Object scala.Console

object Console extends DeprecatedConsole with AnsiColor

Implements functionality for printing Scala values on the terminal. For reading values use StdIn. Also defines constants for marking up text on ANSI terminals.

Console Output

Use the print methods to output text.

scala> Console.printf(
  "Today the outside temperature is a balmy %.1f°C. %<.1f°C beats the previous record of %.1f°C.\n",
  -137.0,
  -135.05)
Today the outside temperature is a balmy -137.0°C. -137.0°C beats the previous record of -135.1°C.

ANSI escape codes

Use the ANSI escape codes for colorizing console output either to STDOUT or STDERR.

import Console.{GREEN, RED, RESET, YELLOW_B, UNDERLINED}

object PrimeTest {

  def isPrime(): Unit = {

    val candidate = io.StdIn.readInt().ensuring(_ > 1)

    val prime = (2 to candidate - 1).forall(candidate % _ != 0)

    if (prime)
      Console.println(s"${RESET}${GREEN}yes${RESET}")
    else
      Console.err.println(s"${RESET}${YELLOW_B}${RED}${UNDERLINED}NO!${RESET}")
  }

  def main(args: Array[String]): Unit = isPrime()

}

$ scala PrimeTest

1234567891

yes

$ scala PrimeTest

56474

NO!

IO redefinition

Use IO redefinition to temporarily swap in a different set of input and/or output streams. In this example the stream based method above is wrapped into a function.

import java.io.{ByteArrayOutputStream, StringReader}

object FunctionalPrimeTest {

  def isPrime(candidate: Int): Boolean = {

    val input = new StringReader(s"$candidate\n")
    val outCapture = new ByteArrayOutputStream
    val errCapture = new ByteArrayOutputStream

    Console.withIn(input) {
      Console.withOut(outCapture) {
        Console.withErr(errCapture) {
          PrimeTest.isPrime()
        }
      }
    }

    if (outCapture.toByteArray.nonEmpty) // "yes"
      true
    else if (errCapture.toByteArray.nonEmpty) // "NO!"
      false
    else throw new IllegalArgumentException(candidate.toString)
  }

  def main(args: Array[String]): Unit = {
    val primes = (2 to 50) filter (isPrime)
    println(s"First primes: $primes")
  }

}

$ scala FunctionalPrimeTest

First primes: Vector(2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47)

Source: Console.scala
Since: 1.0

Linear Supertypes

Value Members

final def !=(arg0: Any): Boolean

Test two objects for inequality.

returns: true if !(this == that), false otherwise.

Definition Classes: AnyRef → Any

final def ##(): Int

Equivalent to x.hashCode except for boxed numeric types and null. For numerics, it returns a hash value which is consistent with value equality: if two value type instances compare as true, then ## will produce the same hash value for each of them. For null returns a hashcode where null.hashCode throws a NullPointerException.

returns: a hash value consistent with ==

Definition Classes: AnyRef → Any

final def ==(arg0: Any): Boolean

The expression x == that is equivalent to if (x eq null) that eq null else x.equals(that).

returns: true if the receiver object is equivalent to the argument; false otherwise.

Definition Classes: AnyRef → Any

final val BLACK: String("\u001B[30m")

Foreground color for ANSI black

Definition Classes: AnsiColor

final val BLACK_B: String("\u001B[40m")

Background color for ANSI black

Definition Classes: AnsiColor

final val BLINK: String("\u001B[5m")

ANSI blink

Definition Classes: AnsiColor

final val BLUE: String("\u001B[34m")

Foreground color for ANSI blue

Definition Classes: AnsiColor

final val BLUE_B: String("\u001B[44m")

Background color for ANSI blue

Definition Classes: AnsiColor

final val BOLD: String("\u001B[1m")

ANSI bold

Definition Classes: AnsiColor

final val CYAN: String("\u001B[36m")

Foreground color for ANSI cyan

Definition Classes: AnsiColor

final val CYAN_B: String("\u001B[46m")

Background color for ANSI cyan

Definition Classes: AnsiColor

final val GREEN: String("\u001B[32m")

Foreground color for ANSI green

Definition Classes: AnsiColor

final val GREEN_B: String("\u001B[42m")

