Question

It’s not that my code doesn’t work, but I am doubting whether it’s very efficient or not. My theory is, that it isn’t xD

I have a JTextPane where I have to take the text in it (Making a new line every time the JTextPane got a new line basically), and put it into a .txt file. As I said everything works but I am doubting the implementation of it.
This is the part I am doubting:

public void printLog() {
    String s = logTextArea.getText();
    ArrayList<String> log = new ArrayList<>();
    StringBuilder sb = new StringBuilder();
    for(int i = 0; i < s.length(); i++) {
        if(s.charAt(i) != '\n') {
            sb.append(s.charAt(i));
        } else {
            log.add(sb.toString());
            sb.delete(0, sb.length());
        }
    }

This is the entire thing just for reference:

public void printLog() {
    String s = logTextArea.getText();
    ArrayList<String> log = new ArrayList<>();
    StringBuilder sb = new StringBuilder();
    for(int i = 0; i < s.length(); i++) {
        if(s.charAt(i) != '\n') {
            sb.append(s.charAt(i));
        } else {
            log.add(sb.toString());
            sb.delete(0, sb.length());
        }
    }
    File f = new File("JServer_Log.txt");
    BufferedWriter bw = null;
    FileWriter fr = null;
    try {
        if(f.exists()) {
            fr = new FileWriter(f,true);
        } else {
            fr = new FileWriter(f);
        }
    } catch (IOException e) {
        // Nothing to do really.
    }

    try {
        bw = new BufferedWriter(fr);
        Iterator<String> itr = log.iterator();
        bw.newLine();
        while(itr.hasNext()) {
            bw.write(itr.next());
            bw.newLine();
        }
    } catch (IOException e) {
        // Nothing to do really. We lost the log?
    } finally {
        try {
            bw.close();
        } catch(IOException ioe) {
            // The program is closing any way.
        }
    }
}

Answer 1

It seems that you just need to make sure you use the platform’s appropriate newline sequence. You can just say s = s.replace("\n", System.getProperty("line.separator")) and then write that whole string directly to file. In fact, the way I see it, this is all the code you need (except maybe for exception handling, up to you):

public void printLog() throws IOException {
  final FileWriter w = new FileWriter("JServer_Log.txt", true);
  try {
    w.write(logTextArea.getText().replace("\n", 
                                    System.getProperty("line.separator")));
  } finally { w.close(); }
}