How to count the number of characters in a line in a csv file

Question

I have a Justice_League.csv file that has four lines with commas between them. I want to count the number of characters there are in each line and convert that number to hex.

Below is the contents of Justice_League.csv:

Bruce Wayne,Batman,None,Gotham City,Robin,The Joker                 43      2B
Oliver Queen,Green Arrow,None,Star City,Speedy,Deathstroke          50      32
Clark Kent,Superman,Flight,Metropolis,None,Lex Luthor               46      2E
Bart Allen,The Flash,Speed,Central City,Kid Flash,Professor Zoom    52      34

As you can see I have handcounted the characters and wrote the HEX value next to it. Now I need this done in Java. This is what I have so far. Can anybody help me out?

public String convertCSVToFlat (Exchange exchange) throws Exception {
    String csv="Justice_League.csv";
    BufferedReader bReader = new BufferedReader(new FileReader(csv));
    String line = "";
    int count = 0;
    String str[] = new String[200];
    int[] a = new int[24];
    String[] hexNumber = new String[4];
    try {
        bReader.readLine();
        int characterSum = 0;
        int i = 0;  
        while((line = bReader.readLine()) != null) {
             String[] f=line.split(",");
             a[count]=Integer.parseInt(f[2]);
             str[count]=f[1];            
             count++;
             characterSum += line.length();
             hexNumber[i] = Integer.toHexString(characterSum);
             i++;
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
    bReader.close();
    return hexNumber.toString();

Answer 1

I suggest you to read the javadoc of String.split. I think that you misunderstood the concept when you did this:

String[] f=line.split(",");

a[count]=Integer.parseInt(f[2]); //--> java.lang.NumberFormatException here!

Avoid using 'magic' numbers in your code like int[] a = new int[24];. Why 24?

Well, here comes a version that do what you want to do. Maybe it isn't the best way to do this but it works.

public void convertCSVToFlat () throws Exception {
    String csv="Justice_League.csv";
    BufferedReader bReader = new BufferedReader(new FileReader(csv));
    
    //We're storing the values at this 3 arraylists, 
    //but a better approach is using an object to hold'em
    ArrayList<String> lines = new ArrayList<String>();
    ArrayList<Integer> chars = new ArrayList<Integer>();
    ArrayList<String> hex = new ArrayList<String>();
    
    String line = "";
    try {
        while((line = bReader.readLine()) != null) {
            lines.add(line);
            //I'm assuming that you don't want to count the commas and spaces.
            //If you want to, comment the next line
            line = line.replaceAll(",", "").replaceAll(" ", "");
            int c = line.length(); //count remaining chars...
            chars.add(c);
            hex.add(Integer.toHexString(c));
        }
    } catch (IOException e) {
        e.printStackTrace();
    }
    bReader.close();
    
    //Just to show the results
    for (int i = 0; i < lines.size(); i++) {
        System.out.print(lines.get(i));
        System.out.print("\t" + chars.get(i));
        System.out.println("\t" + hex.get(i));
    }
}

Like I said previously, this is a way to solve this. You should try another options to solve this in order to improve your knowledge...