1.3 Zoo Learning Activity

Zoo Instruction

1.Overview

A Methods

Zoo 1.3 shifts from objects that mainly store state to objects that also perform behavior. You will add parameterless void methods to the existing zoo model, connect those methods to UI actions, and trace execution as methods call other methods.

Fields describe an object's state. Methods describe what an object can do.

B Getting Started

C Make a copy of the Zoo 1.2 [LastName] folder

D Rename the copied folder to Zoo 1.3 [LastName]

E Rename Zoo 1.2 [LastName].sln to Zoo 1.3 [LastName].sln

F Open the copied Zoo 1.3 solution in Visual Studio

G Build the solution before making changes

Keep your Zoo 1.2 checkpoint unchanged. If a later change causes a problem, the previous working checkpoint gives you a known-good source to compare against.

H Starting Point — End of Zoo 1.2

Zoo 1.3 begins with the two-zoo object model already established. The existing project includes the current Zoo, Animal, Employee, Restroom, Booth, BirthingRoom, and VendingMachine classes, plus the Como and San Diego object graphs.

Zoo 1.2 starting class structure for Zoo 1.3. MainWindow references ComoZoo and SanDiegoZoo. Each Zoo references its existing featured animal, restrooms, ticket booth, birthing room, and vending machine. No Zoo 1.3 additions are marked. — Starting structure: authoritative end-of-Zoo-1.2 context.

This checkpoint adds behavior without introducing later-course concepts. The custom methods added here remain parameterless and return void.

I Acceptance Criteria

Each zoo guest is connected to a Wallet.
Wallet.RemoveMoney() subtracts the fixed $$2.00 feeding amount.
VendingMachine.AddMoney() adds $$2.00.
VendingMachine.SellFood() calls AddMoney() and subtracts 1.0 from FoodStock.
Animal.Eat() changes the animal's weight using the current endpoint calculation.
The Como and San Diego feed actions call RemoveMoney() → SellFood() → Eat() in that order.
VendingMachine.AddFoodBag() increases stock by the current BagSize.
Animal.MakePregnant() changes pregnancy state and Animal.Move() represents movement behavior.
CreateComoZoo() and CreateSanDiegoZoo() organize the two creation flows.
The debugger is used to trace method calls with Step Over, Step Into, Step Out, Continue, and the Call Stack.

Complete a guest feeding transaction

User Story: As a zoo guest, I want to purchase food and feed the zoo's featured animal so that one action updates my wallet, the vending machine, and the animal consistently.

Acceptance Criteria

Each zoo visitor has a separate Wallet containing the current starting balance.
One feeding purchase removes 2.0m from the guest wallet.
One vending-machine sale adds 2.0m to MoneyBalance and removes 1.0 from FoodStock.
The featured animal updates its own weight through Eat() using the current Zoo 1.3 calculation.
The Como and San Diego feed actions call the same object-owned behaviors in the order RemoveMoney() → SellFood() → Eat().
The UI coordinates the transaction without duplicating the state-change calculations owned by Wallet, VendingMachine, and Animal.
You can trace the transaction with Step Into, Step Out, Continue, and the Call Stack.

2.Give each zoo guest a wallet

A Add Wallet

Add Wallet.cs to the existing Business Classes folder. Keep the current project namespace, XML documentation style, and StyleCop suppression pattern.

public decimal MoneyBalance;

B Add Wallet.cs to the Business Classes folder

C Add the documented MoneyBalance : decimal field

D Do not add properties or constructors

E Add Guest

public double PortionSize;
public int Age;
public string Name;
public Wallet Wallet;

public void Eat()
{
    // No state change is needed for this example.
}

F Add Guest.cs to the Business Classes folder

G Add PortionSize, Age, Name, and the Wallet reference

H Add the current parameterless Eat() method

I Connect the visitor to Zoo

public Guest Visitor;

Progressive Zoo 1.3 class diagram. Green squares mark the new Guest and Wallet classes, their current fields and Guest Eat method, Zoo Visitor relationship, and Guest Wallet relationship. — Add Guest and Wallet and connect them to Zoo.

