File Redirection in java

Question

I have a program that uses file redirection to read using System.in. Is there anyway to throw an exception if the file redirection isn't in the command line
Here is my code:
public static void main(String[] args) throws IOException {
        Scanner sc = new Scanner(System.in);
        InetAddress addr = InetAddress.getLocalHost();
        String msgReply, hostName, fromAddress, toAddress, temp;
        String data = "";
        int portNum = 25;
        hostName = args[0];
        fromAddress = args[1];
        toAddress = args[2];
        Socket theSocket = new Socket(hostName, portNum);
        BufferedReader in = new BufferedReader(new InputStreamReader(theSocket.getInputStream()));
        OutputStreamWriter out = new OutputStreamWriter(theSocket.getOutputStream());
        BufferedWriter wrt = new BufferedWriter(out);
        msgReply = in.readLine();
        Main.msgCheck(msgReply);
        System.out.println(msgReply);
        wrt.write("HELO " + addr.getHostAddress() + "\r\n");
        wrt.flush();
        msgReply = in.readLine();
        Main.msgCheck(msgReply);
        System.out.println(msgReply);
        wrt.write("MAIL FROM:" + fromAddress + "\r\n");
        wrt.flush();
        msgReply = in.readLine();
        Main.msgCheck(msgReply);
        System.out.println(msgReply);
        wrt.write("RCPT TO:" + toAddress + "\r\n");
        wrt.flush();
        msgReply = in.readLine();
        Main.msgCheck(msgReply);
        System.out.println(msgReply);
        wrt.write("DATA \r\n");
        wrt.flush();
        in.readLine();
            while (sc.hasNext()) {
                temp = sc.nextLine();
                if (temp.startsWith(".")) {
                    data += "." + temp + "\r\n";
                } else {
                    data += temp + "\r\n";
        wrt.write(data + "\r\n");
        wrt.flush();
        wrt.write(".\r\n");
        wrt.flush();
        msgReply = in.readLine();
        Main.msgCheck(msgReply);
        System.out.println(msgReply);
        System.out.println(data);
        wrt.write("QUIT \r\n");
        wrt.flush();
        msgReply = in.readLine();
        Main.msgCheck(msgReply);
        System.out.println(msgReply);
        System.exit(0);
    public static void msgCheck(String msgReply) {
        if (msgReply.startsWith("5") || msgReply.startsWith("4")) {
            System.exit(0);
}  //end Main classCommand line should look like:
java Main smtp.google.com [email protected] [email protected] <test.txt
Is there anyway to check for:
java Main smtp.google.com [email protected] [email protected]
Thanks

Answer 1

No. And why should you care about that anyway? If I don't redirect from the file, that gives me the opportunity to type in the message I want to send, instead of having to put it into a file beforehand. Or I could write a program that produces the message and pipe its output into your program:
java PoliteMessageGenerator | java Main smtp.google.com [email protected] [email protected]
No, that's a feature and not a bug.