Scala example source code file (package.scala)

This example Scala source code file (package.scala) is included in my "Source Code Warehouse" project. The intent of this project is to help you more easily find Scala source code examples by using tags.

All credit for the original source code belongs to scala-lang.org; I'm just trying to make examples easier to find. (For my Scala work, see my Scala examples and tutorials.)

Scala tags/keywords

array, collection, indexedseq, int, nothing, runtime, shutdownhookthread, string, systemproperties, throwable, unit

The package.scala Scala example source code

/*                     __                                               *\
**     ________ ___   / /  ___     Scala API                            **
**    / __/ __// _ | / /  / _ |    (c) 2003-2013, LAMP/EPFL             **
**  __\ \/ /__/ __ |/ /__/ __ |    http://scala-lang.org/               **
** /____/\___/_/ |_/____/_/ | |                                         **
**                          |/                                          **
\*                                                                      */

package scala

import scala.collection.immutable
import scala.collection.JavaConverters._

/** The package object `scala.sys` contains methods for reading
 *  and altering core aspects of the virtual machine as well as the
 *  world outside of it.
 *
 *  @author Paul Phillips
 *  @version 2.9
 *  @since   2.9
 */
package object sys {
  /** Throw a new RuntimeException with the supplied message.
   *
   *  @return   Nothing.
   */
  def error(message: String): Nothing = throw new RuntimeException(message)

  /** Exit the JVM with the default status code.
   *
   *  @return   Nothing.
   */
  def exit(): Nothing = exit(0)

  /** Exit the JVM with the given status code.
   *
   *  @return   Nothing.
   */
  def exit(status: Int): Nothing = {
    java.lang.System.exit(status)
    throw new Throwable()
  }

  /** A convenience method to get the current Runtime instance.
   *
   *  @return   the result of `java.lang.Runtime.getRuntime()`
   */
  def runtime: Runtime = Runtime.getRuntime

  /** A bidirectional, mutable Map representing the current system Properties.
   *
   *  @return   a SystemProperties.
   *  @see      [[scala.sys.SystemProperties]]
   */
  def props: SystemProperties = new SystemProperties

  /** An immutable Map representing the current system environment.
   *
   *  @return   a Map containing the system environment variables.
   */
  def env: immutable.Map[String, String] = immutable.Map(System.getenv().asScala.toSeq: _*)

  /** Register a shutdown hook to be run when the VM exits.
   *  The newly created thread is marked as a daemon so it will not
   *  interfere with VM shutdown.  The hook is automatically registered:
   *  the returned value can be ignored, but is available in case the
   *  Thread requires further modification.  It can also be unregistered
   *  by calling ShutdownHookThread#remove().
   *
   *  Note that shutdown hooks are NOT guaranteed to be run.
   *
   *  @param    body  the body of code to run at shutdown
   *  @return   the   Thread which will run the shutdown hook.
   */
  def addShutdownHook(body: => Unit): ShutdownHookThread = ShutdownHookThread(body)

  /** Returns all active thread in the current thread's thread group and subgroups.
   *
   *  @return   an IndexedSeq containing the threads.
   */
  def allThreads(): IndexedSeq[Thread] = {
    val num    = Thread.activeCount()
    val tarray = new Array[Thread](num)
    val got    = Thread.enumerate(tarray)

    tarray take got
  }
}