J Add the documented Visitor : Guest relationship to Zoo

K Create the current visitors and wallets

Current visitors and wallets
Value	Como Zoo	San Diego Zoo
Guest	Darla	Dave
Age	11	13
PortionSize	1.0	1.0
Wallet balance	5.25m	3.75m

L Create Darla and her Wallet in the Como Zoo setup flow

M Create Dave and his Wallet in the San Diego Zoo setup flow

N Check Your Work

1 Build

2 Confirm ComoZoo.Visitor.Name = "Darla" and ComoZoo.Visitor.Wallet.MoneyBalance = 5.25m

3 Confirm SanDiegoZoo.Visitor.Name = "Dave" and SanDiegoZoo.Visitor.Wallet.MoneyBalance = 3.75m

4 Confirm the two guests reference separate Wallet objects

3.Pay for one feeding transaction

A Add RemoveMoney()

Progressive Wallet class diagram. A green square marks the new RemoveMoney method; MoneyBalance is existing context from the current task. — Add the focused RemoveMoney behavior to Wallet.

public void RemoveMoney()
{
    this.MoneyBalance -= 2.0m;
}

The m suffix makes 2.0m a decimal. If the balance starts at 5.25m, one call produces 3.25m.

B Add the documented parameterless void RemoveMoney() method to Wallet

C Keep the fixed 2.0m subtraction inside Wallet

D Check Your Work

1 Build

2 Confirm RemoveMoney() belongs to Wallet

3 Confirm it subtracts exactly 2.0m and does not return a value

4.Record money received by the vending machine

A Add AddMoney()

Progressive VendingMachine class diagram. A green square marks the new AddMoney method; existing vending-machine fields are unmarked. — Add AddMoney to VendingMachine.

public void AddMoney()
{
    this.MoneyBalance += 2.0m;
}

B Add AddMoney() to VendingMachine

C Keep the fixed 2.0m addition inside the vending machine

D Check Your Work

1 Build

2 Confirm the method changes the current vending machine's MoneyBalance

3 Confirm it has no custom parameters and returns void

5.Sell one pound of animal food

A Add SellFood()

Progressive VendingMachine class diagram. A green square marks the new SellFood method; AddMoney and the current state fields remain unmarked context. — SellFood becomes a second focused vending-machine behavior.

Sequence diagram for one vending-machine sale. A green square marks the SellFood call. SellFood calls AddMoney on the same vending-machine object, then the machine reduces FoodStock. — SellFood calls another method on the same object before updating food stock.

public void SellFood()
{
    this.AddMoney();
    this.FoodStock -= 1.0;
}

this.AddMoney() calls another method on the same VendingMachine object. When that call returns, execution continues with the FoodStock subtraction.

B Add SellFood() to VendingMachine

C Call AddMoney() before reducing FoodStock

D Subtract exactly 1.0 from the current food stock

E Check Your Work

1 Build

2 Confirm SellFood() calls AddMoney()

3 Confirm one sale adds 2.0m to money and removes 1.0 pound of food

6.Let the featured animal eat

A Add the current weight-gain percentage

public double EatWeightGainPercentage = 0.8;

B Add Eat()

Progressive Animal class diagram. Green squares mark the new EatWeightGainPercentage field and Eat method; existing Animal state remains unmarked context. — Animal gains its first current feeding behavior.

public void Eat()
{
    this.Weight = this.Weight + this.Weight * this.EatWeightGainPercentage;
}

For Dolly: 35.3 + 35.3 × × 0.8 = 63.54.

For Patti: 3.27 + 3.27 × × 0.8 = 5.886.

C Add or confirm EatWeightGainPercentage = 0.8 in Animal

D Add the parameterless void Eat() method

E Keep the weight calculation inside Animal

F Check Your Work

1 Build

2 Confirm Dolly changes from 35.3 to 63.54 after one call

3 Confirm Patti changes from 3.27 to 5.886 after one call

7.Connect the Como Zoo feeding action

A Confirm the button

XAML

<Button x:Name="darlaFeedDingoButton" Content="Darla, feed dingo" Click="darlaFeedDingoButton_Click"/>

B Complete the event handler

public void darlaFeedDingoButton_Click(object sender, RoutedEventArgs e)
{
    this.ComoZoo.Visitor.Wallet.RemoveMoney();
    this.ComoZoo.AnimalSnackMachine.SellFood();
    this.ComoZoo.FeaturedAnimal.Eat();
}

Sequence diagram for the Como feeding transaction. Green squares mark the UI-requested calls RemoveMoney, SellFood, and Eat. SellFood makes the nested AddMoney call on the same vending-machine object. — Como feed flow: wallet payment → vending-machine sale → animal eating.

C Call RemoveMoney() on Darla's wallet

D Call SellFood() on the Como vending machine

E Call Eat() on Dolly

F Keep the calls in that order

If FoodStock is 0, one sale produces -1.0. Do not add an if statement in Zoo 1.3; decision logic belongs to a later checkpoint.

