package unstar.server;

import java.io.File;
import java.io.FileNotFoundException;

/**
 * The main class for launching a server.
 */
public final class Launcher {

    /**
     * Hidden constructor.
     */
    private Launcher() {
    }

    /**
     * The main method, launches a server.
     * @param args  command line arguments
     */
    public static void main(final String[] args) {
        try {
            new Server(new File(args[0]), 2000, System.out).run();
        } catch (FileNotFoundException e) {
            System.err.println("File not found: " + e.getMessage());
            System.exit(-1);
        }
    }
}

@@ -398,60 +398,240 @@
     
-try %7B%0A            new Server(new File(args%5B0%5D), 2000
+if (args.length != 1) %7B%0A            System.err.println(%22error: select one file to serve%22);%0A            System.exit(-1);%0A        %7D%0A%0A        try %7B%0A            File in = new File(args%5B0%5D);%0A            new Server(in, Server.DEFAULT_PORT
 , Sy

Tweak the server launcher.