Argument, passing a textfile

[Keshan Pillay]

Hey everyone! I have to make a postfix calculator, and I think i'm pretty sorted as to the code for it. However, something that confuses me is:

 
 
/*
 *=============================================================
 *PostfixCalc : Postfix Calculators
 *Evaluate postfix expressions
 *==============================================================
 */
 
public class PostfixCalc {
 
/** constructor
* @param infileName: the input filename
* Read input from the text file and process each line
*/
public PostfixCalc(String infileName) {
 
}
 
/** process method: Evaluate an expresion
* @param expression: the input expresion
* Evaluate the input expression and display the result
* You need to use Stack from textbook: StackInterface s
*/
public void process(String expression ) {
 
}
 
/** main method for PostfixCalc
 */
public static void main(String[] args) {
if ( args.length == 1) {
PostfixCalc c = new PostfixCalc(args[0]);
} else
System.out.println("Missing input filename");
}
}   

I use textpad to do my editing, compiling etc. I've been told I need to pass a textfile, as an argument? Or I'm just confused... How do I do this? I think its something to do with run parameters.

Many Thanks
Keshan Pillay

[Campbell Ritchie]

Difficult to be sure, but I think it might refer to a command line argument. You write

java PostfixCalc "1 2+ 3*"

The structure of your main method requires the "" otherwise it would only recognise 1. You cannot join the arguments together and maintain postfix nomenclature, otherwise it would read 12+3* or 123+4* which is ambiguous.

[Keshan Pillay]

Thanks for the reply! I got it sorted! turns out I had to make a file I/O method, because the calculations were in a text file, and then pass the textfile as an argument through the command prompt.