Module 23: Final Keyword

🔒 What is the final Keyword?

The final keyword in Java is used to restrict the user. It can be applied to variables, methods, and classes with different effects:

• Final Variable: Its value cannot be changed once assigned.
• Final Method: Cannot be overridden by subclasses.
• Final Class: Cannot be inherited.

📘 Examples

1. Final Variable

                    final int MAX = 100;
                    MAX = 200;  // Error: cannot assign a value to final variable
                    

2. Final Method

                    class Animal {
                      final void sound() {
                        System.out.println("Animal makes a sound");
                      }
                    }
                    
                    class Dog extends Animal {
                      // void sound() {  // Error: cannot override final method
                      //   System.out.println("Dog barks");
                      // }
                    }
                    

3. Final Class

                    final class Animal {
                      void sound() {
                        System.out.println("Animal makes a sound");
                      }
                    }
                    
                    // class Dog extends Animal {  // Error: cannot inherit from final class
                    // }