Background color for ANSI green

Definition Classes: AnsiColor

final val INVISIBLE: String("\u001B[8m")

ANSI invisible

Definition Classes: AnsiColor

final val MAGENTA: String("\u001B[35m")

Foreground color for ANSI magenta

Definition Classes: AnsiColor

final val MAGENTA_B: String("\u001B[45m")

Background color for ANSI magenta

Definition Classes: AnsiColor

final val RED: String("\u001B[31m")

Foreground color for ANSI red

Definition Classes: AnsiColor

final val RED_B: String("\u001B[41m")

Background color for ANSI red

Definition Classes: AnsiColor

final val RESET: String("\u001B[0m")

Reset ANSI styles

Definition Classes: AnsiColor

final val REVERSED: String("\u001B[7m")

ANSI reversed

Definition Classes: AnsiColor

final val UNDERLINED: String("\u001B[4m")

ANSI underlines

Definition Classes: AnsiColor

final val WHITE: String("\u001B[37m")

Foreground color for ANSI white

Definition Classes: AnsiColor

final val WHITE_B: String("\u001B[47m")

Background color for ANSI white

Definition Classes: AnsiColor

final val YELLOW: String("\u001B[33m")

Foreground color for ANSI yellow

Definition Classes: AnsiColor

final val YELLOW_B: String("\u001B[43m")

Background color for ANSI yellow

Definition Classes: AnsiColor

final def asInstanceOf[T0]: T0

Cast the receiver object to be of type T0.

Note that the success of a cast at runtime is modulo Scala's erasure semantics. Therefore the expression 1.asInstanceOf[String] will throw a ClassCastException at runtime, while the expression List(1).asInstanceOf[List[String]] will not. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the requested type.

returns: the receiver object.

Definition Classes: Any
Exceptions thrown: ClassCastException if the receiver object is not an instance of the erasure of type T0.

def clone(): AnyRef

Create a copy of the receiver object.

The default implementation of the clone method is platform dependent.

returns: a copy of the receiver object.

Attributes: protected[lang]
Definition Classes: AnyRef
Annotations: @throws( ... ) @native()
Note: not specified by SLS as a member of AnyRef

final def eq(arg0: AnyRef): Boolean

Tests whether the argument (that) is a reference to the receiver object (this).

The eq method implements an equivalence relation on non-null instances of AnyRef, and has three additional properties:

x

y

AnyRef

x.eq(y)

true

false

x

AnyRef

x.eq(null)

null.eq(x)

false

null.eq(null)

true

When overriding the equals or hashCode methods, it is important to ensure that their behavior is consistent with reference equality. Therefore, if two objects are references to each other (o1 eq o2), they should be equal to each other (o1 == o2) and they should hash to the same value (o1.hashCode == o2.hashCode).

returns: true if the argument is a reference to the receiver object; false otherwise.

Definition Classes: AnyRef

def equals(arg0: Any): Boolean

The equality method for reference types. Default implementation delegates to eq.

def err: PrintStream

def finalize(): Unit

Called by the garbage collector on the receiver object when there are no more references to the object.

The details of when and if the finalize method is invoked, as well as the interaction between finalize and non-local returns and exceptions, are all platform dependent.

Attributes: protected[lang]
Definition Classes: AnyRef
Annotations: @throws( classOf[java.lang.Throwable] )
Note: not specified by SLS as a member of AnyRef

def flush(): Unit

Flushes the output stream. This function is required when partial output (i.e. output not terminated by a newline character) has to be made visible on the terminal.

final def getClass(): Class[_]

Returns the runtime class representation of the object.

returns: a class object corresponding to the runtime type of the receiver.

Definition Classes: AnyRef → Any
Annotations: @native()

def hashCode(): Int

The hashCode method for reference types. See hashCode in scala.Any.

returns: the hash code value for this object.

Definition Classes: AnyRef → Any
Annotations: @native()

def in: BufferedReader

final def isInstanceOf[T0]: Boolean

Test whether the dynamic type of the receiver object is T0.

Note that the result of the test is modulo Scala's erasure semantics. Therefore the expression 1.isInstanceOf[String] will return false, while the expression List(1).isInstanceOf[List[String]] will return true. In the latter example, because the type argument is erased as part of compilation it is not possible to check whether the contents of the list are of the specified type.

returns: true if the receiver object is an instance of erasure of type T0; false otherwise.

