In Java simulate a vending machine that

Accepts bills of 1,5,10

Allow user to select products Water(1), Soda(2), Monster(3)

Allow user to take refund by canceling the request.

Needs generics and to implment an interface

Return selected product and remaining change if any....

This is what I have so far

public enum Product {

WATER("Coke", 1), SODA("Pepsi", 2), MONSTER("Soda", 3);

private String name;

private int price;

private Product(String name, int price) {

this.name = name;

this.price = price;

}

public String getName() {

return name;

}

public double getPrice() {

return price;

}

}

public class Inventory {

private HashMap inventory = new HashMap();

public int getQuantity(T product) {

Integer quanity = inventory.get(product);

return quanity == null ? 0 : quanity;

}

public void add(T product) {

int quanity = inventory.get(product);

inventory.put(product, quanity + 1);

}

public void deduct(T product) {

if (hasItem(product)) {

int quanity = inventory.get(product);

inventory.put(product, quanity - 1);

}

}

public boolean hasItem(T product) {

return getQuantity(product) > 0;

}

public void clear() {

inventory.clear();

}

public void put(T product, int quantity) {

inventory.put(product, quantity);

}

}