How does the args[] in the main work?

The args array is a parameter of the main method, as you probably know what calls the main method is Java itself, when it does so it passes in a string array based on the arguments that is provided when the program is run.

If you ran the program from the command line like this for example:

java Main Hello World

Then all the words typed after Main would be treated as arguments. So args[0] would be set to "Hello" and args[1] would be set to "World".

So the program gets the value of args[0] and args[1] from whatever is running the code. In this case that is the Treehouse code checker, which is likely programmed to pass in two specific names as arguments.

The method also includes a check that there is enough arguments and an error messsage if there is not:

if (args.length < 2) {
    System.out.println("Usage: java Main <first name> <last name>");
    System.err.println("<first name> and <last name> are required");
    System.exit(1);
}

Arguments were also discussed in the Arrays and Command Line Arguments video that appears earlier in this section.

Thanks! that makes sense. So for the greater picture: If i fil in a form on a webpage, could that be the args for the main.java?