Solved

getting # of lines in file

Posted on 2004-03-28
6
333 Views
Last Modified: 2010-03-31
hello, how can i get the number of lines in a text file without looping though the lines?
0
Comment
Question by:91mustang
[X]
Welcome to Experts Exchange

Add your voice to the tech community where 5M+ people just like you are talking about what matters.

  • Help others & share knowledge
  • Earn cash & points
  • Learn & ask questions
  • 3
  • 2
6 Comments
 
LVL 86

Expert Comment

by:CEHJ
ID: 10699253
You can't really. Why would you want to though?
0
 
LVL 4

Author Comment

by:91mustang
ID: 10699258
I have an app that reads a file in line parses line, inserts to DB,next line....

I want to use a Jprogress bar and use the number of lines in file as the maximum value for proggress bar
0
 
LVL 86

Accepted Solution

by:
CEHJ earned 20 total points
ID: 10699282
You could do something like this:


import java.util.regex.*;
import java.nio.*;
import java.nio.charset.*;
import java.nio.channels.*;
import java.io.*;

/**
 *  Description of the Class
 *
 * @author     CEHJ
 * @created    28 March 2004
 */
public class LineCount2 {

      public static void main(String[] args) throws Exception {
            if (args.length < 1) {
                  System.out.println("Usage: java LineCount2 <text file to count lines of>");
                  System.exit(-1);
            }
            int count = 0;
            FileChannel roChannel = new RandomAccessFile(new File(args[0]), "r").getChannel();
            ByteBuffer bbuf = roChannel.map(FileChannel.MapMode.READ_ONLY, 0, (int) roChannel.size());
            CharBuffer cbuf = Charset.forName(System.getProperty("file.encoding")).newDecoder().decode(bbuf);

            Pattern EOL = Pattern.compile("\\n");
            Matcher matcher = EOL.matcher(cbuf);
            while (matcher.find()) {
                  count++;
            }
            if (cbuf.length() > 0) {
                  ++count;
            }
            System.out.println(count + " lines found");
      }

}
0
Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

 
LVL 5

Expert Comment

by:twobitadder
ID: 10699284
You'll need to do a pre-parse/dbInsertion parse to compare every character for '/n' and sum them.
0
 
LVL 4

Author Comment

by:91mustang
ID: 10699508
thanks CEHJ
0
 
LVL 86

Expert Comment

by:CEHJ
ID: 10699524
8-)
0

Featured Post

Technology Partners: We Want Your Opinion!

We value your feedback.

Take our survey and automatically be enter to win anyone of the following:
Yeti Cooler, Amazon eGift Card, and Movie eGift Card!

Question has a verified solution.

If you are experiencing a similar issue, please ask a related question

For beginner Java programmers or at least those new to the Eclipse IDE, the following tutorial will show some (four) ways in which you can import your Java projects to your Eclipse workbench. Introduction While learning Java can be done with…
Are you developing a Java application and want to create Excel Spreadsheets? You have come to the right place, this article will describe how you can create Excel Spreadsheets from a Java Application. For the purposes of this article, I will be u…
Viewers learn about the “for” loop and how it works in Java. By comparing it to the while loop learned before, viewers can make the transition easily. You will learn about the formatting of the for loop as we write a program that prints even numbers…
Viewers learn how to read error messages and identify possible mistakes that could cause hours of frustration. Coding is as much about debugging your code as it is about writing it. Define Error Message: Line Numbers: Type of Error: Break Down…
Suggested Courses

739 members asked questions and received personalized solutions in the past 7 days.

Join the community of 500,000 technology professionals and ask your questions.

Join & Ask a Question