command line arguments

[evermore]

srry if this isn't a newbie question, in that case i posted in wrong section


i understand how to work the arguement passed in when u do java myjavaapp



my question is how can i get it to read a text file


example

i have text file

// superman.txt


one two three four five


// end of text file

how can i pass the whole txt file into my command line

java myjavaapp < superman.txt

this doesn't work, i just get output as <

when i do System.out.print(args[0]);

is this possible, i am successful in passing just regular string
but i want to pass a whole .txt



and i am aware i can do this with bufferReader etc......

but i dont' want that =)


thx for your thoughts

[Fubarable]

Perhaps this is what you want: The ins and outs of standard input/output - JavaWorld

Thank God for Google!

[gcalvin]

Lines from a text file aren't passed as arguments to a program when you use < or > or | -- those operators redirect the standard input and standard output streams. Here's a very rough example:

import java.util.Scanner;

public class StdinReader {

	/**
	 * @param args
	 */
	public static void main(String[] args) {
		Scanner stdin = new Scanner(System.in);
		while (stdin.hasNextLine()) {
			System.out.println("We received >>" + stdin.nextLine() + "<<");
		}
	}

}

That program could be run like so:

host:~ user$ java StdinReader <superman.txt
We received >><<
We received >><<
We received >>one two three four five<<
We received >><<
We received >><<
We received >><<

Hope that helps.

-Gary-

[evermore]

thx for reply but i do not want to do it this way

i know how to use system.in
buffer reader
readLine ..... etcc...

i was wondering if it's possible to pass .txt file as argument to java's main method

and print it off


public class Test{

public static void main(String[] args)
{

for ( int i = 0; i < args.length() ; i++)
{
System.out.println(args[i]);
}
}
}

[gcalvin]

Depending on the operating system you might be able to do what you want from the command shell:

host:~ user$ cat superman.txt | xargs java YourClass

That won't work for Windows unless you install the GNU findutils. findutils - GNU Project - Free Software Foundation (FSF)

Otherwise you don't get the file contents, just the file name. Of course you could write another helper program to read the file and pass arguments to your main().

-Gary-

[gcalvin]

And I just wanted to point out that none of this is about Java, really. It's really more about how operating systems work.

-Gary-