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OOP exercises #1

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62 changes: 49 additions & 13 deletions src/main/java/com/amigoscode/_3_oop/_1_encapsulation/BankAccount.java
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Original file line number Diff line number Diff line change
Expand Up @@ -18,25 +18,43 @@ public class BankAccount {
// - accountNumber (String)
// - balance (double)
// - ownerName (String)
private String accountNumber;
private double balance;
private String ownerName;


// TODO: 2 - Create a constructor that takes accountNumber, ownerName,
// and an initialBalance. Validate that initialBalance >= 0,
// throwing IllegalArgumentException if not. Assign all fields.

public BankAccount(String accountNumber, String ownerName, double initialBalance){
if(initialBalance <0) throw new IllegalArgumentException("Balance should be greater or equal to 0!");
this.accountNumber=accountNumber;
this.ownerName = ownerName;
this.balance = initialBalance;
}


// TODO: 3 - Create a getter method for balance (getBalance).
// Do NOT create a setter for balance — it should only change
// through deposit() and withdraw().

public double getBalance(){
return this.balance;
}

// TODO: 4 - Create a deposit(double amount) method.
// - If amount <= 0, throw IllegalArgumentException with message
// "Deposit amount must be positive"
// - Add amount to balance
// - Call the private logTransaction() helper with a descriptive message
// - Return the new balance
public double deposit(double amount){
if(amount<=0) throw new IllegalArgumentException("Deposit amount must be positive");
this.balance += amount;
logTransaction("$%s was added successfully to account: %s".formatted(amount, accountNumber));
return this.balance;

}

// TODO: 5 - Create a withdraw(double amount) method.
// - If amount <= 0, throw IllegalArgumentException with message
Expand All @@ -46,32 +64,50 @@ public class BankAccount {
// - Subtract amount from balance
// - Call the private logTransaction() helper with a descriptive message
// - Return the new balance
public double withdraw(double amount){
if(amount<=0) throw new IllegalArgumentException("Withdrawal amount must be positive");
if(amount > balance) throw new IllegalStateException("Insufficient funds");
this.balance -= amount;
logTransaction("$%s was removed successfully to account: %s".formatted(amount, accountNumber));

return this.balance;
}

// TODO: 6 - Override toString() to return a string in the format:
// "BankAccount{accountNumber='XXX', ownerName='XXX', balance=XXX}"


@Override
public String toString() {
return "BankAccount{" +
"accountNumber='" + accountNumber + '\'' +
", balance=" + balance +
", ownerName='" + ownerName + '\'' +
'}';
}

// TODO: 7 - Create a private helper method logTransaction(String message)
// that prints the message to the console prefixed with
// "[Transaction Log] ". This method should NOT be accessible
// from outside the class.

private void logTransaction(String message){
System.out.println("[Transaction Log]: %s".formatted(message));
}

public static void main(String[] args) {
// Uncomment and test after completing the TODOs:
// BankAccount account = new BankAccount("ACC-001", "Alice", 1000.0);
// System.out.println(account);
// System.out.println("Balance: " + account.getBalance());
//
// account.deposit(500.0);
// System.out.println("After deposit: " + account.getBalance());
//
// account.withdraw(200.0);
// System.out.println("After withdrawal: " + account.getBalance());
BankAccount account = new BankAccount("ACC-001", "Alice", 1000.0);
System.out.println(account);
System.out.println("Balance: " + account.getBalance());
//
account.deposit(500.0);
System.out.println("After deposit: " + account.getBalance());

account.withdraw(200.0);
System.out.println("After withdrawal: " + account.getBalance());

// // These should throw exceptions:
// // account.deposit(-100);
// // account.withdraw(999999);
//account.deposit(-100);
//account.withdraw(999999);
}
}
60 changes: 46 additions & 14 deletions src/main/java/com/amigoscode/_3_oop/_1_encapsulation/ImmutablePerson.java
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Expand Up @@ -19,45 +19,77 @@ public final class ImmutablePerson {
// - name (String)
// - age (int)
// - email (String)
private final String name;
private final int age;
private final String email;


// TODO: 2 - Create a constructor that takes name, age, and email
// and assigns them to the fields. Since the fields are final,
// they can only be set here.

public ImmutablePerson(String name, int age, String email){
this.name = name;
this.age = age;
this.email = email;
}

// TODO: 3 - Create getter methods for all three fields:
// getName(), getAge(), getEmail().
// Do NOT create any setter methods — this class is immutable.
public String getName(){
return name;
}

public int getAge(){
return age;
}

public String getEmail() {
return email;
}

// TODO: 4 - Create a withName(String newName) method that returns
// a NEW ImmutablePerson with the changed name but the same
// age and email. The original object must remain unchanged.
public ImmutablePerson withName(String newName){
return new ImmutablePerson(newName, age, email);
}



// TODO: 5 - Create a withAge(int newAge) method that returns
// a NEW ImmutablePerson with the changed age but the same
// name and email. The original object must remain unchanged.

public ImmutablePerson withAge(int newAge){
return new ImmutablePerson(name, newAge, email);
}

