Java: Reading File & Loop help

[khaos34]

Hi... I'm a newbie at Java, so I was wondering if you guys could help me out...

I have txt file i'm reading scores and labels off of to make a bar graph.

First line is an integer (score), second line is the label ("Score 1"), and they alternate from then on. I have 5 scores, meaning ten lines in the txt file.

Anyway, I can read the txt file and make the bar graph perfectly, but when i make the loop, i always have to specify how many times to do the loop... I have no idea how to make it count how many items are in the txt file automatically or to stop when there are no more values.

Please help if you can :o

Here is my code for the loop area so far:

 int n = 0;
  int itemCount = 5;

  SimpleReader reader = new SimpleReader( "graphdata.dat" );

  while ( n < itemCount )
 	 {
 	 double number = reader.getInt();
 	 r = new SimpleRectangle( BAR_START, barPos, (int) number, BAR_HEIGHT );
 	 r.setColor( barColor );
 	 r.setToFill();
 	 graphWin.add( r );
 	 total = total + number;
 	 n = n + 1;
 	 barPos = barPos + BAR_HEIGHT + BAR_SPACER;

 	 String word = reader.getString();
 	 lab = new SimpleLabel( LABEL_START, labelPos, LABEL_WIDTH, LABEL_HEIGHT );
 	 lab.setText( word + ": " + (int) number );
 	 graphWin.add( lab );
 	 labelPos = labelPos + LABEL_HEIGHT + LABEL_SPACER;
 	 }
  reader.safeClose();

[kjordan2001]

Well, I've got no idea what SimpleReader is, but if it's extending BufferedReader, reader.ready() will say if the file is ready or not.

So:

while(reader.ready()) {
........

or

while(reader.getInt() != *numberhere*)

If it returns an error number, just put that in the *numberhere*

It's hard though not knowing what your reader does or what methods it has to read the file with.

Edited February 4, 2003 by kjordan2001

[pagal]

you could use parseInt() easily with BufferedReader.

[obiwong]

i haven't touched java in a while but don't u have to put something like

while line != NULL

or something like that?

[ss1]

Use BufferedReader instead and to for the this question:

"or to stop when there are no more values"

use a while loop if the following code:

while (in.readLine() != null)
{
    //Code execution here
}

This code below is what i did some while back and should give you some hints on how to implement BufferedReader:

/**
 * Read Class - A Class that Read's a Text file
 * @author Saad Mahamood 
 * @version 10/10/02 
 */

import java.io.*;

public class Read  
{

    public Read()
    {
        //Default Constructor
    }


    /**
     * textFile - This method read's a text file and output's
     *            it's content's to the terminal
     *@execption - IOException 
     */
    public void textFile() throws IOException
    {
        File aFile = new File("read.txt");

        if ((!aFile.isFile()) || (!aFile.canRead()))
        {
            // Let's leave
            throw new IOException("File not found");
        }

            
        BufferedReader in = new BufferedReader(new FileReader(aFile));
        
        
        String theString = null;

        for (int i=0;i < 26; i++ ) 
        {
            theString = in.readLine();
            System.out.println(theString);
       	 
        }


    }



	public static void main(String[] args) 
	{
  System.out.println("Reading file");
        System.out.println("***********************");
        Read aread = new Read();
        try
        {
            aread.textFile();
        }
        catch(IOException e)
        {
            System.err.println("Anption occured!");
        }

	}
}

ss1.

[PeterHammer]

try {
    BufferedReader oBuffer = new BufferedReader(new FileReader(new File("Path\to\file.txt")));
} catch (FileNotFoundException e) {
    system.out.print("FileFound");
}

String s = null;
while(true) {
    s = oBuffer.readLine();
    if (s == null) break;

    //Do your Rectangle business here
}

BTW: IF you are finding you have to create your own readers and writers and you are a newbie, then you are going down the wrong path. The book "Core Java2" from Sun Press has a good chapter that deals with the intricacies of Readers and Writers (and InputStreams and OutputStreams). I suggest you read it. It will spare you a lot of time later down the line.

Also, try not to initialize your objects inside of a loop. You have a line

String word = reader.getString();

inside your loop. That is not very efficient. While not technically wrong, it is a bad habit to get into.

FREE TIP: (and off-topic) On a related note, careful with string concatenation inside loops. You don't do it on the example you supplied, but if you are reading a file the last thing you want to do is:

String s = new String();
String temp = null;
while (true) {
    temp = oBuffer.readLine();
    if (temp == null) break;
    s += temp;
}

If you read the book above, or any text on the net, you will learn to use a StringBuffer for this kind of operation.

Edited February 11, 2003 by PeterHammer

[khaos34]

sorry for the lack of reply the past few days, i haven't had a chance to jump back on the computer...

thanks for all your help... I'm a total newbie to Java, and i just found out how stupid it was to post the code that I have, since I found out that SimpleReader and all that stuff were custom classes from my teacher. sorry about that.

thanks for all your help though, i got it working now =)

thanks for all your help with BifferedReader also, I think i'm gonna study up on that one more... I'll read up a bit more before I ask for the next question.

Thanks again, and I really appreciate all of your help guys. :D