Definition Classes: Any

final def ne(arg0: AnyRef): Boolean

Equivalent to !(this eq that).

returns: true if the argument is not a reference to the receiver object; false otherwise.

Definition Classes: AnyRef

final def notify(): Unit

Wakes up a single thread that is waiting on the receiver object's monitor.

Definition Classes: AnyRef
Annotations: @native()
Note: not specified by SLS as a member of AnyRef

final def notifyAll(): Unit

Wakes up all threads that are waiting on the receiver object's monitor.

Definition Classes: AnyRef
Annotations: @native()
Note: not specified by SLS as a member of AnyRef

def out: PrintStream

def print(obj: Any): Unit

Prints an object to out using its toString method.

obj: the object to print; may be null.

def printf(text: String, args: Any*): Unit

Prints its arguments as a formatted string to the default output, based on a string pattern (in a fashion similar to printf in C).

The interpretation of the formatting patterns is described in java.util.Formatter.

text: the pattern for formatting the arguments.
args: the arguments used to instantiating the pattern.

Exceptions thrown: java.lang.IllegalArgumentException if there was a problem with the format string or arguments

def println(x: Any): Unit

Prints out an object to the default output, followed by a newline character.

x: the object to print.

def println(): Unit

def setErrDirect(err: PrintStream): Unit

Attributes: protected
Definition Classes: Console → DeprecatedConsole

def setInDirect(in: BufferedReader): Unit

Attributes: protected
Definition Classes: Console → DeprecatedConsole

def setOutDirect(out: PrintStream): Unit

Internal usage only.

Attributes: protected
Definition Classes: Console → DeprecatedConsole

final def synchronized[T0](arg0: ⇒ T0): T0

Definition Classes: AnyRef

def toString(): String

Creates a String representation of this object. The default representation is platform dependent. On the java platform it is the concatenation of the class name, "@", and the object's hashcode in hexadecimal.

returns: a String representation of the object.

Definition Classes: AnyRef → Any

final def wait(): Unit

Definition Classes: AnyRef
Annotations: @throws( ... )

final def wait(arg0: Long, arg1: Int): Unit

Definition Classes: AnyRef
Annotations: @throws( ... )

final def wait(arg0: Long): Unit

Definition Classes: AnyRef
Annotations: @throws( ... ) @native()

def withErr[T](err: OutputStream)(thunk: ⇒ T): T

Sets the default error stream for the duration of execution of one thunk.

err: the new error stream.
thunk: the code to execute with the new error stream active
returns: the results of thunk

See also: withErr[T](err:PrintStream)(thunk: =>T)

def withErr[T](err: PrintStream)(thunk: ⇒ T): T

Set the default error stream for the duration of execution of one thunk.

err: the new error stream.
thunk: the code to execute with the new error stream active
returns: the results of thunk

See also: withErr[T](err:OutputStream)(thunk: =>T)

def withIn[T](in: InputStream)(thunk: ⇒ T): T

Sets the default input stream for the duration of execution of one thunk.

in: the new input stream.
thunk: the code to execute with the new input stream active
returns: the results of thunk

See also: withIn[T](reader:Reader)(thunk: =>T)

def withIn[T](reader: Reader)(thunk: ⇒ T): T

Sets the default input stream for the duration of execution of one thunk.

thunk: the code to execute with the new input stream active
returns: the results of thunk

See also: withIn[T](in:InputStream)(thunk: =>T)

def withOut[T](out: OutputStream)(thunk: ⇒ T): T

Sets the default output stream for the duration of execution of one thunk.

out: the new output stream.
thunk: the code to execute with the new output stream active
returns: the results of thunk

See also: withOut[T](out:PrintStream)(thunk: => T)

def withOut[T](out: PrintStream)(thunk: ⇒ T): T

Sets the default output stream for the duration of execution of one thunk.

out: the new output stream.
thunk: the code to execute with the new output stream active
returns: the results of thunk

See also: withOut[T](out:OutputStream)(thunk: => T)

© 2002-2019 EPFL, with contributions from Lightbend.
Licensed under the Apache License, Version 2.0.
https://www.scala-lang.org/api/2.12.9/scala/Console$.html