Packages

  • package root
    Definition Classes
    root
  • package scala
    Definition Classes
    root
  • package util
    Definition Classes
    scala
  • object Using

    A utility for performing automatic resource management.

    A utility for performing automatic resource management. It can be used to perform an operation using resources, after which it releases the resources in reverse order of their creation.

    Usage

    There are multiple ways to automatically manage resources with Using. If you only need to manage a single resource, the apply method is easiest; it wraps the resource opening, operation, and resource releasing in a Try.

    Example:

    import java.io.{BufferedReader, FileReader}
import scala.util.{Try, Using}

val lines: Try[Seq[String]] =
  Using(new BufferedReader(new FileReader("file.txt"))) { reader =>
    Iterator.continually(reader.readLine()).takeWhile(_ != null).toSeq
  }

    If you need to manage multiple resources, Using.Manager should be used. It allows the managing of arbitrarily many resources, whose creation, use, and release are all wrapped in a Try.

    Example:

    import java.io.{BufferedReader, FileReader}
import scala.util.{Try, Using}

val lines: Try[Seq[String]] = Using.Manager { use =>
  val r1 = use(new BufferedReader(new FileReader("file1.txt")))
  val r2 = use(new BufferedReader(new FileReader("file2.txt")))
  val r3 = use(new BufferedReader(new FileReader("file3.txt")))
  val r4 = use(new BufferedReader(new FileReader("file4.txt")))

  // use your resources here
  def lines(reader: BufferedReader): Iterator[String] =
    Iterator.continually(reader.readLine()).takeWhile(_ != null)

  (lines(r1) ++ lines(r2) ++ lines(r3) ++ lines(r4)).toList
}

    If you wish to avoid wrapping management and operations in a Try, you can use Using.resource, which throws any exceptions that occur.

    Example:

    import java.io.{BufferedReader, FileReader}
import scala.util.Using

val lines: Seq[String] =
  Using.resource(new BufferedReader(new FileReader("file.txt"))) { reader =>
    Iterator.continually(reader.readLine()).takeWhile(_ != null).toSeq
  }

    Suppression Behavior

    If two exceptions are thrown (e.g., by an operation and closing a resource), one of them is re-thrown, and the other is added to it as a suppressed exception. If the two exceptions are of different 'severities' (see below), the one of a higher severity is re-thrown, and the one of a lower severity is added to it as a suppressed exception. If the two exceptions are of the same severity, the one thrown first is re-thrown, and the one thrown second is added to it as a suppressed exception. If an exception is a ControlThrowable, or if it does not support suppression (see Throwable's constructor with an enableSuppression parameter), an exception that would have been suppressed is instead discarded.

    Exceptions are ranked from highest to lowest severity as follows:

    • java.lang.VirtualMachineError
    • java.lang.LinkageError
    • java.lang.InterruptedException and java.lang.ThreadDeath
    • fatal exceptions, excluding scala.util.control.ControlThrowable
    • scala.util.control.ControlThrowable
    • all other exceptions

    When more than two exceptions are thrown, the first two are combined and re-thrown as described above, and each successive exception thrown is combined as it is thrown.

    Definition Classes
    util
  • Manager
  • Releasable

object Manager

Linear Supertypes
AnyRef, Any
Ordering
  1. Alphabetic
  2. By Inheritance
Inherited
  1. Manager
  2. AnyRef
  3. Any
  1. Hide All
  2. Show All
Visibility
  1. Public
  2. All

Value Members

  1. final def !=(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  2. final def ##(): Int
    Definition Classes
    AnyRef → Any
  3. final def ==(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  4. def apply[A](op: (Manager) ⇒ A): Try[A]

    Performs an operation using a Manager, then closes the Manager, releasing its resources (in reverse order of acquisition).

    Performs an operation using a Manager, then closes the Manager, releasing its resources (in reverse order of acquisition).

    Example:

    val lines = Using.Manager { use =>
  use(new BufferedReader(new FileReader("file.txt"))).lines()
}

    If using resources which require an implicit Manager as a parameter, this method should be invoked with an implicit modifier before the function parameter:

    Example:

    val lines = Using.Manager { implicit use =>
  new SafeFileReader("file.txt").lines()
}

    See the main doc for Using for full details of suppression behavior.

    A

    the return type of the operation

    op

    the operation to perform using the manager

    returns

    a Try containing an exception if one or more were thrown, or the result of the operation if no exceptions were thrown

  5. final def asInstanceOf[T0]: T0
    Definition Classes
    Any
  6. def clone(): AnyRef
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()
  7. final def eq(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  8. def equals(arg0: Any): Boolean
    Definition Classes
    AnyRef → Any
  9. def finalize(): Unit
    Attributes
    protected[lang]
    Definition Classes
    AnyRef
    Annotations
    @throws( classOf[java.lang.Throwable] )
  10. final def getClass(): Class[_]
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  11. def hashCode(): Int
    Definition Classes
    AnyRef → Any
    Annotations
    @native()
  12. final def isInstanceOf[T0]: Boolean
    Definition Classes
    Any
  13. final def ne(arg0: AnyRef): Boolean
    Definition Classes
    AnyRef
  14. final def notify(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  15. final def notifyAll(): Unit
    Definition Classes
    AnyRef
    Annotations
    @native()
  16. final def synchronized[T0](arg0: ⇒ T0): T0
    Definition Classes
    AnyRef
  17. def toString(): String
    Definition Classes
    AnyRef → Any
  18. final def wait(): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  19. final def wait(arg0: Long, arg1: Int): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... )
  20. final def wait(arg0: Long): Unit
    Definition Classes
    AnyRef
    Annotations
    @throws( ... ) @native()

Inherited from AnyRef

Inherited from Any

Ungrouped