Line numbers and text files Java

Question

I'm studying for my finals and i wondering if there is a particular way of printing out the data of a line in a text file. for example if i had the following in a text file:

11 
1c20 
203 
G2 

I was wondering if there is a way where I input for example 2 ,4 i would get an output 1c20 203 G2. by using two integers start and finish. i have research for this method, but unable to find anything. I understand there is a is a getLineNumber() but i want to use the two Integers.

Thanks in advance!

Answer 1

Here's an option (with pointers):

1. Read the inputs and store them in a two variables start and end
2. Read each line using BufferedReader#readLine, increase the counter for each line
3. If the line number is in the range, print the line.
4. When counter reaches end, break from the loop.

Answer 2

You might want to take a look at java.io.LineNumberReader: http://docs.oracle.com/javase/6/docs/api/java/io/LineNumberReader.html

Note that line numbers start at 0

Try this:

import java.io.*;

/*
 * Usage: java LinePrinter <start> <end>
 * Example: java LinePrinter 2 4
 */
public class LinePrinter
{
    public static void main(String[] args)
    {
        int start = Integer.parseInt(args[0]);
        int end = Integer.parseInt(args[1]);

        LineNumberReader reader = null;
        String line = null;
        boolean flag = false;

        try
        {
            reader = new LineNumberReader(new FileReader("data.txt"));

            while ((line = reader.readLine()) != null)
            {
                if (reader.getLineNumber() == start)
                {
                    flag = true;
                }

                if (flag)
                {
                    System.out.println(line);
                }

                if (reader.getLineNumber() == end)
                {
                    flag = false;
                    break;
                }
            }
        }
        catch (Exception e) {
            e.printStackTrace();
        }
    }
}