使用文件输入运行Java程序

Question

I am writing a program that reads the input from a file and then prints it to the screen. When I run it without taking the input from the file, it works perfectly fine. However, every time I try to run it from the file it gives me an "Exception in thread "main" java.util.NoSuchElementException: No line found at" error that occurs every place the input is suppose to be read. I have no idea what is going on.

This program is suppose to take the input from the user, create a Photo object, and then print the information to the screen. Everything runs fine when I am entering the information manually but when I try to use java PhotoTest < test.dat to get the input for a file it gives this error message:
Exception in thread "main" java.util.NoSuchElementException: No line found
at java.util.Scanner.nextLine(Scanner.java:1516)
at PhotoTest.readPhoto(PhotoTest.java:31)
at PhotoTest.main(PhotoTest.java:74)

My code that has input:

private static Photo readPhoto(Scanner scanner) throws ParseException
{
    Date dateTaken;

    Scanner scan = new Scanner(System.in);

    String subject = scan.nextLine();
    subject = subject.trim();

    String location = scan.nextLine();
    location = location.trim();

    String date = scan.nextLine();
    date = date.trim();
        if (date.equals("")){ //if the date is empty it is set to null
            dateTaken = null;
            }
        else { //if a date is entered, it is then parsed
            DateFormat df = DateFormat.getDateInstance(DateFormat.SHORT);
            dateTaken = df.parse(date);
            }

    String file = scan.nextLine();
    file = file.trim();
    File photoFile = new File(file);

    //creates a Photo object from the information entered
    Photo Photo = new Photo(subject, location, dateTaken, photoFile);

    return Photo;
}

public static void main(String[] args) throws ParseException
{
    boolean endprogram = false;
    Scanner scan = new Scanner(System.in);

    //creates  a loop so that the user may enter as many photos as they wish
    while (!endprogram)
    {
        System.out.println("Would you like to enter a photo (y/n)?");

        //if the input is anything other than y, the program ends
        if(!scan.next().equalsIgnoreCase("y"))
        {
            endprogram = true;
        }
        else 
        {
            System.out.println(readPhoto(scan));
        }

    }
}

Answer 1

Everything runs fine when I am entering the information manually but when I try to use java PhotoTest < test.dat to get the input for[sic?] a file [...]

Does test.dat contain the "y" confirmations too? When you pipe in a file for stdin , the content of that file must be in legal format as if it was typed in manually.

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Also, you are creating another Scanner instance for stdin even though one is already passed to readPhoto . Are you sure you need to do this?

Answer 2

In your file you need a carriage return in the last line. That would be the equivalent to what you are typing manually. Note that when you are typing, in the last line you press enter.