Writing into text file from ArrayList that has multiple values per ArrayList object (java)

Question

I am trying to save my ArrayList into a text file. But the format of how it is saved is wrong. My code:

ArrayList<Vehicle> vehs = new ArrayList<Vehicle>();

vehs.add(new Vehicle("QJT123", "Starlet 99", 35.0, 190000));
vehs.add(new PremiumVehicle("TUX132", "BWM 05  ", 90.0, 12000, 100, 10000, 5000));

Constructor used for these 2:

public PremiumVehicle(String vehicleID, String description, double dailyRate, int odometer, int allowance, int serLength, int lastOdo) //subclass

public Vehicle(String vehicleID, String description, double dailyRate, int odometer) //Superclass

Both of these are stored into the Vehicle ArrayList. Code to save to text file:

private static void saveFile(ArrayList<Vehicle> vehs){
    File fileName = new File("VehicleList.txt");        

    try {
        FileWriter fw = new FileWriter(fileName);
        Writer output = new BufferedWriter(fw);

        for (int i = 0; i < vehs.size(); i++){
            output.write(vehs.get(i).toString() + "\n");
        }

        output.close();

    } catch (Exception e) {
        JOptionPane.showMessageDialog(null, "I cannot create that file");
    }
}

My output in VehicleList.txt:

vehicle ID = QJT123 Description = Starlet 99    Status = A  Daily Rate = 35.0 Odometer reading = 190000vehicle ID = TUX132  Description = BWM 05    Status = A  Daily Rate = 90.0   Odometer reading = 12000 Mileage allowance = 100    service length = 10000  Last Service = 5000

How do i make it such that each new line is added when writing in a new ArrayList object, e.g:

vehicle ID = QJT123 Description = Starlet 99    Status = A  Daily Rate = 35.0 Odometer reading = 190000
vehicle ID = TUX132 Description = BWM 05    Status = A  Daily Rate = 90.0   Odometer reading = 12000 Mileage allowance = 100    service length = 10000  Last Service = 5000

I've tried using vehs.get(i).toString() + "\n" but it doesn't seem to work.

not clear for me, your 2 objects are getting written in the same line??? — ΦXocę 웃 Пepeúpa ツ
– ΦXocę 웃 Пepeúpa ツ, Commented May 24, 2017 at 9:46
@ΦXocę웃Пepeúpaツ yes, in my text file, it is all written in one line. A new line is suppose to be added right before vehicle ID — Dario Ongsono
– Dario Ongsono, Commented May 24, 2017 at 9:49
doesn't make any sense. tested with some code and it works perfectly fine — XtremeBaumer
– XtremeBaumer, Commented May 24, 2017 at 9:49

GhostCat · Accepted Answer · 2017-05-24 09:55:44Z

2

Most likely, your platform does not see \n as a newline character - that thing depends on the OS.

One way to obtain the correct newline marker:

String lineSep = System.getProperty("line.separator");

or even simpler:

String lineSep = System.lineSeparator();

and instead of using + "\n" you do + lineSep in your code.

edited May 24, 2017 at 9:55

answered May 24, 2017 at 9:52

GhostCat

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1 Comment

ΦXocę 웃 Пepeúpa ツ Over a year ago

or even better System.lineSeparator()

Arnaud · Accepted Answer · 2017-05-24 09:51:07Z

1

BufferedWriter has a newLine() method, you may use that if you declare output as a BufferedWriter .

private static void saveFile(ArrayList<Vehicle> vehs){
    File fileName = new File("VehicleList.txt"); 


    try {
        FileWriter fw = new FileWriter(fileName);
        BufferedWriter output = new BufferedWriter(fw);

        for (int i = 0; i < vehs.size(); i++){
            output.write(vehs.get(i).toString());
            output.newLine();
        }

        output.close();

    } catch (Exception e) {
        JOptionPane.showMessageDialog(null, "I cannot create that file");
    }
}

Also for the javadoc of the method :

Writes a line separator. The line separator string is defined by the system property line.separator, and is not necessarily a single newline ('\n') character.

edited May 24, 2017 at 9:51

answered May 24, 2017 at 9:49

Arnaud

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5 Comments

XtremeBaumer Over a year ago

\n should work in his code. at least it does for me

Arnaud Over a year ago

It is platform-dependent .

Dario Ongsono Over a year ago

@XtremeBaumer yeah.. somehow \n isn't working for me.

XtremeBaumer Over a year ago

@Berger with \n\r it should work on every common OS right?

Arnaud Over a year ago

@XtremeBaumer : well indeed with \r\n it should match the common system's new line sequences (\r\n, \r, \n ) .

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