• What is polymorphism?
• Compile-time vs runtime polymorphism
• Upcasting and downcasting
• Benefits of polymorphism

• Polymorphism: Many forms
• Upcasting: Parent reference to child object
• Downcasting: Child reference from parent object

1. PolymorphismDemo.java - Example of basic polymorphism
2. PolymorphismMethodDemo.java - Demonstrates polymorphism in method parameters and return types
3. UpcastingDowncastingDemo.java - Shows upcasting and downcasting with instanceof checks

1. Compile: javac PolymorphismDemo.java PolymorphismMethodDemo.java UpcastingDowncastingDemo.java
2. Run: java PolymorphismDemo (or the other classes)

1. Demonstrate upcasting and downcasting
2. Use polymorphism in a method

Next Day: Day 19 - Abstract Classes