Replacing an exact character in a string out of a file?

Question

I'm making a program that fixes a separator in csv file, and my idea was read all the lines, then check each line for the wrong separator, then replace it with the good one. I've been trying multiple things, but this is where I'm stuck right now. This is the code:

try (FileWriter escritor = new FileWriter(archivoRes.getAbsoluteFile()); BufferedReader lectorArchivo = new BufferedReader(new FileReader(archivoSelec)); BufferedWriter bfw = new BufferedWriter(escritor)) {

    byte[] byteArray = new byte[(int) archivoSelec.length()];
    FileInputStream fis = new FileInputStream(archivoSelec);
    fis.read(byteArray);

    int count = 1;
    for (int i = byteArray.length; i >= 0; i--) {
        String line = lectorArchivo.readLine();
        if (line.indexOf(":") == 82 || line.indexOf(":") == 68 || line.indexOf(":") == 81) {
            line.replaceFirst(":", ";");

        }
        bfw.write(line);
        bfw.newLine();
    }


    bfw.close();

} catch (IOException e) {
    System.err.format("IOException: %s%n", e);
}

Any ideas on how I could get this through?

UPDATE:

I've discovered StringTokenizer, which seems easier, but I can't still get it working. This is the code at the moment.

for(int i = byteArray.length;i >= 0;i--){
                    String line = lectorArchivo.readLine();
                    StringTokenizer token = new StringTokenizer(line, ";");

                    if (token.countTokens() == 3) {
                        line.replaceAll(separador_old, separador);


                    }
                    bfw.write(line);
                    bfw.newLine();

                }


                bfw.close();

But what is the problem? Does your code work? Does it produce some errors? What is expected vs actual output? — Amongalen, Feb 20 '20 at 11:50
The full code works, it reads the origin file and rewrite it into the one I want, but the separator remains unchanged. — Cpt-Proxy, Feb 20 '20 at 11:52
What is `if (line.indexOf(":") == 82 || line.indexOf(":") == 68 || line.indexOf(":") == 81)` supposed to do? Do you want to replace `:` only if it appears at those specific indices? — Amongalen, Feb 20 '20 at 11:53
Yes, since other separators that are correct exist beyond those points. — Cpt-Proxy, Feb 20 '20 at 11:54
Strings in Java are immutable. `line.replaceFirst(":", ";");` returns a new String. It does not change the current String (line). You need to change this line to `line = line.replaceFirst(":", ";");` — sudhir shakya, Feb 20 '20 at 12:51

score 1 · Answer 1 · answered Feb 20 '20 at 12:49

1

String is immutable.

line.replaceFirst(":", ";"); does not do anything.

You need to assign the result somewhere.

Maybe back to line?

answered Feb 20 '20 at 12:49

Thilo

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Just did, didn't change anything. Although thanks for the tip. – Cpt-Proxy Feb 20 '20 at 12:52
replace `line.replaceAll(separador_old, separador);` with `line = line.replaceAll(separador_old, separador);` – xxlali Feb 20 '20 at 12:56

Replacing an exact character in a string out of a file?

1 Answers1