G Check Your Work

1 From a fresh Como Zoo without refilling, confirm Darla changes 5.25 → → 3.25

2 Confirm vending money changes 0 → → 2.00

3 Confirm food stock changes 0 → → -1.0

4 Confirm Dolly changes 35.3 → → 63.54

8.Connect the San Diego Zoo feeding action

A Confirm the button

XAML

<Button x:Name="daveFeedPlatypusButton" Content="Dave, feed platypus" Click="daveFeedPlatypusButton_Click"/>

B Complete the event handler

public void daveFeedPlatypusButton_Click(object sender, RoutedEventArgs e)
{
    this.SanDiegoZoo.Visitor.Wallet.RemoveMoney();
    this.SanDiegoZoo.AnimalSnackMachine.SellFood();
    this.SanDiegoZoo.FeaturedAnimal.Eat();
}

C Call the three existing methods through the San Diego object graph

D Keep the transaction order the same as Como Zoo

E Check Your Work

1 From a fresh San Diego Zoo without refilling, confirm Dave changes 3.75 → → 1.75

2 Confirm vending money changes 0 → → 2.00

3 Confirm food stock changes 0 → → -1.0

4 Confirm Patti changes 3.27 → → 5.886

9.Trace the feeding transaction

A Trace the wallet call

Method-call trace map for the Como feeding transaction. MainWindow calls Wallet.RemoveMoney, VendingMachine.SellFood, and Animal.Eat; SellFood calls AddMoney on the same vending machine. — Use this sequence as the map for the debugger trace.

Set a breakpoint on:

this.ComoZoo.Visitor.Wallet.RemoveMoney();

B Run the application and create a fresh Como Zoo

C Click Darla, feed dingo and stop at the breakpoint

D Step Into Wallet.RemoveMoney()

E Inspect MoneyBalance before and after the subtraction

F Step Out to return to the event handler

G Trace the nested vending-machine call

H Step Into VendingMachine.SellFood()

I Step Into this.AddMoney() from inside SellFood()

J Open the Call Stack while paused in AddMoney()

VendingMachine.AddMoney()
VendingMachine.SellFood()
MainWindow.darlaFeedDingoButton_Click(...)

K Step through the money addition

L Step Out to SellFood() and execute the food-stock subtraction

M Trace the animal call

N Return to the event handler and Step Into Animal.Eat()

O Inspect Dolly's Weight and EatWeightGainPercentage before the calculation

P Execute the calculation and confirm Weight = 63.54

Q Press F5 (Continue) when the trace is complete

R Check Your Work

You can explain how the event handler calls three different object behaviors.
You can identify the nested SellFood() → → AddMoney() path in the Call Stack.
You can use Step Out to return to a caller.

Keep animal-food vending machines stocked

10.Add a food bag to a vending machine

A Add AddFoodBag()

Progressive VendingMachine class diagram. A green square marks the new AddFoodBag method; AddMoney and SellFood are existing Zoo 1.3 context. — Add the vending-machine refill behavior.

public void AddFoodBag()
{
    this.FoodStock += this.BagSize;
}

B Add AddFoodBag() to VendingMachine

C Use the current machine's BagSize; do not duplicate the value inside the UI handler

D Check Your Work

Build.
With BagSize = 65 and FoodStock = 0, one call produces 65.
A second call produces 130.

11.Refill the Como Zoo vending machine

A Confirm the button and handler

Sequence diagram for the refill action. A green square marks MainWindow calling AddFoodBag on the current VendingMachine, which updates FoodStock from its current value using BagSize. — The UI requests the refill; the vending machine owns the stock calculation.

XAML

<Button x:Name="floraFillVendingMachineButton" Content="Flora, fill vending machine" Click="floraFillVendingMachineButton_Click"/>

public void floraFillVendingMachineButton_Click(object sender, RoutedEventArgs e)
{
    this.ComoZoo.AnimalSnackMachine.AddFoodBag();
}

B Call AddFoodBag() on ComoZoo.AnimalSnackMachine

C Check Your Work

1 Create a fresh Como Zoo

2 Confirm FoodStock = 0, click the refill button once, and confirm FoodStock = 65

12.Refill the San Diego Zoo vending machine

A Confirm the button and handler

XAML

<Button x:Name="bettyFillVendingMachineButton" Content="Betty, fill vending machine" Click="bettyFillVendingMachineButton_Click"/>

public void bettyFillVendingMachineButton_Click(object sender, RoutedEventArgs e)
{
    this.SanDiegoZoo.AnimalSnackMachine.AddFoodBag();
}

