `java.lang.NoSuchMethodException`
        `java.lang.ClassNotFoundException`

    - #### setDebug

          public static void setDebug(int level)

      Set the debug level. At the moment, there is only verbose (level > 0) or quiet
      Parameters:
        `level` - debug level. verbose (>0), quiet otherwise

    - #### u2w

          public static java.lang.String u2w(java.lang.String fn)

      Utility to convert paths for windows. Converts / to the path separator in use
      Parameters:
        `fn` - file name

    - #### main

          public static void main(java.lang.String[] args)

      main method

      This uses the system properties:

      - `rjava.path` : path of the rJava package
      - `rjava.lib` : lib sub directory of the rJava package
      - `main.class` : main class to "boot", assumes Main if not specified
      - `rjava.class.path` : set of paths to populate the initiate the class path

      and boots the "main" method of the specified `main.class`, passing the args down to the booted class

      This makes sure R and rJava are known by the class loader

    - #### toByte

          public static byte[] toByte(java.lang.Object object)
                               throws java.lang.Exception

      Serialize an object to a byte array. (code by CB)
      Parameters:
        `object` - object to serialize
      Returns:
        byte array that represents the object
      Throws:
        `java.lang.Exception`

    - #### toObject

          public java.lang.Object toObject(byte[] byteArray)
                                    throws java.lang.Exception

      Deserialize an object from a byte array. (code by CB)
      Parameters:
        `byteArray` -
      Returns:
        the object that is represented by the byte array
      Throws:
        `java.lang.Exception`

    - #### toObjectPL

          public static java.lang.Object toObjectPL(byte[] byteArray)
                                             throws java.lang.Exception

      converts the byte array into an Object using the primary RJavaClassLoader
      Throws:
        `java.lang.Exception`