Count the lines of a file

Question

I have a question about Java:

I am trying to make a program that goes through files and checks something, but for that I need something to count the lines, does anyone knows a good method to do this?

I have never worked with files before so I dont really know something. Also I don't have code to show, because I don't know how to do it.

inform yourself about java IO streams https://docs.oracle.com/javase/tutorial/essential/io/streams.html — Kristijan Iliev, Jul 16 '15 at 06:58

JetStream · Accepted Answer · 2015-07-16T07:01:51.303

3

By searching on the Internet you could have found this by yourself. But nevertheless, here is a code that I use:

    public static int countLines(String filename) throws IOException {
        InputStream is = new BufferedInputStream(new FileInputStream(filename));
        try {
            byte[] c = new byte[1024];
            int count = 0;
            int readChars = 0;
            boolean empty = true;
            while ((readChars = is.read(c)) != -1) {
                empty = false;
                for (int i = 0; i < readChars; ++i) {
                    if (c[i] == '\n') {
                        ++count;
                    }
                }
            }
            return (count == 0 && !empty) ? 1 : count;
        } 
        finally {
            is.close();
        }
    }

I hope it works for you.

Update:

This should be easier for you.

BufferedReader reader = new BufferedReader(new FileReader(file));
int lines = 0;
while (reader.readLine() != null) lines++;
reader.close();
System.out.println(lines);

edited Jul 16 '15 at 07:01

answered Jul 16 '15 at 06:52

JetStream

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Well, that was really fast, thank you! It seems to work (testet it shortly in the main method). – Dogyman Jul 16 '15 at 06:54
This is a really poor and convoluted way to count lines. I'd imagine doing something like this back when I was writing Java 1.2, but even then I'd use a `BufferedReader`. The only advantage here is that you can't break it with long lines (I'm talking 2GB or so), but that's rarely an issue. – Kayaman Jul 16 '15 at 07:02
@Kayaman Still it works so I'm going to use it, I will test both methods but both seem to be right :D – Dogyman Jul 16 '15 at 07:05
@Kayaman Yeah I know that this method is old but I still use it, don't ask me why its just preferred by me – JetStream Jul 16 '15 at 07:08

marstran · Answer 2 · 2015-07-16T07:22:01.823

1

In Java 8:

long lineCount = 0;

try (Stream<String> lines = Files.lines(Paths.get(filename))){
    lineCount = lines.count();
} catch (final IOException i) {
    // Handle exception.
}

edited Jul 16 '15 at 07:22

answered Jul 16 '15 at 06:55

marstran

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Thank you but I dont want to use Java 8, because it isn't used that often yet :D – Dogyman Jul 16 '15 at 06:56
1

`Files.lines()` should be opened in a try-with-resources statement! – fge Jul 16 '15 at 07:03
1

@Dogyman Java 8 is seeing very rapid adoption; you'd better get used to it very soon! – fge Jul 16 '15 at 07:03
@fge That is very true! Fixed. – marstran Jul 16 '15 at 07:19

score 0 · Answer 3 · answered Jul 16 '15 at 06:54

You can try this, in lines variable you will get number of lines.

 public String getFileStream(final String inputFile) {
            int lines = 0;
            Scanner s = null;

            try {
                s = new Scanner(new BufferedReader(new FileReader(inputFile)));
                while (s.hasNext()) {
                   lines++;
                }
            } catch (final IOException ex) {
                ex.printStackTrace();
            } finally {
                if (s != null) {
                    s.close();
                }
            }
            return result;
    }

score 0 · Answer 4 · answered Jul 16 '15 at 07:01

Simply you can do this :-

        BufferedReader br = new BufferedReader(new FileReader(FILEPATH));
        int lineCount = 0;
        while(br.readLine() != null)
            lineCount++;
        System.out.println(lineCount);

BufferedReader class provides readLine() which reads the text line-by-line so this can be used to get the lines count.

score 0 · Answer 5 · answered Jul 16 '15 at 07:02

you can do simply :

public static void main(String[] args) {

    int linecount = 0;

    try {
        // Open the file
        FileInputStream fstream = new FileInputStream("d:\\data.txt");
        BufferedReader br = new BufferedReader(new InputStreamReader(
                fstream));
        String strLine;
        // Read File Line By Line
        while ((strLine = br.readLine()) != null) {
            if (strLine.trim().length() > 0) { // check for blank line
                linecount++;
            } else {
                continue;
            }
        }

        System.out.println("Total no. of lines = " + linecount);
        // Close the input stream
        br.close();
    } catch (Exception e) {
        // TODO: handle exception
    }

}

Count the lines of a file

5 Answers5