Exercise 11: Checking Arguments

This program checks that there are exactly two command line arguments, and then prints them out with commas in between.

Your task is to adapt it to test that there are exactly three arguments, and print them out.

// Check that two command line arguments have been given. class Check { public static void main(String[] args) { Check program = new Check(); if (args.length != 2) { System.err.println("Usage: java Check x y"); System.exit(1); } program.report(args[0], args[1]); } void report(String s1, String s2) { System.out.println("Args: " + s1 + ", " + s2); } }

You may wonder why the program uses System.err.println and System.exit, so here are explanations:

• Error Messages
• How to Exit After an Error

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