Thread: Trying to out.println of random selected record

Hello this program is supposed to read the data of a specified .txt file which it does then it promts you to pick a specfic line of data from that .txt file it compiles fine but will not write data on screen of selected data

 
import java.nio.file.*;
import java.io.*;
import java.nio.file.attribute.*;
import static java.nio.file.StandardOpenOption.*;
import java.nio.ByteBuffer;
import java.nio.channels.FileChannel;
import java.util.Scanner;
public class ReadStateFile
{
	public static void main(String[] args)
	{
		Scanner kb = new Scanner(System.in);
		String fileName;
		System.out.print("Enter name of file to use >> ");
		fileName = kb.nextLine();
		fileName = fileName;
		Path file = Paths.get(fileName);
		final String ID_FORMAT = "000";
		final String NAME_FORMAT = "          ";
		final int NAME_LENGTH = NAME_FORMAT.length();
		final String HOME_STATE = "WI";
		final String BALANCE_FORMAT = "0000.00";
		String delimiter = ",";
		String s = ID_FORMAT + delimiter + NAME_FORMAT + delimiter + HOME_STATE + delimiter + BALANCE_FORMAT + System.getProperty("line.separator");
		final int RECSIZE = s.length();
		byte data[] = s.getBytes();
		final String EMPTY_ACCT = "000";
		String[] array = new String[4];
		double balance;
		double total = 0;
	try
	{
		BasicFileAttributes attr = Files.readAttributes(file, BasicFileAttributes.class);
		System.out.println("\nAttributes of the file:");
		System.out.println("Creation time " + attr.creationTime());
		System.out.println("Size " + attr.size());
	}
	catch(IOException e)
	{
		System.out.println("IO Exception");
	}
	try
	{
		InputStream iStream = Files.newInputStream(file, READ);
		BufferedReader reader = new BufferedReader(new InputStreamReader(iStream));
		System.out.println("\nAll non-default records:\n");
		s = reader.readLine();
		while(s != null)
		{
			array = s.split(delimiter);
			if(!array[0].equals(EMPTY_ACCT))
			{
				balance = Double.parseDouble(array[3]);
				System.out.println("ID #" + array[0] + " " + array[1] + array [2] + " $" + array[3]);
				total += balance;
			}
			s = reader.readLine();
		}
		System.out.println("Total of all balances is $" + total);
		reader.close();
	}
	catch(Exception e)
	{
		System.out.println("Message: " + e);
	}
	try
	{
		FileChannel fc = (FileChannel)Files.newByteChannel(file, READ, WRITE);
		ByteBuffer buffer = ByteBuffer.wrap(data);
		int findAcct;
		System.out.print("\nEnter acount to seek >> ");
		findAcct = kb.nextInt();
		fc.position(findAcct * RECSIZE);
		fc.read(buffer);
		s = new String(data);
		System.out.println("Desired record: " + s);
	}
	catch(Exception e)
	{
		System.out.println("Message: " + e);
	}
	}
}

first request looks like this in jGRASP


Enter name of file to use >> InStateCusts.txt

Attributes of the file:
Creation time 2012-11-10T18:57:35.21Z
Size 32000

All non-default records:

ID #101 Franklin WI $1034.38
ID #104 Samuels WI $0100.99
Total of all balances is $1135.37


Enter acount to seek >> 101

\\ heres where it goes wrong its supposed to repeat the requested data and i get

Desired record: ,WI,0000.00
00

any help would be appericated!

Im taking a class called intro to computer programming

to compile it our teacher has us using jGRASP latest version and the book we are using is Java Programming Sixth Edition by Joyce Farrell

 
import java.nio.file.*;
import java.io.*;
import java.nio.channels.FileChannel;
import java.nio.ByteBuffer;
import static java.nio.file.StandardOpenOption.*;
import java.util.Scanner;
import java.text.*;
public class CreateFilesBasedOnState
{
	public static void main(String[] args)
	{
		Scanner input = new Scanner(System.in);
		Path inStateFile = 
			Paths.get("InStateCusts.txt");
		Path outOfStateFile = 
			Paths.get("OutOfStateCusts.txt");
		final String ID_FORMAT = "000";
		final String NAME_FORMAT = "               ";
		final int NAME_LENGTH = NAME_FORMAT.length();
		final String HOME_STATE = "WI";
		final String BALANCE_FORMAT = "0000.00";
		String delimiter = ",";
		String s = ID_FORMAT + delimiter + NAME_FORMAT + delimiter + HOME_STATE + delimiter + BALANCE_FORMAT + System.getProperty("line.separator");
		final int RECSIZE = s.length();
		FileChannel fcIn = null;
		FileChannel fcOut = null;
		String idString;
		int id;
		String name;
		String state;
		double balance;
		final String QUIT = "999";
 
		createEmptyFile(inStateFile,s);
		createEmptyFile(outOfStateFile,s);
 
