Question

I want to save values as an ArrayList of double in a file. Whenever there is new value, it should be added in an ArrayList without erasing the previous ones. I’m try to use the function,DataStream. Is it possible? If its possible, please let me know how to implement that.

Answer 1

Please refer below code .

    private static String LFILE = "serial";

public static void updateFile(Double num) {

    FileOutputStream fos = null;
    ObjectOutputStream oos = null;

    try{
        List<Double> list = getDoubles();
        list.add(num);
        fos = new FileOutputStream(LFILE);
        oos = new ObjectOutputStream(fos);
        oos.writeObject(list);

    }catch(Exception e){
        e.printStackTrace();
        try {
            oos.close();
            fos.close();
        } catch (IOException e1) {
            e1.printStackTrace();
        }

    }

}

public static List<Double> getDoubles() {

    FileInputStream fis = null;
    ObjectInputStream ois = null;
    List<Double> newList = new ArrayList<Double>();
    try {
        fis = new FileInputStream(LFILE);
        ois = new ObjectInputStream(fis);

        newList = (ArrayList<Double>) ois.readObject();

    } catch (Exception ex) {

        try {
            fis.close();
            ois.close();
        } catch (IOException e) {
            e.printStackTrace();
        }
    }
    return newList;
}