How do I fix my program?

Code :

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/*This program will allow the user to search for a particular 
  file he/she desires and count the number of times a particular
  substring occurs in the file.
*/
 
import java.util.Scanner;
import java.io.*;
 
public class Assignment4
{
	public static void main(String[] args) throws IOException
	{
		int count = 0;
 
		Scanner keyboard = new Scanner(System.in);
 
		System.out.println("Enter the name of the file you would like" +
			" to search.");
		String fileName = keyboard.nextLine();
 
		File file = new File(fileName);
 
		if(!file.exists())
		{
			System.out.println("The file " + fileName + "is not found.");
			System.exit(0);
		}
 
		Scanner inputFile = new Scanner(file);
 
		System.out.print("Enter the substring you would like to find" + 
			" the occurance of:  ");
		String userSearch = keyboard.nextLine();
		int stringSize = userSearch.length();
		int stringStart = userSearch.charAt(stringSize);
 
		while(stringStart != -1 && stringSize != -1)
		{
			count++;
		}
 
 
		System.out.print(count + "occurences of the substring " + "\"" +
			userSearch + "\" were found in " + fileName + ".");
 
		inputFile.close();
	}
}

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so there is my code, the object of this program is to count the number of occurrences of a particular sub string in a file.
My teacher said it can be done with the charAt and length methods of a String.
My while loop is messed up, which is the main problem with my program.

And what is your question? Does it compile? Does it misbehave? Are there exceptions? Please see the link in my signature entitled getting help

So it appears that you've given us the code your teacher gave to you, and you need to fill in the while loop? You're right, that's where the problem is. At this point, your while loop really doesn't do anything useful at all, does it?
Do you have an idea of what is should accomplish?

You want to find some substrings, so you're going to be moving along the file. You want your while loop to exit when you run out of string to traverse, so you must be deleting stuff from the string after you look at it. You know how long your string is going to be (stringLength).

So, start moving through the string, evaluating things using charAt and comparing them with your string, then deleting stuff you've already looked at.

thanks for the replies.
it does compile however it does not do much if anything like you said.

Quote:

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So, start moving through the string, evaluating things using charAt and comparing them with your string, then deleting stuff you've already looked at.

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yeah that's pretty much the goal of this program. I just have to count the number of instances that the particular substring occurred. but I'm having trouble constructing the proper loop to do the job. I'm thinking a while loop would be adequate..

Attachment 845

So implement the while loop and come back to us if you have a specific problem with it...