Need Help With Assignment

[ans025]

Hello I am very new to Java and I really don't know exactly what I am doing. I know a little bit of other programming languages so I'm trying my best to figure it out for myself but I am supposed to:
Write a Java Application which will read a text file of scores from college football games and calculate the average home field advantage for that data.

import java.io.*;
import java.util.Scanner;
import java.util.logging.Level;
import java.util.logging.Logger;

public class HomeField
{
	public static void main(String [] args) 
	{
		String fileName;
		File inFile;
		Scanner kbd, input = null;
		String line;
                int LineCount = 0;
                int total = 0;

                //Create scanner object for keyboard input
		kbd = new Scanner(System.in);
                //Get the filename.
		System.out.print("Enter a filename: ");
		fileName = kbd.nextLine();
                //Open the file.
		inFile = new File(fileName);
        try {
            input = new Scanner(inFile);
        } catch (FileNotFoundException ex) {
            Logger.getLogger(HomeField.class.getName()).log(Level.SEVERE, null, ex);
        }
        

		while(input.hasNextLine())
		{
                // read a line from text
                line=input.nextLine();
                // increment line counter
                LineCount++;
                // pull off the visting team score from col 39-42  (use substring(), trim(), parseInt()
                String vscore = line.substring(38,4);
                vscore=vscore.trim();
                int vnum = Integer.parseInt(vscore);
                // pull off the home team score from col 71-74
                String hscore=line.substring(70,4);
                hscore=hscore.trim();
                int hnum=Integer.parseInt(hscore);

                //  add the difference (home - vistor) to
                total=hnum-vnum;
                total +=total;
		}
                // compute average
                double average=total/LineCount;

                // print out the average with an appropriate label
                System.out.println("The average is: " + average);
	}
}

The error that I'm getting is
java.lang.NoClassDefFoundError: HomeField/HomeField
Caused by: java.lang.ClassNotFoundException: HomeField.HomeField
at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
at java.security.AccessController.doPrivileged(Native Method)
at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
at java.lang.ClassLoader.loadClass(ClassLoader.java:307)
at sun.misc.Launcher$AppClassLoader.loadClass(Launcher.java:301)
at java.lang.ClassLoader.loadClass(ClassLoader.java:248)
Could not find the main class: HomeField.HomeField. Program will exit.
Exception in thread "main" Java Result: 1

Please help if you can.

[musthafa.aj]

when i was tried this program i found nothing wrong..

how do you give file name as input..

if u give just file name like "test.txt"..it thorws error..

but if u give exact path of the file like "c:\\temp\\test.txt"..it is fine..

check it once again..and post the exact error and how did you given input...

[NormR1]

How are you executing the program? Are you using the java command?
The error message says you entered: java HomeField.HomeField as the commandline.
Try java HomeField

[ans025]

I tried both using Netbeans IDE and just the command prompt. I got the error the first time using Netbeans.

When I used the command prompt I did:
javac HomeField.java
java HomeField

I've tried typing the file with paths and without but it still comes up with this error on command prompt and Netbeans:

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: -34
at java.lang.String.substring<Unknown Source>
at HomeField.main<HomeField.java:38

This last one changes from 38 to 33, to 41 on various runs

I changed the code a little bit

import java.io.*;
import java.util.Scanner;

public class HomeField
{
	public static void main(String [] args) throws FileNotFoundException
	{
		String fileName;
		File inFile;
		Scanner kbd, input = null;
		String line;
                int LineCount = 0;
                int total = 0;

                //Create scanner object for keyboard input
		kbd = new Scanner(System.in);
                //Get the filename.
		System.out.print("Enter a filename: ");
		fileName = kbd.nextLine();
                //Open the file.
		inFile = new File(fileName);
                input = new Scanner(inFile);



		while(input.hasNextLine())
		{
                // read a line from text
                line=input.nextLine();
                // increment line counter
                LineCount++;
                // pull off the visting team score from col 39-42  (use substring(), trim(), parseInt()
                String vscore = line.substring(38,4);
                vscore=vscore.trim();
                int vnum = Integer.parseInt(vscore);
                // pull off the home team score from col 71-74
                String hscore=line.substring(70,4);
                hscore=hscore.trim();
                int hnum=Integer.parseInt(hscore);

                //  add the difference (home - vistor) to
                total=hnum-vnum;
                total +=total;
		}
                // compute average
                double average=total/LineCount;

                // print out the average with an appropriate label
                System.out.println("The average is: " + average);
	}
}

[java_programmer]

Check the text file you providing as input.
The error shows that it does not contain anything in the index specified
in the subString() method...

[NormR1]

Are you still getting this error?

The error that I'm getting is
java.lang.NoClassDefFoundError: HomeField/HomeField

Can you run it again in the command prompt and copy the full contents of the command prompt window here?

[ans025]

I attached the text file I am using for the data.

This is exactly the error the command prompt gave

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: -34
at java.lang.String.substring<Unknown Source>
at HomeField.main<HomeField.java:33>

[NormR1]

This error message says there was an error on line 33 of your program.
The index had a value of -34.

Look at line 33 of your code and figure out how there could be an index of -34

This line assumes that the line has > 38 characters. You need to test that the line is long enough before trying to use the 38 index.
String vscore = line.substring(38,4);

[ans025]

Well the line goes all the way past 74. I know this is a basic question but when you say index I really don't understand how it could be -34 anyway. The exact file I'm using is included in my previous post

[ans025]

Ok nevermind I got it past that point by changing the line numbers on line 33 and 37.

[NormR1]

Ok, problem solved?