What is the use of System in read

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What is the use of System in read   in java  Please explain this

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System is a final class in java lang package  code sample from the source code of api  public final class System                  The  standard  input stream  This stream is already        open and ready to supply input data  Typically this stream        corresponds to keyboard input or another input source specified by        the host environment or user              public final static InputStream in   nullInputStream         read   is an abstract method of abstract class InputStream              Reads the next byte of data from the input stream  The value byte is        returned as an  lt code gt int lt  code gt  in the range  lt code gt 0 lt  code gt  to         lt code gt 255 lt  code gt   If no byte is available because the end of the stream        has been reached  the value  lt code gt -1 lt  code gt  is returned  This method        blocks until input data is available  the end of the stream is detected         or an exception is thrown                 lt p gt  A subclass must provide an implementation of this method                 return     the next byte of data  or  lt code gt -1 lt  code gt  if the end of the                    stream is reached          exception  IOException  if an I O error occurs              public abstract int read   throws IOException    In short from the api      Reads some number of bytes from the input stream and stores them into   the buffer array b  The number of bytes actually read is returned as   an integer  This method blocks until input data is available  end of   file is detected  or an exception is thrown    from InputStream html read

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May be this example will help you   import java io IOException   public class MainClass        public static void main String   args            int inChar          System out println  Enter a Character             try               inChar   System in read                System out print  You entered                 System out println inChar                     catch  IOException e               System out println  Error reading from user

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Two and a half years late is better than never  right   int System in read   reads the next byte of data from the input stream   But I am sure you already knew that  because it is trivial to look up   So  what you are probably asking is    Why is it declared to return an int when the documentation says that it reads a byte  and why does it appear to return garbage   I type  9   but it returns 57     It returns an int because besides all the possible values of a byte  it also needs to be able to return an extra value to indicate end-of-stream   So  it has to return a type which can express more values than a byte can   Note  They could have made it a short  but they opted for int instead  possibly as a tip of the hat of historical significance to C  whose getc   function also returns an int  but more importantly because short is a bit cumbersome to work with   the language offers no means of specifying a short literal  so you have to specify an int literal and cast it to short   plus on certain architectures int has better performance than short   It appears to return garbage because when you view a character as an integer  what you are looking at is the ASCII    value of that character   So  a  9  appears as a 57   But if you cast it to a character  you get  9   so all is well   Think of it this way  if you typed the character  9  it is nonsensical to expect System in read   to return the number 9  because then what number would you expect it to return if you had typed an  a   Obviously  characters must be mapped to numbers   ASCII    is a system of mapping characters to numbers   And in this system  character  9  maps to number 57  not number 9       Not necessarily ASCII  it may be some other encoding  like UTF-16  but in the vast majority of encodings  and certainly in all popular encodings  the first 127 values are the same as ASCII  And this includes all english alphanumeric characters and popular symbols

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This example should help  Along with the comments  of course      WARNING  MAN IS AN OVERUSED FREQUENT WORD IN THIS PARAGRAPH POST  Overall I recommend using the Scanner class since you can input large sentences  I m not entirely sure System in read has such aspects  If possible  please correct me   public class InputApp       Don t worry  passing in args in the main method as one of the arguments isn t required MAN      public static void main String   argumentalManWithAManDisorder           char inputManAger           System out println  Input Some Crap Man              try                 If you forget to cast char you will FAIL YOUR TASK MAN             inputManAger    char  System in read                System out print  You entererd     inputManAger     MAN                      catch Exception e               System out println  ELEMENTARY SCHOOL MAN

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It allows you to read from the standard input  mainly  the console   This SO question may helps you

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System in read   reads from the standard input   The standard input can be used to get input from user in a console environment but  as such user interface has no editing facilities  the interactive use of standard input is restricted to courses that teach programming   Most production use of standard input is in programs designed to work inside Unix command-line pipelines  In such programs the payload that the program is processing is coming from the standard input and the program s result gets written to the standard output  In that case the standard input is never written directly by the user  it is the redirected output of another program or the contents of a file   A typical pipeline looks like this     list files and directories ordered by increasing size du -s     sort -n   sort reads its data from the standard input  which is in fact the output of the du command  The sorted data is written to the standard output of sort  which ends up on the console by default  and can be easily redirected to a file or to another command   As such  the standard input is comparatively rarely used in Java

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import java io IOException   class ExamTest       public static void main String args    throws IOException          int sn System in read            System out println sn              If you want get char input you have to cast like this  char sn  char  System in read    The value byte is returned as int in the range 0 to 255  However  unlike in other languages    methods  System in read   reads only a byte at a time

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system in read   method reads a byte and returns as an integer but if you enter a no between 1 to 9  it will return 48  values because in ascii code table  ascii values of 1-9 are 48-57    hope   it will help

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Just to complement the accepted answer  you could also use System out read   like this   class Example       public static void main String args            throws java io IOException      This works  No need to use try        catch IOException ex                            System out println  Type a letter              char letter    char  System in read            System out println  You typed the letter     letter

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System in read   is a read input method for System in class which is  Standard Input file  or 0 in conventional OS

[java] What is the use of System.in.read()?

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