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Thread: detailed description

  1. #1
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    Default detailed description

    How does System.out.println() works?


  2. #2
    Super Moderator helloworld922's Avatar
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    Default Re: detailed description

    Are you talking about the underlying implementation? Or just the semantics of the calling syntax? if it's the latter, see How Does System.out.println work in Java

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    Crazy Cat Lady KevinWorkman's Avatar
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    Default Re: detailed description

    Quote Originally Posted by helloworld922 View Post
    Are you talking about the underlying implementation? Or just the semantics of the calling syntax? if it's the latter, see How Does System.out.println work in Java
    Interesting link. I'm not sure I really agree with how they described it though. One thing really stuck out to me:

    Now, how do we categorize 'out'? Since println() is clearly a method, and its called using 'out', then we know that 'out' can not possibly be a method because it doesn't make sense to have one method invoke another method with the dot operator in Java. This means 'out' must be a variable.
    Sure, out is a static variable. But it has nothing to do with the dot operator, or being unable to call methods on whatever is returned from another method. The biggest sign that it's a variable and not a method is simply the lack of () after it.

    To say that it doesn't make sense to have one method invoke another is simply wrong. Actually, this happens all the time. Here are a few examples:

    JTable table = new JTable();
    String tableValue = table.getModel().getValueAt(0,0).toString();
    String parsedValue = tableValue.subString(0, 5).toUpperCase().replaceAll("1", "ONE");

    I'm pretty skeptical about that programming interview site in general. I would say your first step to figuring out how System.out.println() works is to trace through the API:

    System
    .out
    .println()
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    Super Moderator helloworld922's Avatar
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    Default Re: detailed description

    Quote Originally Posted by KevinWorkman View Post
    Interesting link. I'm not sure I really agree with how they described it though. One thing really stuck out to me:



    Sure, out is a static variable. But it has nothing to do with the dot operator, or being unable to call methods on whatever is returned from another method. The biggest sign that it's a variable and not a method is simply the lack of () after it.

    To say that it doesn't make sense to have one method invoke another is simply wrong. Actually, this happens all the time. Here are a few examples:

    JTable table = new JTable();
    String tableValue = table.getModel().getValueAt(0,0).toString();
    String parsedValue = tableValue.subString(0, 5).toUpperCase().replaceAll("1", "ONE");

    I'm pretty skeptical about that programming interview site in general. I would say your first step to figuring out how System.out.println() works is to trace through the API:

    System
    .out
    .println()
    I just popped the question into google and linked one of the results. My bad for not thoroughly examining the contents

    Thanks for the corrections/clarifications.
    Last edited by helloworld922; April 8th, 2011 at 12:05 AM.

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    Default Re: detailed description

    Quote Originally Posted by helloworld922 View Post


    Hi guys, thanks for the correction of the mistake - I am the owner of the site, and I have updated the page to reflect the correct information.

    Of course, my opinion is biased but I think Software interview questions is a great site - and have received much input agreeing with that claim. I do try my best to clean up any errors - and I really appreciate you pointing this one out. If you see anything else please let me know.

    Thanks!