Class IO

java.lang.Object
java.io.IO
public final class IO extends Object
IO is a preview API of the Java platform.
Programs can only use IO when preview features are enabled.
Preview features may be removed in a future release, or upgraded to permanent features of the Java platform.
A collection of static convenience methods that provide access to system console for implicitly declared classes.

Each of this class' methods throws IOError if the system console is null; otherwise, the effect is as if a similarly-named method had been called on that console.

Input and output from methods in this class use the character set of the system console as specified by Console.charset().

Since:
23

  • Method Summary

    Modifier and Type
    Method
    Description
    static void
    print(Object obj)
    Writes a string representation of the specified object to the system console and then flushes that console.
    static void
    println()
    Terminates the current line on the system console and then flushes that console.
    static void
    println(Object obj)
    Writes a string representation of the specified object to the system console, terminates the line and then flushes that console.
    static String
    readln()
    Reads a single line of text from the system console.
    static String
    readln(String prompt)
    Writes a prompt as if by calling print, then reads a single line of text from the system console.

    Methods declared in class java.lang.Object

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

  • Method Details

    • println

      public static void println(Object obj)
      Writes a string representation of the specified object to the system console, terminates the line and then flushes that console.

      The effect is as if println(obj)PREVIEW had been called on System.console().

      Parameters:
      obj - the object to print, may be null
      Throws:
      IOError - if System.console() returns null, or if an I/O error occurs

    • println

      public static void println()
      Terminates the current line on the system console and then flushes that console.

      The effect is as if println()PREVIEW had been called on System.console().

      Throws:
      IOError - if System.console() returns null, or if an I/O error occurs
      Since:
      24

    • print

      public static void print(Object obj)
      Writes a string representation of the specified object to the system console and then flushes that console.

      The effect is as if print(obj)PREVIEW had been called on System.console().

      Parameters:
      obj - the object to print, may be null
      Throws:
      IOError - if System.console() returns null, or if an I/O error occurs

    • readln

      public static String readln(String prompt)
      Writes a prompt as if by calling print, then reads a single line of text from the system console.

      The effect is as if readln(prompt)PREVIEW had been called on System.console().

      Parameters:
      prompt - the prompt string, may be null
      Returns:
      a string containing the line read from the system console, not including any line-termination characters. Returns null if an end of stream has been reached without having read any characters.
      Throws:
      IOError - if System.console() returns null, or if an I/O error occurs

    • readln

      public static String readln()
      Reads a single line of text from the system console.

      The effect is as if readln()PREVIEW had been called on System.console().

      Returns:
      a string containing the line read from the system console, not including any line-termination characters. Returns null if an end of stream has been reached without having read any characters.
      Throws:
      IOError - if System.console() returns null, or if an I/O error occurs
      Since:
      24