The Simplest, most Powerful Class Architecture

1
The Simplest, most Powerful Class Architecture
2
Our Mortgage Company

• public class MortgageCompany// PROPERTIES of a
  mortgage lenderdouble CashOnHand 0double
  LoanedMoney 0double InterestProfit
  0double Debt 0
• int HealthyMortgages 0int RiskyMortgages
  0int FailedMortgages 0// calculated
  valuesint NumberOfMortgages 0double
  AverageMortgage 0double ForeclosedProperties
  0double PresentHealth 0double
  PredictedHealth 0

3
Behaviors

• // this behavior calculates the current and
  predicted health of a mortgage
• // company
• public void CalculateHealth( )
• NumberOfMortgages HealthyMortgages
  RiskyMortgages FailedMortgages
• AverageMortgage LoanedMoney /
  (double)NumberOfMortgages
• ForeclosedProperties (double)FailedMortgages
  AverageMortgage
• PresentHealth CashOnHand LoanedMoney
  InterestProfit
• ForeclosedProperties Debt
• PredictedHealth PresentHealth -
  ((double)RiskyMortgages AverageMortgage)
• // end method

4

• // this behavior adjusts the number and
• // amount of each mortgage type
• public void AdjustMortgages( int Healthy, int
  Failed, int Risky )
• HealthyMortgages Healthy
• FailedMortgages Failed
• RiskyMortgages Risky
• // end method

5
One more define INITIAL behavior

• // needed for construction
• // a method with the SAME NAME as the class
• // accepts 4 important values
• public MortgageCompany( double InitialCash,
  double InitialLoans,
• 
  double InitialProfit, double
  InitialDebt )
• CashOnHand InitialCash
• LoanedMoney InitialLoans
• InterestProfit InitialProfit
• Debt InitialDebt

6
a class CONSTRUCTOR

• lets you set the initial personality of a class,
  when its copied into an object in main.
• has the same name as the class
• defined as
• public className( any parameters )

7
Now, how do we USE a mortgage company model
(class), in main

• // create a mortgage company object
• // use constructor
• MortgageCompany mortgageA
• new MortgageCompany( 10000.00, 2500000.00,
  10000.00, 200000.00)

8
in main, (remember, in another file)

• // go get stuff from the user
• userInput JOptionPane.showInputDialog("Enter
  Healthy Mortgages ")
• x Integer.parseInt( userInput )
• userInput JOptionPane.showInputDialog("Enter
  Failed Mortgages ")
• y Integer.parseInt( userInput )
• userInput JOptionPane.showInputDialog("Enter
  Risky Mortgages ")
• z Integer.parseInt( userInput )
• // set all the numbers
• mortgageA.AdjustMortgages( x, y, z )

9

• // see the result
• mortgageA.CalculateHealth()
• System.out.println( "Present Health of Mortgage
  A " mortgageA.PresentHealth )
• System.exit(0)

10
A single file

• pretty much limited to what you can write, in one
  file.
• Does not use any other classes. That's limiting.

11
Two Files

• Move start point to another file.
• Separation of function always a good thing.
• Keep all files in same folder.

12
Three Files (or more)

• Your program can use other class files as
  properties.

13
How can your program use other classes?

• Instantiate them, as long as the other class
  files are nearby.
• Import them