The Q3 shape

Q3 hands you a provided class and asks you to write ONE method — the whole question is that method. The list usually holds objects:

// provided:
public class Order {
    private String customer;
    private int cents;
    public Order(String c, int cents) { customer = c; this.cents = cents; }
    public String getCustomer() { return customer; }
    public int getCents() { return cents; }
}
// to write: total for one customer
public int customerTotal(ArrayList<Order> orders, String name) { ... }

The Q3 playbook is three verbs:

• count — how many orders belong to "Ana"? (filter + counter)
• match — find the first/last order matching a condition (filter + sentinel)
• process — aggregate or transform (filter + accumulator)

Every Q3 answer is a for-each (reading) or indexed loop (mutating) plus one machine. The wrapper class changes; the machines never do. The exam's twist is usually in the specification prose: "adjacent duplicates count once", "orders before the first rejection only", "ties broken by earliest" — underline those phrases; they are the obligations that separate 6 from 9.