class VendingMachine extends AnyRef
The class VendingMachine
can be used to simulate simple virtual soda vending
machines. A vending machine sells bottles of a single type of soft drink at a
certain price per bottle.
The methods of the class correspond to the actions of buyers and maintenance
personnel on an actual vending machine. For instance, a purchase is made by
first inserting some money possibly several times with each one adding to the
previous insertion, and then selecting to buy a bottle. This interaction is
captured by the methods insertMoney
and buyBottle
.
Some of the methods are illustrated in the following REPL session, in which the vending machine initially contains 10 bottles with a price of 250 cents (2.5 euros) each:
INPUT: val machine = new VendingMachine(250, 10) OUTPUT: machine: o1.soda.VendingMachine = earned 0.0 euros, inserted 0 cents, 10 bottles left INPUT: machine.insertMoney(300) INPUT: "got change: " + machine.sellBottle() OUTPUT: res0: String = got change: 50 INPUT: machine OUTPUT: res1: o1.soda.VendingMachine = earned 2.5 euros, inserted 0 cents, 9 bottles left INPUT: machine.insertMoney(50) INPUT: machine.insertMoney(300) INPUT: machine.sellBottle() OUTPUT: res2: Int = 100 INPUT: machine OUTPUT: res3: o1.soda.VendingMachine = earned 5.0 euros, inserted 0 cents, 8 bottles left
As the example illustrates, a vending machine object has a mutable state: it keeps track of how much money the user has inserted, for instance. The machine also tracks the number of bottles it contains, the current (modifiable) price per bottle, and the money it has "earned" by selling bottles.
- Alphabetic
- By Inheritance
- VendingMachine
- AnyRef
- Any
- Hide All
- Show All
- Public
- Protected
Instance Constructors
- new VendingMachine(bottlePrice: Int, bottleCount: Int)
- bottlePrice
the price of a single bottle
- bottleCount
the initial number of bottles in the machine
Value Members
- def addBottles(newBottles: Int): Unit
(A maintenance action:) Adds a number of bottles to the machine.
(A maintenance action:) Adds a number of bottles to the machine. The virtual vending machine has no upper limit for bottles.
- newBottles
the number of bottles to be added (a positive integer)
- var bottlePrice: Int
- def emptyCashbox(): Int
(A maintenance action:) Removes all the earned cash from the machine.
(A maintenance action:) Removes all the earned cash from the machine.
- returns
the amount of money previously earned by the machine through sales
- def enoughMoneyInserted: Boolean
Determines whether enough money has been inserted to purchase a bottle.
- def insertMoney(amount: Int): Unit
(A customer action:) Adds some money towards a forthcoming purchase.
- def isSoldOut: Boolean
Determines whether the machine is out of bottles.
- def sellBottle(): Int
(A customer action:) Sells a bottle of virtual soda.
(A customer action:) Sells a bottle of virtual soda. This can only be done, however, if enough money has been inserted and there are bottles left in the machine. If the sale was successful, the method adds the earnings in the machine's cashbox, removes a single bottle, and sets up for the next transaction by resetting the amount of inserted cash to zero.
- returns
the amount of money (0 or more) given to the buyer as change, or a negative value to signal an unsuccessful purchase
- def toString: String
Produces a textual description of the vending machine's current state.
Produces a textual description of the vending machine's current state.
- Definition Classes
- VendingMachine → AnyRef → Any