Question

I am not sure how you are supposed to read in from system input from a Java file.

I want to be able to call java myProg < file

Where file is what I want to be read in as a string and given to myProg in the main method.

Any suggestions?

Answer 1

You can use System.in to read from the standard input. It works just like entering it from a keyboard. The OS handles going from file to standard input.

import java.util.Scanner;
class MyProg {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        System.out.println("Printing the file passed in:");
        while(sc.hasNextLine()) System.out.println(sc.nextLine());
    }
}