Is it a bug in Sun's Tutorial example!!!!

Question

Hello everybody! I donno whether the following Tutorial example code is buggy or not but it won't run under j2sdk 1.4.2 and also under 1.5 as smoothly as Tutorial says(only the 1st line prints but not all). You can find the code:
http://java.sun.com/docs/books/tutorial/essential/io/dataIO.html
And the file name is:
DataIODemo
Does anyone know how to make it work?
Thanks.
--DM                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               

Answer 1

The author made a "bonehead" error - s/he hardcoded a newline character ('\n') when writing the invoice1.txt file. Since this is a UNIX/Linux character, it will not cause an error when run there - BUT - when run on an OS that doesn't use that convention - Windows, etc - it results in an incorrectly written file.
This illustrates a code portability problem; don't hardcode!
I leave as an exercise for the reader the correction of the format of the total dollar amount.
A corrected copy is below. //********* preceeds changes. Compare with the original to see the differences.
import java.io.*;
public class DataIODemo
    public static void main(String[] args)
        throws IOException
        // write the data out
        DataOutputStream out  = new DataOutputStream(new
            FileOutputStream("invoice1.txt"));
        double[] prices       = {19.99, 9.99, 15.99, 3.99, 4.99};
        int[] units           = {12, 8, 13, 29, 50};
        String[] descs        = {"Java T-shirt",
            "Java Mug",
            "Duke Juggling Dolls",
            "Java Pin",
            "Java Key Chain"};
        char lineSep          = System.getProperty("line.separator").charAt(0);
        for (int i = 0; i < prices.length; i++)
            out.writeDouble(prices);
out.writeChar('\t');
out.writeInt(units[i]);
out.writeChar('\t');
out.writeChars(descs[i]);
out.writeChar(lineSep);
out.close();
// read it in again
DataInputStream in = new DataInputStream(new
FileInputStream("invoice1.txt"));
double price;
int unit;
StringBuffer desc;
double total = 0.0;
try
while (true)
price = in.readDouble();
in.readChar();
// throws out the tab
unit = in.readInt();
in.readChar();
// throws out the tab
char chr;
desc = new StringBuffer(20);
while ((chr = in.readChar()) != lineSep)
desc.append(chr);
System.out.println("You've ordered " +
unit + " units of " +
desc + " at $" + price);
total = total + unit * price;
} catch (EOFException e)
System.out.println("For a TOTAL of: $" + total);
in.close();