LineNumberReader Demo

import java.io.Reader;
import java.io.FileReader;
import java.io.LineNumberReader;
public class LineNumberDemo
{
    public static void main(String args[])
    {
        if(args.length < 1)
        {
            System.err.println("Usage: " + "java LineNumberDemo filename");
            System.exit(1);
        }
        new LineNumberDemo(args[0]);
    }
    /** Display a file with decimal line numbers.
     *  @param filename the file to be displayed
     */
    public LineNumberDemo(String filename)
    {
        try
        {
            FileReader       frdr = new FileReader(filename);
            LineNumberReader lrdr = new LineNumberReader(frdr);

            String line = lrdr.readLine();
            while ( line != null )
            {
                System.out.print(lrdr.getLineNumber() + ":\t");
                System.out.println(line.replaceAll("\t","    "));
                line = lrdr.readLine();
            }
        }
        catch(java.io.FileNotFoundException fnfx)
        {
            fnfx.printStackTrace();
        }
        catch(java.io.IOException iox)
        {
            iox.printStackTrace();
        }
    }
}