How to backup ArrayList in Java?

Question

I have some data stored as ArrayList. And when I want to backup this data,java bounds two objects forever. Which means when I change values in data ArrayL

Answer 1

Here is a fully functioning ArrayList backup class that checks if the ArrayList already exists. Basically it's just a for-loop cycling through the list and manually adding them to the new list.

import java.util.ArrayList;

public class Snapshot {
    private ArrayList dataBackup;

    public Snapshot(ArrayList data)
    {
        dataBackup = new ArrayList();
        for(int i = 0; i < data.size(); i++)
        {
            dataBackup.add(data.get(i));
        }
    }

    public ArrayList restore()
    {
        return dataBackup;
    }

    public static void main(String[] args)
    {
        ArrayList list = new ArrayList();
        list.add(1);
        list.add(2);

        Snapshot snap = new Snapshot(list);

        list.set(0, 3);
        list = snap.restore();

        System.out.println(list); // Should output [1, 2]

        list.add(4);
        list = snap.restore();

        System.out.println(list); // Should output [1, 2]
    }
}