Thread: Two questions, 1st having to do with File I/O, second needing advice on how to process contents from an input file

You don't 'skip' the first value in the file. If you don't want to use it, collect it and then throw it away. However, the purpose of the number 10 is to give you a value to use in a loop to gather the rest of the values from the file.

You're misinterpreting your error message. It's not that the file cannot be found, it says:

error: unreported exception FileNotFoundException; must be caught or declared to be thrown

Which means there is a possible exception that must be handled. The existence of the exception is mentioned on the Scanner API page, and here's an example of how to handle it.

Thank you for the tip on the try catch construct, I thought because the file obviously existed I didn't need to put anything in for exceptions but I guess not. When I compile the program now though it's not printing the stack trace so I assume it found the file, but my scanner object isnt being recognized, which means that it didn't find the file?

Here's an updated version of my code.

import java.util.*;
import java.io.*;
 
public class QudratullahMommandi_3_07
{
 
 
  public static void main (String[]args)
  {
 
  String numberOfValues;
  double rentalCost;
  double mileage;
  int controlVar;
  String inputFile = "C:\\Users\\Qudratullah\\Documents\\CSprograms\\QudratullahMommandi_3_07_Output";
 
   SummaryStatement();
 
  try
   { File inputSource = new File(inputFile);
    Scanner inputRead = new Scanner(inputSource);
   }
  catch (FileNotFoundException e)
   { e.printStackTrace();
   }
 
   TableHeading();
 
   numberOfValues = inputRead.nextLine();
   controlVar = Integer.parseInt(numberOfValues);
 
   for (int index = 0; index < controlVar; index++);
    { mileage = inputRead.nextDouble();
 
      if (mileage <=0)
      { System.out.println("*****");
      }
      else if (mileage < 400)
      { rentalCost = mileage*.18;
      }
      else if (mileage < 900)
      { rentalCost = 65.00 + (.15 * (mileage-400));
      }
      else if (mileage < 1300)
      { rentalCost = 115.00 + (.12 * (mileage-800));
      }
      else if (mileage < 1900)
      { rentalCost = 140.00 + (.10 * (mileage-1200));
      }
      else if (mileage < 2600)
      { rentalCost = 165.00 + (.08 * (mileage-1800));
      }
      else if (mileage >= 2600)
      { rentalCost = 195.00 + (.06 * (mileage-2500));
      }
 
     }
 
 
 
  }// end main
 
 
 
 
  public static void SummaryStatement()
  { System.out.println("This program reads a list of values representing number of miles"
      + " driven by individuals.\n" + "It will output the dollar amount their rental cars cost.");   
  }// end SummaryStatement
 
 
  public static void TableHeading()
  { System.out.println();
      System.out.println("Number of miles traveled on the left as well as amount reimbursed on the right");
      System.out.println("------------------------------------------------");
      System.out.println("Miles Driven" + "                   " + "Amount reimbursed");
  }
 
 }// end class

This is the error I get now

QudratullahMommandi_3_07.java:29: error: cannot find symbol
numberOfValues = inputRead.nextLine();
^
symbol: variable inputRead
location: class QudratullahMommandi_3_07
QudratullahMommandi_3_07.java:33: error: cannot find symbol
{ mileage = inputRead.nextDouble();
^
symbol: variable inputRead
location: class QudratullahMommandi_3_07
2 errors

Originally Posted by Norm

The variable in the error message is defined inside of a pair of {}s and is out of scope where the code is trying to use it.
You can define a variable outside of the {}s and give it a value inside of the {}s so it is in scope where it is being used.

Also the formatting of the code needs to be fixed so that the { and } line up one above the other. There should NOT be code on the same line following a { because that tends to hide the { making the logic harder to understand.

I fixed up the code for readability, my prof has weird formatting guidelines. The problem still remains that the file isnt being found though. I've tried deleting it and creating a new one with no luck. All my java files are in mydocs which is the default folder they were in when I installed Jgrasp, and my text file is in there as well so I don't know why its not being able to find the file.

This is the error message
----jGRASP exec: java QudratullahMommandi_3_07

This program reads a list of values representing number of miles driven by individuals.
It will output the dollar amount their rental cars cost.
Exception in thread "main" java.io.FileNotFoundException: C:\Users\Qudratullah\Documents\CSprograms\Qudratul lahMommandi_3_07_Output.txt (The system cannot find the file specified)
at java.io.FileInputStream.open(Native Method)
at java.io.FileInputStream.<init>(FileInputStream.jav a:146)
at java.util.Scanner.<init>(Scanner.java:656)
at QudratullahMommandi_3_07.main(QudratullahMommandi_ 3_07.java:19)

----jGRASP wedge2: exit code for process is 1.
----jGRASP: operation complete.

import java.util.*;
import java.io.*;
 
public class QudratullahMommandi_3_07
{
 
 
  public static void main (String[]args)throws IOException
  {
 
  String numberOfValues;
  double rentalCost;
  double mileage;
  int controlVar;
  String inputFile = "C:\\Users\\Qudratullah\\Documents\\CSprograms\\QudratullahMommandi_3_07_Output.txt";
 
   SummaryStatement();
   File file = new File(inputFile);
   Scanner inputRead = new Scanner(file);
 
 
 
   TableHeading();
   numberOfValues = inputRead.nextLine();
   controlVar = Integer.parseInt(numberOfValues);
 
   for (int index = 0; index < controlVar; index++);
    { 
      mileage = inputRead.nextDouble();
 
      if (mileage <=0)
      { 
       System.out.println("*****");
      }
      else if (mileage < 400)
      { 
       rentalCost = mileage*.18;
      }
      else if (mileage < 900)
      { 
       rentalCost = 65.00 + (.15 * (mileage-400));
      }
      else if (mileage < 1300)
      { 
       rentalCost = 115.00 + (.12 * (mileage-800));
      }
      else if (mileage < 1900)
      {
        rentalCost = 140.00 + (.10 * (mileage-1200));
      }
      else if (mileage < 2600)
      {
        rentalCost = 165.00 + (.08 * (mileage-1800));
      }
      else if (mileage >= 2600)
      { 
       rentalCost = 195.00 + (.06 * (mileage-2500));
      }
 
     }// end for loop
 
 
 
  }// end main
 
 
 
 
  public static void SummaryStatement()
  { 
      System.out.println("This program reads a list of values representing number of miles"
      + " driven by individuals.\n" + "It will output the dollar amount their rental cars cost.");   
  }// end SummaryStatement
 
 
  public static void TableHeading()
  { 
      System.out.println();
      System.out.println("Number of miles traveled on the left as well as amount reimbursed on the right");
      System.out.println("------------------------------------------------");
      System.out.println("Miles Driven" + "                   " + "Amount reimbursed");
  }
 
 }// end class

Unfortunately, this is more of a jGrasp question than a Java question, and we would need to be using jGrasp to understand how to solve your problem. Since few here (none?) use jGrasp, we don't know what to advise. Others in your class or the instructor/TAs should be able to help. I couldn't find anything in the jGrasp documentation that helped, but it's difficult to be sure without using the tool.

Good luck.