How to sort and rearrange the file data in Java?

Question

I have a txt file saved in this format:

806PYZnmNaw4h0wh8fyWDQ 0 0 0 0 0 1 0 
bvu13GyOUwhEjPum2xjiqQ 0 0 0 1 0 0 0 
kDUEcqnK0MrjH9hcYHDKUw 1 0 1 0 0 0 0 
806PYZnmNaw4h0wh8fyWDQ 1 0 1 0 0 0 0 
bvu13GyOUwhEjPum2xjiqQ 0 1 1 1 1 0 0 
tvCT2yT3bLlpU2crUt0zJw 1 0 0 1 0 0 0 
806PYZnmNaw4h0wh8fyWDQ 1 1 1 0 0 0 0 
9Ify25DK87s5_u2EhK0_Rg 0 0 0 1 0 0 0 
bvu13GyOUwhEjPum2xjiqQ 0 1 0 1 0 0 0 
806PYZnmNaw4h0wh8fyWDQ 1 0 0 0 0 0 0 
zk0SnIEa8ju2iK0mW8ccRQ 0 0 0 0 1 0 0 
AMuyuG7KFWJ7RcbT-eLWrQ 0 0 0 1 0 0 0

Now I need to loop through this input file and save a sorted and rearranged output file based on first encoded value which can occur more than once in the input file? For eg in this example file, I have 806PYZnmNaw4h0wh8fyWDQ more than once in random places.

This is so far I tried: private static final String Path = "newuserfeature.txt";

public static void main(String[] args) {
    List<String> list = new ArrayList<String>();
    List<String> uniquelist = new ArrayList<String>();
    try {

        Scanner unique = new Scanner(new FileReader(Path));

        while (unique.hasNextLine()) {
            String userUnique = unique.nextLine();
            uniquelist.add(userUnique);
        }

        Iterator<String> it = uniquelist.iterator();

        while (it.hasNext()) {
            String user = it.next();
            int a = 0;
            int b = 0;
            int c = 0;
            int d = 0;
            int e = 0;
            int f = 0;
            int g = 0;

            Iterator<String> it2 = list.iterator();
            while (it2.hasNext()) {
                String[] y = it2.next().toString().split(" ");
                if (user.equalsIgnoreCase(y[0])) {
                    int a1 = Integer.parseInt(y[1]);
                    int b1 = Integer.parseInt(y[2]);
                    int c1 = Integer.parseInt(y[3]);
                    int d1 = Integer.parseInt(y[4]);
                    int e1 = Integer.parseInt(y[5]);
                    int f1 = Integer.parseInt(y[6]);
                    int g1 = Integer.parseInt(y[7]);

                    if (a1 == 1) {
                        a = a1;
                    }
                    if (b1 == 1) {
                        b = b1;
                    }
                    if (c1 == 1) {
                        c = c1;
                    }
                    if (d1 == 1) {
                        d = d1;
                    }
                    if (e1 == 1) {
                        e = e1;
                    }
                    if (f1 == 1) {
                        f = f1;
                    }

                }

            }
            System.out.println(user + " " + a + " " + b + " " + c + " " + d
                    + " " + e + " " + f + " " + g + "\n");
        }

    } catch (FileNotFoundException e) {
        e.printStackTrace();
    }
}

Answer 1

If you are only sorting the lines by the first field which happens to be a string, you can you just do:

Path oldFile = Paths.get("/path/to/my/file");
Path newFile = Paths.get("/path/to/my/newFile");

List<String> lines = Files.readAllLines(oldFile);
Collections.sort(lines);
Files.write(newFile, lines);

which:

1: load all lines in a list of strings,
2: sort by string (which is what you want at the end of the day)
3: store the lines in another file

As you are doing a string sorting by the first field, you don't need to break down each line into its columns.