RandomAccessFile help

[john-paul York]

I am working on a program and am 95% done, but am stuck. My program creates a file and the user can file it with account ID's and balances. The issue I am having is that when a user enters a duplicate account ID it needs to throw an error and I am thinking after the error it should then ask for more ID's. At this point I can enter all the ID's I want and after I enter a duplicate entry it does throw the error, but then the program exits. How do I get it to continue asking for ID's.....any hints?

import javax.swing.*;
import java.io.*;
public class CreateBankFile 
{
	public static void main (String[] args) throws IOException, DuplicateAccountException
	{
		int pos;
		RandomAccessFile bankFile = new RandomAccessFile("BankFile.dat", "rw");
		int accountID=0;
		double balance=0.0;
		int duplicate=0;
		final int MAXSIZE = 12;
		final int MAXRECORDS = 9999;
		final int END = 99999;
		
		try
		{
		
		for (int counter = 0; counter <MAXRECORDS; ++counter) //creates my blank entries I need
			{
			bankFile.writeInt(0);
			bankFile.writeDouble(0.0);
			}
		}
		
		catch(IOException exception)
		{
			System.out.println("Error: " + exception.getMessage());
		}
		
		finally
		{
			bankFile.close();
		}
		
		bankFile = new RandomAccessFile("BankFile.dat", "rw");
		try
		{
			
		    accountID = Integer.parseInt(JOptionPane.showInputDialog(
                         null, "Enter customers account ID or " + END + " to quit program.")); //intake account ID
		    
		    while(accountID != END)  
		    {
		    	
		    	for(int x = 0; x < MAXRECORDS; ++x)  //search the file for a duplicate entry
		    	{
		    	bankFile.seek(x*MAXSIZE);
		    	duplicate=bankFile.readInt();
		    	if(duplicate==accountID)
		    		{
		    		throw(new DuplicateAccountException());  //throw error is duplicate found
		    		}
		    	else
		    	{
		    		continue;  //no duplicates continue on to next if statement
		    	}
		    	
		    	}
		    
		    	
		    	
		    	if((accountID>=0) &&(accountID<=MAXRECORDS)) 
/*
 * below I do not have issues if it makes it this fare below works, the 
 * issue I have is after finding one duplicate it just ends the program and bypasses trying to enter more ID's
 */
                       {
		    		balance = Double.parseDouble(JOptionPane.showInputDialog(
                                      null, "Enter customers balance"));
		    		pos=accountID;
		    	    bankFile.seek(pos*MAXSIZE);
		    	    bankFile.writeInt(accountID);
		    	    bankFile.writeDouble(balance);
		    		accountID = Integer.parseInt(JOptionPane.showInputDialog(
                                     null, "Enter customers account ID or " + END + " to quit program."));
	    
		    	}
		    	else
		    	{
		    			JOptionPane.showMessageDialog(
                                                  null, "Account ID not valid, must be between 1 and 10000.");
		    			accountID = Integer.parseInt(
                                                 JOptionPane.showInputDialog(null, "Enter customers account ID or " + END + " to quit program."));
		    	}

		    }
		}
		
		catch(DuplicateAccountException dae)
		{
			JOptionPane.showMessageDialog(null,"Account ID already entered");
		}
		catch(IOException exception)
		{
			System.out.println("Error: " + exception.getMessage());
		}
		
		finally
		{
			bankFile.close();
			JOptionPane.showMessageDialog(null, "Exiting Program");
		}
	}
	
	
}

[edit]Break long lines and change // comments to /* */ to reduce horizontal scrolling CR[/edit]

[Campbell Ritchie]

It is probably a bad idea to throw and catch the same Exception in one method. When you throw your Exception, you are transferring control outwith the loop. So the program will terminate.

[Stephan van Hulst]

It's pretty simple, move the DuplicateAccountException catch block inside the while loop.

What I would be more concerned about is that you're keeping the file open all the time, and doing your checking directly from the file.
It's probably a better idea to read all the IDs into a set first, and then checking the set whether it already contains the ID. This will be much more efficient than seeking the disk.

Also, consider splitting up your program into separate methods. This will make it easier to read and maintain the program.

[john-paul York]

Thanks for the tips...when I load up my work laptop later tonight I will definitly play with the file and try your suggestions...much appreciated.