[ksmith11]

When you have an input file and you want to use a BufferedReader to count the number of lines and return it, would you use

public static int countLines (BufferedReader in) throws IOExceptions
BufferedReader inputFile =new BufferedReader(new FileReader("in.txt"));
int lines = inputFile.readLine();

if so then what do you use after that to continue to the next line and so on?

[Martyr2]

Typically you would setup a while loop and instead of setting int countlines to the line read, you would set countlines before the loop starts to 0 and for each read line you would increment the int count. Below is an example of how you would do this...

import java.io.*;

public class countlines {
	public static void main(String args[]) {
		// Setup your counter
		int countlines = 0;

		try {
			BufferedReader inputFile = new BufferedReader(new FileReader("c:\\test.txt"));
			String line = "";

			// For each line read, increment the counter
			while ((line = inputFile.readLine()) != null) {
				countlines++;
			}
		
			inputFile.close();


			// Print the number of lines
			System.out.println("Number of lines is: " + countlines);
		}
		catch (Exception e) {
			System.out.println("Error: " + e.getMessage().toString());
		}
	}
}

As you can see I setup a while loop that just reads each line using readline and increment the count. At the end I have the number of lines. You can of course adapt this to your function and return countlines.

Enjoy!

"At DIC we be line counting code ninjas... 1...2...3...6..4...9.. crap I lost count"

[ksmith11]

thanks man .. one more question.

what about if you want to read integers on several lines and then output the sum of them.

[Martyr2]

That is the beauty of this solution, each line is being read and stuck into the variable "line" in my example. Simply parse the line into an integer (using Integer.parseInt) and add it to a variable you have defined before the start of the loop. Once the loop is finished you have everything you need for the sum and even the average (this is given that each line is a single number).

sum variable / countlines = average

Now of course if each line has multiple integers, then you will need a loop inside the while loop to reach each number in the single line and sum them together.

The key is the while loop reading each line. It counts by incrementing countlines but also provides you access to the line read using the line variable.

[ksmith11]

alright thanks a bunch

[ksmith11]

nevermind

This post has been edited by ksmith11: 20 May 2008 - 04:25 PM