B Call AddFoodBag() on SanDiegoZoo.AnimalSnackMachine

C Check Your Work

1 Create a fresh San Diego Zoo

2 Confirm FoodStock = 0, click the refill button once, and confirm FoodStock = 65

13.Verify repeated refills

A Refill more than once

B Create a fresh Como Zoo and confirm FoodStock = 0

C Refill once and confirm FoodStock = 65

D Refill again and confirm FoodStock = 130

E Combine refill and feed

F Create a fresh Como Zoo

G Refill once

H Feed Dolly once

I Check Your Work

Darla wallet = 3.25.
Como vending MoneyBalance = 2.00.
Como vending FoodStock = 64.0.
Dolly Weight = 63.54.

Let zoo objects perform focused behaviors

14.Change pregnancy state through behavior

A Add MakePregnant()

Progressive Animal class diagram. A green square marks the new MakePregnant method; current weight and feeding behavior remain unmarked context. — Add pregnancy-state behavior to Animal.

public void MakePregnant()
{
    this.IsPregnant = true;
}

B Add the documented parameterless void MakePregnant() method to Animal

C Check Your Work

1 Build

2 Confirm the method changes the current animal's IsPregnant field to true

15.Represent animal movement as behavior

A Add Move()

Progressive Animal class diagram. A green square marks the new Move method; Eat and MakePregnant are existing Zoo 1.3 behavior. — Add movement as an Animal-owned behavior.

public void Move()
{
}

B Add Move() to Animal

C Leave the body empty for Zoo 1.3

D Check Your Work

1 Build

2 Confirm the method is parameterless and returns void

16.Use MakePregnant() when creating the featured animals

A Call the behavior for Dolly

Sequence diagram showing MainWindow's zoo-creation method calling MakePregnant on the current featured Animal. A green square marks the CreateComoZoo call in this focused diagram. — The creation method requests the animal's pregnancy-state behavior.

this.ComoZoo.FeaturedAnimal.MakePregnant();

B Call the behavior for Patti

this.SanDiegoZoo.FeaturedAnimal.MakePregnant();

C Call MakePregnant() after Dolly is initialized

D Call MakePregnant() after Patti is initialized

E Do not directly assign IsPregnant = true from MainWindow for these actions

F Check Your Work

1 Create each zoo

2 Confirm both featured animals have IsPregnant = true

Organize zoo creation into focused application actions

User Story: As a user of the zoo application, I want each New Zoo button to trigger one clear creation action so that the complete zoo is assembled consistently without placing the full setup algorithm in the event handler.

Acceptance Criteria

CreateComoZoo() contains the established Como object-creation flow and preserves its current relationships and values.
CreateSanDiegoZoo() contains the established San Diego object-creation flow and preserves its current relationships and values.
The New Como Zoo event handler delegates creation to CreateComoZoo().
The New San Diego Zoo event handler delegates creation to CreateSanDiegoZoo().
Dolly and Patti still become pregnant through MakePregnant() inside their respective creation flows.
The resulting zoos match the current checkpoint state after creation.
You can trace the nested path from a button event into a creation method and then into Animal.MakePregnant().

17.Create the Como Zoo through a focused method

A Add the creation method

Progressive class diagram. Green squares mark the new MainWindow CreateComoZoo and CreateSanDiegoZoo methods. Existing Zoo and FeaturedAnimal relationships provide context. — Move the two large setup flows into focused MainWindow methods.

public void CreateComoZoo()

Move the existing Como creation statements into this method. Do not rewrite the entire object graph from memory; preserve the current working relationships and values.

Current Como Zoo state
Area	Current state
Zoo	Name = "Como Zoo", Capacity = 1000
Ticket booth	TicketPrice = 15.00m, attendant Sam, number 42
Visitor	Darla, age 11, wallet 5.25m, portion size 1.0
Vending machine	BagSize = 65.0, FoodCapacity = 250.0, FoodPricePerPound = 0.75m
Birthing room	InitialTemperature = 77.0, max 85.0, min 55.0, increase 0.5, current temperature = initial temperature
Doctor	Flora, number 98
Restrooms	Ladies: capacity 4, Female; Mens: capacity 4, Male
Featured animal	Dolly, Female, age 4, weight 35.3, happiness 0, type Dingo, pregnancy through MakePregnant()

