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Re: The greeting code in Java

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On 06/19/2011 03:15 PM, Saeed Amrollahi wrote:
> What is the Scanner? Why we use nextLine? What's the relation of
> such concepts with a simple greeting program.

java.util.Scanner is a very useful class for parsing simple textual 
protocols, that makes retrieval of words, lines, numbers, etc. very 
simple. In other words, it's very much like istream::operator<< except 
more explicit in what it is doing (does operator<<(string&) feed me a 
word or a line?); that Java did not have it until version 5 is a great 
shame.

> Why the code for writing "Hello, world" is in chapter 1, page 1
> of The Java Programming Language, but the code of greeting may be in
> Chapter 20!

Outputting ASCII is very simple, and "Hello, world" has become (for 
better or for worse) the standard introduction to programming. True I/O, 
one that takes into account the harsh vagaries of international text and 
the heaping mess that is character sets, is actually very difficult and 
very easy to get wrong. Reading from an input stream is actually 
logically difficult (what happens if you read from a closed stdin?); 
Java 1.0 actually got this mildly wrong, which is part of the reason why 
the APIs for particularly reading Strings is much more circuitous.

-- 
Beware of bugs in the above code; I have only proved it correct, not 
tried it. -- Donald E. Knuth

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The greeting code in Java Saeed Amrollahi <amrollahi.saeed@gmail.com> - 2011-06-19 06:05 -0700
  Re: The greeting code in Java rossum <rossum48@coldmail.com> - 2011-06-19 17:36 +0100
    Re: The greeting code in Java Saeed Amrollahi <amrollahi.saeed@gmail.com> - 2011-06-19 12:15 -0700
      Re: The greeting code in Java Martin Gregorie <martin@address-in-sig.invalid> - 2011-06-19 19:46 +0000
        Re: The greeting code in Java Saeed Amrollahi <amrollahi.saeed@gmail.com> - 2011-06-19 22:34 -0700
          Re: The greeting code in Java Jukka Lahtinen <jtfjdehf@hotmail.com.invalid> - 2011-06-23 11:43 +0300
        Re: The greeting code in Java Martin Gregorie <martin@address-in-sig.invalid> - 2011-06-20 10:13 +0000
          Re: The greeting code in Java Michael Wojcik <mwojcik@newsguy.com> - 2011-06-22 09:29 -0400
      Re: The greeting code in Java Joshua Cranmer <Pidgeot18@verizon.invalid> - 2011-06-19 16:00 -0400
      Re: The greeting code in Java Eric Sosman <esosman@ieee-dot-org.invalid> - 2011-06-19 16:05 -0400
        Re: The greeting code in Java Saeed Amrollahi <amrollahi.saeed@gmail.com> - 2011-06-19 22:40 -0700
      Re: The greeting code in Java rossum <rossum48@coldmail.com> - 2011-06-19 22:28 +0100
  Re: The greeting code in Java Roedy Green <see_website@mindprod.com.invalid> - 2011-06-19 21:14 -0700
  Re: The greeting code in Java Roedy Green <see_website@mindprod.com.invalid> - 2011-06-19 21:23 -0700
  Re: The greeting code in Java blmblm@myrealbox.com <blmblm.myrealbox@gmail.com> - 2011-06-20 19:20 +0000
    Re: The greeting code in Java Ney André de Mello Zunino <zunino@softplan.com.br> - 2011-06-22 15:55 -0300

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