Reading content from text file into ArrayList using Java

Question

I'm facing a problem with moving content from file to ArrayList. The user selects a line from the file by an index which one he wants to add to ArrayList. I've tried with quick.add(new Pastatas()); But as I see it will add my empty constructor there.

private void myobj() {
    File FILE = new File(filex);
    if (FILE.exists() && FILE.length() > 0) {
        try {
            Scanner SC = new Scanner(FILE);
            for (int i = 0; i < FILE.length(); i++) {
                if (SC.hasNextLine()) {
                    String storage = SC.nextLine();
                    System.out.println("ID: " + i + " " + storage);
                }
            }
            System.out.println("select one.");
            Scanner sc = new Scanner(System.in);
            int userInputas = Integer.parseInt(sc.nextLine());
            for (int j = 0; j < FILE.length(); j++) {
                if (userInputas == j) {
                    quick.add(/*Probably problem here*/)
                }
            }
        } catch (IOException e) {
            System.err.println(e.getMessage() + "error");
        }
    }

Answer 1

Use the newer Path, Paths, Files for such tasks.

    Path path = Paths.get(filex);
    List<String> lines = Files.readAllLines(path);

    System.out.println("Select one.");
    Scanner sc = new Scanner(System.in);
    int lineno = Integer.parseInt(sc.nextLine()); // Maybe 1 based
    int index = lineno - 1; // Zero based index

    if (0 <= index && index < lines.size()) {
        String line = lines.get(index);
        System.out.println("Selected: " + line);
        quick.add(line);
    }

The error in the logic:

FILE (or Path above) is just a possibly not existing moniker/name for a file. The length is the number of bytes, the file size. So for a selection of a text line, one has to do something different, like opening, reading, and finally closing the file. The class Files provides utility functions to do such things as loading all lines.

---

After reading your comments; maybe something more like:

quick.add(new Pastatas(line));

In fact if the file is not a text file, we would need to know how the file was filled.