Question

I have here a program that enters a paragraph and writes it into a file. After that, it should count the occurrences of each letters (case sensitive). However, it doesn’t count the number of letter occurrences. I think I put the for loop in the wrong place.

import java.io.*;
import java.util.*;
public class Exercise1 {

    public static int countLetters (String line, char alphabet) {
        int count = 0;
        for (int i = 0; i <= line.length()-1; i++) {
            if (line.charAt(i) == alphabet)
                count++;
        }
        return count;
    }

    public static void main(String[] args) throws IOException {
        BufferedReader buffer = new BufferedReader (new InputStreamReader(System.in));
        PrintWriter outputStream = null;
        Scanner input = new Scanner (System.in);
        int total;

        try {
            outputStream = new PrintWriter (new FileOutputStream ("par.txt"));
            System.out.println("How many lines are there in the paragraph you'll enter?");
            int lines = input.nextInt();
            System.out.println("Enter the paragraph: ");
            String paragraph = buffer.readLine();
            outputStream.println(paragraph);
            int j;
            for (j = 1; j<lines; j++) {
                paragraph = buffer.readLine();
                outputStream.println(paragraph);    
            }
            outputStream.close();
            System.out.println("The paragraph is written to par.txt");

            for (int k=1; k<lines; k++) {
                paragraph = buffer.readLine();
                total = countLetters (paragraph, 'A');
                if (total != 0)
                    System.out.println("A: "+total);
                            //I'll do bruteforce here up to lowercase z

            }
        }

        catch(FileNotFoundException e) {
            System.out.println("Error opening the file par.txt");
        }

    }

}

Please help me fix the code. I’m new in programming and I need help. Thank you very much!

Answer 1

First, your initial reading user input is a bit of a waste since you read once then enter the for loop for the rest – this is not a problem, just a better code.

// your code
String paragraph = buffer.readLine();
outputStream.println(paragraph);
int j;
for (j = 1; j<lines; j++) {
     paragraph = buffer.readLine();
     outputStream.println(paragraph);    
 }

You can just put them in the loop:

// better code
String paragraph;
int j;
for (j = 0; j<lines; j++) {
     paragraph = buffer.readLine();
     outputStream.println(paragraph);    
}

Then your first problem comes from the way you read the lines:

// your code - not working
outputStream.close();
for (int k=1; k<lines; k++) {
      paragraph = buffer.readLine();
      total = countLetters (paragraph, 'A');

Consider what happened above:

• The input is already DONE, the output is already written and stream is closed – up to here everything is good
• Then when you try to count the number of characters, you do: paragraph = buffer.readLine(); – what does this code do? It waits for another user input (instead of reading what’s been inserted)

To fix the problem above: you need to read from what’s already been written – not asking for another input. Then instead of brute forcing every character one by one, you can just put them into a list and write a for loop.

So now, you want to read from the existing file that you already created (ie. reading what WAS inputted by the user):

BufferedReader fileReader = new BufferedReader(new FileReader(new File("par.txt")));

String allCharacters = "abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ";
String aLineInFile;

// Read the file that was written earlier (whose content comes from user input)
// This while loop will go through line-by-line in the file
while((aLineInFile = fileReader.readLine()) != null)
{
      // For every line in the file, count number of occurrences of characters  
      // This loop goes through every character (a-z and A-Z)  
      for(int i = 0; i < allCharacters.length(); i++)
      {
            // For each single character, check the number of occurrences in the current line
            String charToLookAt = String.valueOf(allCharacters.charAt(i));
            int numOfCharOccurancesInLine = countLetters (aLineInFile, charToLookAt);

            System.out.println("For line: " + aLineInFile + ", Character: " + charToLookAt + " appears: " + numOfCharOccurancesInLine + " times " );
      }         
}

The above gives you the number of occurrences of every character in every line – now you just need to organize them to keep track of how many are in total for the whole file.

Code-wise, there might be better way to write this to have cleaner implementation, but the above is easy to understand (and I just wrote it very quickly).