A utility to remove line numbers from a file which contains the number of the line at the beginning of that line for each line.

LineNumberRemover.java

import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.File;
import java.io.FileReader;
import java.io.FileWriter;
import java.io.IOException;
import java.util.ArrayList;
import java.util.List;

public class LineNumberRemover {

	public static void main(String... arguments) throws IOException {

		if (arguments.length < 1) {
			System.out.println("Please supply the path of the file to" +
					" remove line numbers from in the command-line arguments.");
			return;
		}

		List<String> new_lines = readAndRemove(arguments[0]);
		writeNewFile(new_lines, arguments[0]);

	}

	private static List<String> readAndRemove(String file_path) throws IOException {
		BufferedReader reader = new BufferedReader(new FileReader(file_path));
		List<String> new_lines = new ArrayList<String>();
		try {
			for (int i = 1; i < Integer.MAX_VALUE; i++) {
				String line = reader.readLine();
				if (line != null) {
					if (line.contains(String.valueOf(i))) {
						String new_line = line.substring(line.indexOf(String.valueOf(i)) + String.valueOf(i).length());
						new_lines.add(new_line);
					}
				} else {
					break;
				}
			}
		} finally {
			reader.close();
		}
		return new_lines;
	}

	private static void writeNewFile(List<String> new_lines, String old_file_path) throws IOException {
		File new_file = new File(old_file_path + ".new");
		new_file.createNewFile();

		BufferedWriter writer = new BufferedWriter(new FileWriter(new_file));

		try {
			for (String line : new_lines) {
				writer.write(line + "\n");
			}
		} finally { 
			writer.close();
		}
	}

}