Question

Here is my code:

public boolean readFromFileBooking()
    {
       boolean isFileBooking = true;
        try 
        {
            BufferedReader reader = new BufferedReader(new FileReader("bookings.txt"));   
            String data = reader.readLine();   
            if (data == null)   
            {
                System.out.println("No Bookings Have Been Made . . . .");
            }    
 data = reader.readLine();  
 reader.close();            
}

Here is the sequence:

1. Write array into a text file
2. Stop/exit from the system
3. On restart load the previous array in the text file so it can be used again.

The problem is whenever I start a new system, the text file will be overwritten by a new array. Actually I want the new array become a new list in ArrayList.

Can you guys share to me how to load the previous data in a new system? How to load/copy the previous data in text file?

Answer 1

This will write out an array of integers into a file with each number separated by a space. It will then read them back in and store them as an arraylist. I have ignored the exception handling to focus on the IO.

public static void main(String[] args) {
    int[] array = { 1, 2, 3 };
    writeOut(array);
    List<Integer> list = readIn();
    for (Integer num : list) {
        System.out.print(num + " " );
    }
}

public static List<Integer> readIn() {
    final File file = new File("file.txt");
    List<Integer> list = new ArrayList<Integer>();
    Scanner scan;
    try {
        scan = new Scanner(file);
        while (scan.hasNextInt()) {
            list.add(scan.nextInt());
        }
    } catch (FileNotFoundException e) {
    }
    return list;
}

public static void writeOut(int[] array) {
    final File file = new File("file.txt");

    try {
        file.createNewFile();
        final FileWriter writer = new FileWriter(file);

        for (int i = 0; i < array.length; i++) {
            writer.write(Integer.toString(array[i]) + " ");
        }
        writer.close();
        writer.flush();
    } catch (final IOException e) {
    }
}