Remove StringBuilder appends before saving arraylist

Question

I'm going through the following steps and I'm having an issue when saving the original file.

1. Read file to objects
2. Add objects to arraylist
3. override toString method for printing to console
4. save file repeat.

The issue is repeating as the file layout has now changed. I'm trying to find a method to print to the file without all of the appends.

I've looked into 2 different ways, ignore words while reading, and trying to remove the words before saving. Both of which seemed really messy and confusing.

Here is my StringBuilder:

    @Override
public String toString() {
    StringBuilder builder = new StringBuilder();
    builder.append("Room Number: ").append(roomNumber);
    builder.append(", Room Type: ").append(roomType);
    builder.append(", Room Price: £").append(format.format(roomPrice));
    builder.append(", Room Balcony: ").append(roomBalcony);
    builder.append(", Room Lounge: ").append(roomLounge);
    builder.append(", Room Reserved by: ").append(reservedBy);
    builder.append("\n");
    return builder.toString();
}

Here is my filescanner

        while (file.hasNextLine()) {
        int roomNumber = file.nextInt();
        String roomType = file.next();
        double roomPrice = file.nextDouble();
        boolean roomBalcony = file.nextBoolean();
        boolean roomLounge = file.nextBoolean();
        String reservedBy = file.next();
        roomList.add(new Room(roomNumber, roomType, roomPrice, roomBalcony, roomLounge, reservedBy));
    }

Answer 1

I think I know what you are asking. You implemented a toString() that's useful for console print-outs but not for writing data to your files. This is fine, and not unusual. In your code, you're using toString() for informative/UI purposes, so you'll just have to not use toString() when you're saving it to a file.

So just... save it to the file another way. It's pretty much that simple.

You could for example add a function that builds a string you can save, like:

public String toFileString () {
    return the line you'd write to a file;
}

Then

ArrayList<MyThings> things = ...;

for (MyThing thing : things) 
    outputFile.println(thing.toFileString());

Or you could write a function that writes to a PrintWriter (or some other Writer but PrintWriter has a lot of convenient methods), for example:

void saveTo (PrintWriter out) {
    // print a line to out
}

Then:

for (MyThing thing : things) 
    thing.saveTo(outputPrintWriter);

Or you could make your object have no knowledge of files at all and instead just write out its stuff explicitly when saving:

for (MyThing thing : things) {
    out.print(thing.getRoomNumber());
    // and so on...
}

Or whatever. There's a million options, point being, just don't save with toString(), save with something else.