how can i incorporate my reader file to my program

[blknmld69]

My program works reading from values that I have stored in an array for valid account numbers. I also have a file that reads the valid account numbers from a text file. I need to read from the text file and not the array.

reads from array

import java.util.Scanner; 

   public class ChargeAccount 
   { 
      static int[] validChargeAccountNumbers = 
      { 
         5658845, 4520125, 7895122, 8777541, 8451277, 1302850, 8080152, 
         4562555, 5552012, 5050552, 7825877, 1250255, 1005231, 6545231, 
         3852085, 7576651, 7881200, 4581002 
         }; 
   
      public static void main(String[] args) 
      { 
         Scanner in = new Scanner(System.in); 
      
      // Ask the user for an account number 
         System.out.print("Please enter an account number: "); 
      
      // Get the number from the user 
         int number = in.nextInt(); 
      
      // Check to see if the number is valid 
         if (ChargeAccount.isValid(number) == true) 
         { 
            System.out.println("That account number is valid."); 
         } 
         
         else 
         { 
            System.out.println("You did not enter a valid account number."); 
         } 
      } 
   
   	// Check to see if an account number is valid by comparing it to the entries in the array of valid numbers 
      public static boolean isValid(int number)       
      { 
      
      // Perform sequential search through list of valid account numbers 
         for (int i = 0; i < validChargeAccountNumbers.length; i++) 
         { 
         
      // Check to see if the number we were given is at the ith position in the list 
         if (validChargeAccountNumbers[i] == number) 
         { 
            return true; 
         } 
      } 
      
      // If we get down here, then we never found it in the list 
         	return false; 
      } 
   }

file reader

mport java.io.*;

	
   class FileReadTest 
   {
      public static void main (String[] args) 
      {
         FileReadTest f = new FileReadTest();
         f.readMyFile();
      }
   
      void readMyFile() 
      {
         DataInputStream dis = null;
         String record = null;
         int recCount = 0;
      
         try 
         {
            File f = new File("valid_accounts.txt");
            FileInputStream fis = new FileInputStream(f);
            BufferedInputStream bis = new BufferedInputStream(fis);
            dis = new DataInputStream(bis);
         
            while ( (record=dis.readLine()) != null ) 
            {
               recCount++;
               System.out.println(recCount + ": " + record);
            }
         } 
			
			// catch io errors from FileInputStream or readLine()
            catch (IOException e) 
            {
               System.out.println("Uh oh, got an IOException error!" + e.getMessage());
            } 
         
         finally 
         {
         
          // if the file opened okay, make sure we close it
            if (dis != null) 
            {
               try 
               {
                  dis.close();
               } 
                  catch (IOException ioe) 
                  {
                  }
            }
         }
      }
   }

[Oralloy]

Try building a method similar to ReadMyFile(), which returns a collection of valid accounts. The type of collection would, of course, depend on how you are planning to use the account numbers.

import java.util.Set;
import java.util.HashSet;

public Set<Integer> ReadMyFile
{
  HashSet<Integer> result = new HashSet<Integer>;

  ...

  while( !eof )
  {
    ...
    result.add(new Integer(validAccount));
  }

  return result;
}

Hopefully this helps a little.

[blknmld69]

I just want it to basically check from the validAccounts.t xt file to see if the users input is a valid account.

[Oralloy]

Do you want to reload the file every time for the check, or just read the thing once?

Right now all you have are miscellaneous code bits that sort of solve your problem.

I take it that your assignment is to write a one-shot test to see if the account number is valid?

If you don't like the approach of returning a collection, then think procedurally.

You might use your current file read routine to test while reading - if no match is found by end-of file, then there is no match. (BTW, I notice that you are reading lines, not integer values. Were you planning on doing a comparison of strings or integers?)

You might hoist the file-read code to your isValid() method. Or even into the main routine.

If you need help converting text strings into integers, look up the documentation on Integer.decode( String).

Luck!

[blknmld69]

I have a two part assignment.

import java.util.Scanner; 

   public class ChargeAccount 
   { 
      static int[] validChargeAccountNumbers = 
      { 
         5658845, 4520125, 7895122, 8777541, 8451277, 1302850, 8080152, 
         4562555, 5552012, 5050552, 7825877, 1250255, 1005231, 6545231, 
         3852085, 7576651, 7881200, 4581002 
         }; 
   
      public static void main(String[] args) 
      { 
         Scanner in = new Scanner(System.in); 
      
      // Ask the user for an account number 
         System.out.print("Please enter an account number: "); 
      
      // Get the number from the user 
         int number = in.nextInt(); 
      
      // Check to see if the number is valid 
         if (ChargeAccount.isValid(number) == true) 
         { 
            System.out.println("That account number is valid."); 
         } 
         
         else 
         { 
            System.out.println("You did not enter a valid account number."); 
         } 
      } 
   
   // Check to see if an account number is valid by comparing it to the entries in the array of valid numbers 
      public static boolean isValid(int number) 
      { 
      // Perform sequential search through list of valid account numbers 
         for (int i = 0; i < validChargeAccountNumbers.length; i++) 
         { 
         // Check to see if the number we were given is at the ith position in the list 
            if (validChargeAccountNumbers[i] == number) 
            { 
               return true; 
            } 
         } 
      
      // If we get down here, then we never found it in the list 
         return false; 
      } 
   }

this works great. Now the second part is to read the valid accounts stored in the array above from a text file(valid_acco unts.txt)

[Oralloy]

Well, you've made a good start at your reader code. Don't throw that away.