// TODO: 6 - Override toString() to return a string in the format:
// "ImmutablePerson{name='XXX', age=XXX, email='XXX'}"


@Override
public String toString() {
return "ImmutablePerson{" +
"name='" + name + '\'' +
", age=" + age +
", email='" + email + '\'' +
'}';
}

public static void main(String[] args) {
// Uncomment and test after completing the TODOs:
// ImmutablePerson person = new ImmutablePerson("Alice", 30, "alice@example.com");
// System.out.println(person);
//
// // withName returns a NEW object — original is unchanged
// ImmutablePerson renamed = person.withName("Bob");
// System.out.println("Original: " + person);
// System.out.println("Renamed: " + renamed);
//
// // withAge returns a NEW object — original is unchanged
// ImmutablePerson aged = person.withAge(31);
// System.out.println("Original: " + person);
// System.out.println("Aged: " + aged);
ImmutablePerson person = new ImmutablePerson("Alice", 30, "alice@example.com");
System.out.println(person);

// withName returns a NEW object — original is unchanged
ImmutablePerson renamed = person.withName("Bob");
System.out.println("Original: " + person);
System.out.println("Renamed: " + renamed);

// withAge returns a NEW object — original is unchanged
ImmutablePerson aged = person.withAge(31);
System.out.println("Original: " + person);
System.out.println("Aged: " + aged);
}
}
31 changes: 24 additions & 7 deletions src/main/java/com/amigoscode/_3_oop/_2_inheritance/Animal.java
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Expand Up @@ -17,31 +17,48 @@ public class Animal {
// TODO: 1 - Declare two protected fields:
// - name (String)
// - age (int)

protected String name;
protected int age;

// TODO: 2 - Create a constructor that takes name and age
// and assigns them to the fields.

public Animal(String name, int age){
this.name = name;
this.age = age;
}

// TODO: 3 - Create a makeSound() method that prints:
// "Some generic animal sound"
// Subclasses will override this with their specific sound.

public void makeSound(){
System.out.println("Some generic animal sound");
}

// TODO: 4 - Create an eat(String food) method that prints:
// "<name> is eating <food>"
// For example: "Buddy is eating kibble"
public void eat(String food){
String msg = "%s is eating %s".formatted(this.name, food);
System.out.println(msg);
}


// TODO: 5 - Override toString() to return:
// "Animal{name='XXX', age=XXX}"

@Override
public String toString() {
return "Animal{" +
"name='" + name + '\'' +
", age=" + age +
'}';
}

public static void main(String[] args) {
// Uncomment and test after completing the TODOs:
// Animal animal = new Animal("Generic", 5);
// System.out.println(animal);
// animal.makeSound();
// animal.eat("food");
Animal animal = new Animal("Generic", 5);
System.out.println(animal);
animal.makeSound();
animal.eat("food");
}
}
42 changes: 30 additions & 12 deletions src/main/java/com/amigoscode/_3_oop/_2_inheritance/Dog.java
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Expand Up @@ -16,43 +16,61 @@

// TODO: 1 - Make this class extend Animal.
// Change the class declaration so Dog inherits from Animal.
public class Dog {
public class Dog extends Animal{

// TODO: 2 - Add a private field:
// - breed (String)
private String breed;


// TODO: 3 - Create a constructor that takes name, age, and breed.
// Call super(name, age) to initialize the parent fields,
// then set the breed field.

public Dog(String name, int age, String breed){
super(name, age);
this.breed = breed;
}

// TODO: 4 - Override the makeSound() method to print:
// "<name> says: Woof! Woof!"
// Use the @Override annotation. You can access `name` because
// it is a protected field in Animal.

@Override
public void makeSound(){
String sound = "%s says: Woof! Woof!".formatted(name);
System.out.println(sound);
}

// TODO: 5 - Add a fetch(String item) method specific to Dog.
// This method should print:
// "<name> fetches the <item>!"
// This method does not exist in Animal — it is unique to Dog.

public void fetch(String item){
String msg = "%s fetches the %s".formatted(name, item);
System.out.println(msg);
}

// TODO: 6 - Override toString() to return:
// "Dog{name='XXX', age=XXX, breed='XXX'}"

@Override
public String toString() {
return "Dog{" +
"name='" + name + '\'' +
", age=" + age +
", breed='" + breed + '\'' +
'}';
}

public static void main(String[] args) {
// Uncomment and test after completing the TODOs:
// Dog dog = new Dog("Buddy", 3, "Golden Retriever");
// System.out.println(dog);
// dog.makeSound();
// dog.eat("kibble"); // inherited from Animal
// dog.fetch("tennis ball"); // specific to Dog
Dog dog = new Dog("Buddy", 3, "Golden Retriever");
System.out.println(dog);
dog.makeSound();
dog.eat("kibble"); // inherited from Animal
dog.fetch("tennis ball"); // specific to Dog
//
// // Polymorphism: a Dog IS-AN Animal
// Animal animal = new Dog("Rex", 5, "German Shepherd");
// animal.makeSound(); // calls Dog's overridden version
Animal animal = new Dog("Rex", 5, "German Shepherd");
animal.makeSound(); // calls Dog's overridden version
}
}
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