Generate name of array with a loop java

You don't have to give names, just add new Brunch directly

order.add(new Brunch("Brunch", 199));
order.add(new Brunch("Vodka", 99));
order.add(new Brunch("Whisky", 1199));

If you want go list all the keys, then this will work.

Map<String, ArrayList<SellAbleItems>> orders = new HashMap<>();
orders.put("orderA", order1);
orders.put("orderB", order2);

Set<String> keys = orders.keySet();
for(int i = 0; i < orders.size(); i++) {
  System.out.println(keys.toArray()[i]);
}

Prints:

orderA
orderB

You don't need to know how many orders a user creates before you create your map but you will need to know when a user creates a new Order. Once you know that you can add a Map to hold your orders like this:

// Program initiates
Map<String, ArrayList<SellAbleItems>> orders = new HashMap<>();

// User places order 1
List<SellAbleItems> order1 = new ArrayList<>();
order1.put(Vodka);
order1.put(Brunch);
orders.put("order1", order1);

// Some time later user places order 2
List<SellAbleItems> order2 = new ArrayList<>();
order2.put(Foo);
order2.put(Bar);
orders.put("order2", order2);

You can then loop through the Map as described here: Iterate through a HashMap

A better abstraction would be to create an Order class that has a List to which you can Add your SellAbleItem and then you can keep a List<Order> instead but that would be a different question.