Java - How Can I Write My ArrayList to a file, and Read (load) that file to the original ArrayList?

Question

I am writing a program in Java which displays a range of afterschool clubs (E.G. Football, Hockey - entered by user). The clubs are added into the following ArrayList<

Answer 1

You should use Java's built in serialization mechanism. To use it, you need to do the following:

1. Declare the Club class as implementing Serializable:

   public class Club implements Serializable {
       ...
   }
   

   This tells the JVM that the class can be serialized to a stream. You don't have to implement any method, since this is a marker interface.

2. To write your list to a file do the following:

   FileOutputStream fos = new FileOutputStream("t.tmp");
   ObjectOutputStream oos = new ObjectOutputStream(fos);
   oos.writeObject(clubs);
   oos.close();
   

3. To read the list from a file, do the following:

   FileInputStream fis = new FileInputStream("t.tmp");
   ObjectInputStream ois = new ObjectInputStream(fis);
   List clubs = (List) ois.readObject();
   ois.close();