		try
		{
			fcIn = (FileChannel)Files.newByteChannel(inStateFile,CREATE, READ, WRITE);
			fcOut = (FileChannel)Files.newByteChannel(outOfStateFile,CREATE, READ, WRITE);
			System.out.print("Enter customer account number >>");
			idString = input.nextLine();
			while(!(idString.equals(QUIT)))
			{
				id = Integer.parseInt(idString);
				System.out.print("Enter name for customer >>");
				name = input.nextLine();
				StringBuilder sb = new StringBuilder(name);
				sb.setLength(NAME_LENGTH);
				name = sb.toString();
				System.out.print("Enter state >>");
				state = input.nextLine();
				System.out.print("Enter balance >>");
				balance = input.nextDouble();
				input.nextLine();
				DecimalFormat df = new DecimalFormat(BALANCE_FORMAT);
				s = idString + delimiter + name + delimiter + state + delimiter + 
					df.format(balance) + System.getProperty("line.separator");
				byte data[] = s.getBytes();
				ByteBuffer buffer = ByteBuffer.wrap(data);
				if(state.equals(HOME_STATE))
				{
					fcIn.position(id*RECSIZE);
					fcIn.write(buffer);
				}
				else
				{
					fcOut.position(id*RECSIZE);
					fcOut.write(buffer);
				}
				System.out.print("Eneter next customer account number or " + QUIT + " to quit >>");
				idString = input.nextLine();
			}
				fcIn.close();
				fcOut.close();
			}
		catch(Exception e)
		{
			System.out.println("Error message:" + e);
		}
	}
	public static void createEmptyFile(Path file,String s)
	{
		final int NUMRECS = 1000;
		try
		{
			OutputStream outputStr = Files.newOutputStream(file, CREATE);
			BufferedWriter writer = new BufferedWriter(new OutputStreamWriter(outputStr));
			for(int count = 0; count < NUMRECS; ++count)
				writer.write(s, 0, s.length());
			writer.close();
		}
		catch(Exception e)
		{
			System.out.println("Error message:" + e);
		}
 
	}
}

this is the input program i have the file location set to default which is same location as where the program is saved, this was a You Do It assignment right out of the book but we found that the book has some syntex errors as far as: OutputSteam commands in the book it was

OutputStream outputStr = new BufferedOutputStream(file.newOutputStream(CREATE)) ;

and the proper updated syntex is

OutputStream outputStr = Files.newOutputStream(file, CREATE);

so im wondering if there might be a problem in the FileChannel Position if statement

fcIn.position(findAcct * RECSIZE);

but i cant see the problem but as far as i can tell when you go to select the specific file by typeing in the ID # its not properly locating it.


thanks again for repling

Yes sir as of right now it compiles and runs fine using jGRASP the problem is its not recalling the selected file properly as far as your errors go maybe you compiler is using the same syntax from the book when I get home from work ill post the code that is right out of the book. The ones that I had to change because jGRASP did not like the syntax

After we downloaded jGRASP the teacher also instructed us to download JDK 7 and JRE from oracles website of that helps

Ya I reinstalled them the day I posted the question I'm not sure the problem I know that another student uses notepad ++ to write the code and then uses the command line to compile and run the program and he had an issue where it wasn't compiling durning command line but when he opened jGRASP it compiled fine maybe this is the same thing?

First run the the class CreateFileBasedOnState input a few data the after your done exit program with 999 then it should create the two files in the folder you designated then run the sec program ReadStateFile your prompted to enter file name if your using same names you enter either InStateCusts.txt or OutOfStateCusts.txt make sure you add the .txt it wouldn't work if I didn't then the program should bring up the data you entered the prompt you to choose a file by entering the ID # and its supposed to repeat that file back to you but mine doesn't

I kinda understand but we were not required to use a scanner the program was designed for user input so ID numbers are rand three digits a name up to ten characters long two digit state abrv. And then balance which is 0000.00 we defined in program but I guess if I'm doing scanner right it would be something like this

 
Scanner input = new Scanner("213\nWalters\nAZ\n1234.88\n");
Scanner input = new Scanner("104\nSamuels\nWI\n44.44\n");
Scanner input = new Scanner("106\nDavis\nWI\n234.54\n");
Scanner input = new Scanner("215\nJohnsonville\nFL\n1034.69\n999\n");

If I'm understanding this right you should have four sets of data two will be placed into the out of state file and two into the in state file as WI is defined in program as in state Walters and Johnsonville should be placed in the out of state but as I said before the data is user defined there was no set norm.

The lines that you are getting in the file are correct and they are in order so if you used ID# 102 you would have to scroll down to the 102nd line of that data.

As far as the scanner data it is outside of my scope of understanding to be able to provide you with the appropriate line of coding.

Ok I'll give it a try when I get home where you able to get the data to display when the sec program prompted you to enter the account you seek