B Create CreateComoZoo() in MainWindow

C Move the existing Como object-creation statements into the method

D Preserve the current relationships and values shown above

E Call MakePregnant() after Dolly is initialized

F Check Your Work

1 Build

2 Confirm Como InitialTemperature = 77.0

3 Confirm vending FoodStock and MoneyBalance begin at their default numeric value 0

4 Confirm Dolly is pregnant through MakePregnant()

18.Connect the New Como Zoo control

A Simplify the event handler

public void newComoZooButton_Click(object sender, RoutedEventArgs e)
{
    this.CreateComoZoo();
}

B Replace the detailed Como setup inside the event handler with the call to CreateComoZoo()

C Check Your Work

1 Build and run

2 Click New Como Zoo and confirm the complete zoo is still created

19.Create the San Diego Zoo through a focused method

A Add the creation method

public void CreateSanDiegoZoo()

Current San Diego Zoo state
Area	Current state
Zoo	Name = "San Diego Zoo", Capacity = 3000
Ticket booth	TicketPrice = 25.50m, attendant Betty, number 84
Visitor	Dave, age 13, wallet 3.75m, portion size 1.0
Vending machine	BagSize = 65.0, FoodCapacity = 250.0, FoodPricePerPound = 1.20m
Birthing room	InitialTemperature = 77.0, max 85.0, min 55.0, increase 0.5, current temperature = initial temperature
Doctor	Steve, number 24
Restrooms	Ladies: capacity 12, Female; Mens: capacity 12, Male
Featured animal	Patti, Female, age 5, weight 3.27, happiness 0, type Platypus, pregnancy through MakePregnant()

B Create CreateSanDiegoZoo() in MainWindow

C Move the existing San Diego object-creation statements into the method

D Preserve the current relationships and values shown above

E Call MakePregnant() after Patti is initialized

F Check Your Work

1 Build

2 Confirm San Diego InitialTemperature = 77.0

3 Confirm Patti is pregnant through MakePregnant()

20.Connect the New San Diego Zoo control

A Simplify the event handler

public void newSanDiegoZooButton_Click(object sender, RoutedEventArgs e)
{
    this.CreateSanDiegoZoo();
}

B Replace the detailed San Diego setup inside the event handler with the call to CreateSanDiegoZoo()

C Check Your Work

1 Build and run

2 Click New San Diego Zoo and confirm the complete zoo is still created

21.Trace a method called from another method

A Enter the creation method

Method-call trace map for zoo creation. The New Como Zoo event enters MainWindow.CreateComoZoo, which calls Animal.MakePregnant on the featured animal. — Use this sequence as the map for the zoo-creation debugger trace.

Set a breakpoint on:

this.CreateComoZoo();

B Run the application and click New Como Zoo

C Step Into CreateComoZoo()

D Continue until execution reaches this.ComoZoo.FeaturedAnimal.MakePregnant();

E Enter the animal method

F Step Into Animal.MakePregnant()

G Inspect IsPregnant before and after the assignment

H Open the Call Stack

Code

Animal.MakePregnant()
MainWindow.CreateComoZoo()
MainWindow.newComoZooButton_Click(...)

I Step Out to return to CreateComoZoo()

J Step Out again to return to the event handler

K Check Your Work

You can explain the three-level call path from the UI event to the animal method.
You can identify the current method and its callers in the Call Stack.

23.Checkpoint Summary

Final Zoo 1.3 class diagram. Green squares mark all new Zoo 1.3 structural items: Guest, Wallet, Zoo Visitor and Guest Wallet relationships; Wallet RemoveMoney; Animal EatWeightGainPercentage, Eat, MakePregnant, and Move; VendingMachine AddFoodBag, AddMoney, and SellFood; and MainWindow CreateComoZoo and CreateSanDiegoZoo. Existing Zoo 1.2 context is unmarked. There are no Changed or Removed structural items. — Final structural delta: New items only; Changed none; Removed none.

A Feeding transaction

Code

Wallet.RemoveMoney()
VendingMachine.SellFood()
    → VendingMachine.AddMoney()
Animal.Eat()

B Other current behaviors

Code

VendingMachine.AddFoodBag()
Animal.MakePregnant()
Animal.Move()
MainWindow.CreateComoZoo()
MainWindow.CreateSanDiegoZoo()

All custom methods introduced at this checkpoint remain parameterless void methods. Parameters, returned values, and decision logic are reserved for later checkpoints.