Vending Machine

1
Vending Machine
2
What does a vending machine do?

• Keeps and dispenses cans of soda
• Sodas have a type and a cost
• Machine totals up the money

3
The Vending Machine Class

• Framework no main
• public class VendingMachineClass
• private int numCans
• private double sodaCost
• private String sodaType
• private double totalMoney 0

4
The Constructor

• public class VendingMachineClass
• private int numCans
• private double sodaCost
• private String sodaType
• private double totalMoney 0
• public VendingMachineClass(String inType,double
  inCost,int inNumber)
• sodaCost inCost
• sodaType inType
• numCans inNumber
• totalMoney 0

5

• public VendingMachineClass(String inType,double
  inCost,int inNumber)
• sodaCost inCost
• sodaType inType
• numCans inNumber
• totalMoney 0
• System.out.println()
• System.out.println("Soda Machine Created with
  ")
• System.out.println("Type "sodaType)
• System.out.println("Cost " sodaCost)
• System.out.println("Number of Cans " numCans)
• System.out.println("Total at start "
  totalMoney)

6

• public VendingMachineClass(String inType,double
  inCost,int inNumber)
• sodaCost inCost
• sodaType inType
• numCans inNumber
• totalMoney 0
• if(inType.equals("Pepsi") true) // new String
  method!
• System.out.println("Sorry, no Pepsi, just
  Coke")
• inType "Coke"
• System.out.println()
• System.out.println("Soda Machine Created with
  ")
• System.out.println("Type "sodaType)
• System.out.println("Cost " sodaCost)
• System.out.println("Number of Cans " numCans)
• System.out.println("Total at start "
  totalMoney)

7
Accessors - one for each private variable

• public int getNumCans()
• return(numCans)
• public String getSodaType(
• return(sodaType)
• public double getCost()
• return(sodaCost)

8
Mutator - for each variable that is settable

• public void addCans(int howMany )
• System.out.println(Adding " howMany " cans of
  " sodaType)
• numCans numCans howMany

9

• public void buyCans( int howMany )
• numCans numCans - howMany
• totalMoney totalMoney (howMany sodaCost)
• // end buy cans method

10

• public void buyCans( int howMany )
• // adjust for request larger than available
• if (howMany gt numCans)
• howMany numCans
• numCans numCans - howMany
• totalMoney totalMoney (howMany sodaCost)
• // end buy cans method

11

• public void buyCans( int howMany )
• System.out.println("-gt in method BuyCans")
• System.out.println(Attempting to buy howMany
  " cans of " sodaType)
• if (howMany gt numCans)
• System.out.println("Sorry, there's only "
  numCans " left")
• System.out.println("Buying " numCans)
• howMany numCans
• numCans numCans - howMany
• totalMoney totalMoney (howMany sodaCost)
• System.out.println("TotalCash now " totalMoney
  " in machine " sodaType)
• System.out.println("-gt leaving method buyCans")
  
• // end buy cans method

12
Main

• different class
• must be present
• uses VendingMachineClass (instantiates)

13

• public class VendingMachineUser
• public static void main(String args)
• VendingMachineClass machine1 new
  VendingMachineClass("Pepsi", .75, 100)
• // end main
• //end class

14

• public class VendingMachineUser
• public static void main(String args)
• int howManyLeft
• String whatType
• VendingMachineClass machine1 new
  VendingMachineClass("Pepsi", .75, 100)
• // buy some
• machine1.buyCans(60)
• // display what's left
• howManyLeft machine1.getNumCans()
• whatType machine1.getSodaType()
• System.out.println("Results....")
• System.out.println(howManyLeft " cans of "
  whatType " left ")
• System.out.println()

15

• public class VendingMachineUser
• public static void main(String args)
• int howManyLeft
• String whatType
• VendingMachineClass machine1 new
  VendingMachineClass("Pepsi", .75, 100)
• VendingMachineClass machine2 new
  VendingMachineClass(Orange", .65, 120)
• // buy some
• machine1.buyCans(60)
• machine2.buyCans(40)
• // display what's left in machine 1
• howManyLeft machine1.getNumCans()
• whatType machine1.getSodaType()
• System.out.println(howManyLeft " cans of "
  whatType " left in machine 1")