CODEWITHSUNDEEP
javatextline-numbers
Sangeet Menon
Sangeet Menon

Reputation: 9905

Count the number of lines in a text file while its still being written

I have a java program that creates a text file as follows:

FileWriter fstream = new FileWriter(filename + ".txt");
BufferedWriter outwriter = new BufferedWriter(fstream);

I add lines to the file by using 

outwriter.write("line to be added");

Now at certain stages of the program I need to know how many lines I have added in the text file, while the file still has lines waiting to be added.

This whole process is to add some footer and header.

Is there any method that can find the current or last added line number?

EDIT

Adding a function or a counter to add lines is a solution but the time constraint doesn't allow me that. As I am dealing with hell lot of LOC this would be a major change at a lot of places it would consume a lot of time.

Upvotes: 1

Views: 3977

Answers (5)

JREN
JREN

Reputation: 3630

Create a method like this:

public int writeLine(BufferedWriter out, String message, int numberOfLines) {
    out.write(message);
    return numberOfLines++;
}

Then you can do this:

int totalLines = 0;
totalLines = writeLine("Line to be added", outwriter, totalLines);

System.out.println("Total lines: " + totalLines);

> "Total lines: 1"

Upvotes: 0

asifsid88
asifsid88

Reputation: 4701

Make a method which will write lines to the files 

private static int lineCount;
private static void fileWriter(BufferedWriter outwriter, String line)
{
    outwriter.write(line);
    lineCount++;
}

Now each time you need to write a line to a file, then just call this method. And at any point in time you need to know the line count then lineCount variable will do the concern.

Hope this helps!

Upvotes: 0

AlexR
AlexR

Reputation: 115328

Sure. Just implement your own writer, e.g. LineCountWriter extends Writer that wraps other Buffered and counts written lines.

Upvotes: 1

Brian Agnew
Brian Agnew

Reputation: 272237

Take a look at Apache Commons Tailer.

It will perform a tail-like operation and call you back (via TailListener) for each line as lines are added to the file. You can then maintain your count in the callback. You don't have to worry about writing file reading/parsing code etc.

Upvotes: 2

surfealokesea
surfealokesea

Reputation: 5116

Make a counter:

lineCounter+="line to be added".split("\n").length-1

Upvotes: 0

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