feat: Demonstrate access modifiers with inheritance in Animal–Dog example

WHAT the code does:
- Defines Animal class:
  - Private field name, accessible only inside Animal.
  - Protected field sound, accessible within same package and subclasses.
  - Constructor initializes name and sound (bug: parameter `Sound` capitalized but not used; should assign correctly).
  - makeSound(): prints name and sound.
  - changeSound(): protected method to change sound.
- Defines Dog class extending Animal:
  - Constructor calls super(name, "Bark").
  - wagTail(): prints class name + wagging message.
  - getName(): returns class’s simple name via reflection.
  - setDogSound(): wraps the protected changeSound() so external code can safely modify sound.
- Defines Test class:
  - Creates Dog instance.
  - Calls makeSound() → prints initial "Bark".
  - Attempts dog.changeSound("Woof"); (illegal access since Test isn’t subclass of Animal, even though in same package this would compile — but intent is to show protection).
  - Calls dog.setDogSound("Woof"); → uses subclass’s public wrapper.
  - Calls makeSound() again → prints updated sound.
  - Calls wagTail() → accessible since it’s public.

WHY this matters:
- Demonstrates **access modifiers** in Java:
  - private: visible only in the class itself.
  - protected: visible in same package and subclasses.
  - public: visible everywhere.
- Shows **inheritance and encapsulation** working together:
  - Subclass Dog can use protected methods of Animal.
  - External code (Test) cannot directly access protected members unless in same package context.
  - Public wrappers like setDogSound() provide controlled access.

HOW it works:
1. Dog created with name "Bob" and sound "Bark".
2. dog.makeSound() → "null Make a sound: Bark" (bug: Animal constructor didn’t set name correctly).
3. dog.setDogSound("Woof") → updates sound via protected method.
4. dog.makeSound() → prints with new sound.
5. dog.wagTail() → prints "Dogis wagging its tail." (no space because getName() returns "Dog").

Tips and gotchas:
- Bug: Animal constructor’s parameter `Sound` should be lowercase to assign correctly: `this.sound = Sound;`.
- Better naming: `Animal(String name, String sound)` for consistency.
- Avoid naming collision between field name and method name (`getName()` here returns class name, not the private field).
- To expose private `name`, add a getter in Animal.
- Protected access: since Test is in the same package ZOO, it actually *can* call dog.changeSound(), but outside the package it would fail unless Test is subclass.

Use-cases / analogies:
- Encapsulation like this ensures only subclasses or controlled wrappers can change sensitive fields.
- Like a zoo manager (Animal) allowing only zookeepers (Dog subclass) to change animal behaviors, not visitors (Test).

Short key: java access-modifiers inheritance protected-private public encapsulation.

Signed-off-by: https://github.com/Someshdiwan <[email protected]>

Author: Someshdiwan

Section17Packages/src/ZOO/Animal.java

@@ -13,8 +13,7 @@ public void makeSound() {
         System.out.println(name + " Make a sound: " + sound);
     }
 
-    protected void changeSound(String newSound)
-    {
+    protected void changeSound(String newSound) {
         this.sound = newSound;
     }
-}
+}