CODEWITHSUNDEEP
javaeclipse
PKlumpp
PKlumpp

Reputation: 5233

Consoles in Java

I do have some serious troubles understanding the console in java. I am running Eclipse, and I wanted to write a small program which prompts a few text messages to the console and receives a few strings as input arguments from it. Problem is: When I run my program, it opens the command line window properly, but my outputs are only printed on the Eclipse-Console. In some way, I do understand why this is the case. The Command Line Windows expects commands, and not just some kind of a string or something. But how do i manage to output my Strings into the Command Line Window and read Strings from it, and not just commands. Or am I doing it the wrong way? Do I have to open another "Console" where all my messages will be prompted and from which i can read strings a user wrote?

This is the code i use to open a command line window on start:

    public static void main(String args[]) throws Exception {
    Process process = new ProcessBuilder(new String[] { "cmd", "/C",
            "start", "cmd" }).start();
    System.out.println(process.waitFor());

Edit: I did still not manage to get this to working. Somehow, when I compiled the program, and I run it, it properly opens a command window, but no messages are posted there. Seems like "System.out.println("xxx") does not have any effect on this window.

Upvotes: 1

Views: 197

Answers (2)

user3027681
user3027681

Reputation: 53

You might want to read through this page:

http://pages.cs.wisc.edu/~hasti/cs368/JavaTutorial/NOTES/JavaIO_Scanner.html

Basically what you need to is create the input stream, tell the user to input something, and then get the input. E.g.

private static Scanner newScanner = new Scanner(System.in);

public static void main(String[] args) {

    System.out.println("Put your input here: ");

    String inputValue = newScanner.nextLine(); 

    System.out.println(inputValue);

}

Just remember to import the scanner library!

Upvotes: 0

Miquel
Miquel

Reputation: 15675

There's no "console" specified by your program, but an stdin, stdout and stderr for input, output and error output. When you run your program from windows, these streams are bound to a command window, and if you run it in eclipse, they will be associated to the eclipse console. To give a more obscure example, ff you were running it through ssh, the streams would be associated to ssh, and ssh associated to your command window, and so on.

So, you're not doing anything wrong, you just need to run the program from the command line if you want stdout and stdin to come from that command window.

How do you open a command window, by the way?

Upvotes: 2

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