You already know that you need to replace the static instantiation of the account number array.

First, have you got a strategy? Will you look at the file until found, or will you read the entire file and then see if the value is there? This determines how you will write your program.

Second, have you looked at using any of the java.util collection classes to manage the account numbers? Or hasn't your instructor introduced you to template classes, yet?

Third, if you are lost, try pseudo-coding your answer - solve the problem with words first. Then you can write Java code to implement your solution.

Lastly, has your instructor given you any out-of-band information, like maximum file size, or some such? This is important, because the kinds of considerations in production software are a little tougher than are usually applied to students' assignments.

Cheers!

[blknmld69]

Ok i have it reading from the text file now but it is only outputing "the account you entered is invalid even when I input the correct account number.

import java.io.BufferedReader; 
   import java.io.FileReader; 
   import java.io.IOException; 
   import java.util.Scanner; 
   import java.util.Vector; 

   public class ChargeAccount 
   { 
      static Vector<Integer> validChargeAccountNumbers = new Vector<Integer>(); 
   
   
      public static void main(String[] args) 
      { 
      //load the file
         readMyFile("valid_accounts.txt"); 
      
         Scanner in = new Scanner(System.in); 
      
      // Ask the user for an account number 
         System.out.print("Please enter an account number: "); 
      
      // Get the number from the user 
         int number = in.nextInt(); 
      
      // Check to see if the number is valid 
         if (isValid(number) == true) 
         { 
            System.out.println("That account number is valid."); 
         } 
         
         else 
         { 
            System.out.println("You did not enter a valid account number."); 
         } 
      } 
   
   // Check to see if an account number is valid by comparing it to the 
	// entries in the vector validChargeAccountNumbers 
      public static boolean isValid(int number) 
      { 
         return validChargeAccountNumbers.contains(number); 
      } 
   
      public static void readMyFile(String nameFile) 
      { 
         String record = null; 
         BufferedReader reader = null; 
         FileReader fr = null; 
         int recCount = 0; 
			
      // Code to read the file and store each account into the vector 
		// validChargeAccountNumbers 
      
      } 
   }

[Oralloy]

Excellent.

So now all you have to do is read from the file into your Vector, right?

The code is essentially the same as that you had earlier.

You're using a Scanner to read from the System.in stream, right?

What's wrong with using a Scanner to read from your account numbers file?

The only trick is detecting EOF, right? Scanner.nextInt () throws a java.util.NoSuc hElementExcepti on exception on end-of-input. The page is here.

So the control code will look something like:

try
{
  while(true)
  {
    value = myScanner.nextInt();
    validChargeAccountNumbers.add(value);
  }
}
catch (NoSuchElementException exception)
{
  // EOF is legitimate; all others will pass up the stack
}

Do you think you can do the rest?

[blknmld69]

actually no, I am late with this project. I have been working on it and have fallen behind in my other classes.

[blknmld69]

you mean something like this:

   import java.io.*;
   import java.util.Vector;

   public class readMyFile 
   {
      public static void main(String[] args) 
      {
         DataInputStream dis = null;
         String record = null;
         int recCount = 0;
         Vector<String> vAccounts = new Vector<String>();
      
         try 
         {
            File f = new File("valid_accounts.txt");
            FileInputStream fis = new FileInputStream(f);
            BufferedInputStream bis = new BufferedInputStream(fis);
            dis = new DataInputStream(bis);
         
            while ( (record=dis.readLine()) != null ) 
            {
               vAccounts.add(record);
               recCount++;
               System.out.println(recCount + ": " + record);
            }
         } 
         
         // catch io errors from FileInputStream or readLine()
            catch (IOException e) 
            {
               System.out.println("IOException error!" + e.getMessage());
            } 
         
         finally 
         {
         
         // if the file opened okay, make sure we close it
            if (dis != null) 
            {
               try 
               {
                  dis.close();
               } 
                  catch (IOException ioe) 
                  {
               }
            }
         }
      }
   }

[Oralloy]

Ouch. Then you are one frustrated kid.

Still, your code looks good. All you need is the read-file bit and you're done.

Did you ever bother to read that link I sent?

This is a simplified bit of code that might work for you, but it'll never fly in a production environment where people seem to put all kinds of junk in files. The problem is, of course, in error detection and reporting:

try {
  Scanner s = new Scanner(new File(fileName));
    	
  while(s.hasNextInt())
    validChargeAccountNumbers.add(s.nextInt());
} catch (FileNotFoundException e) {
  e.printStackTrace();
}

[blknmld69]

lol very confused old man (44). I will try that.

[Oralloy]

Eeeep, that makes me ancient (48).

[blknmld69]

where would that go?

[Oralloy]

Do you understand what the code example does?