private void addSave(Customer customer){
       ArrayList<Customer> customers = new ArrayList<>();
    
       try
        {
            FileInputStream fis = new FileInputStream("customerfile");
            ObjectInputStream ois = new ObjectInputStream(fis);
            customers = (ArrayList) ois.readObject();
            ois.close();
            fis.close();
         }catch(IOException ioe){
             ioe.printStackTrace();
             return;
          }catch(ClassNotFoundException c){
             System.out.println("Class not found");
             c.printStackTrace();
             return;
          }
       for(Customer tmp: customers){
            System.out.println(customer.toString());
        }
     
         customers.add(customer); 
     try{
         FileOutputStream fos= new FileOutputStream("customerfile");
         ObjectOutputStream oos= new ObjectOutputStream(fos);
         oos.writeObject(customers);
         oos.close();
         fos.close();
       }catch(IOException ioe){
            ioe.printStackTrace();
        }     
         
    }