Module 9: Object Class & Wrapper Classes

🧱 Object Class

The Object class is the parent class of all Java classes. It provides common methods like:

• toString() – returns a string representation of the object
• equals(Object obj) – checks if two objects are equal
• hashCode() – returns the hash code of the object

                    class Person {
                        String name = "John";
                    
                        public String toString() {
                            return name;
                        }
                    
                        public static void main(String[] args) {
                            Person p = new Person();
                            System.out.println(p.toString()); // John
                        }
                    }
                    

🔢 Wrapper Classes

Wrapper classes convert primitive types into objects. Useful when working with collections like ArrayList.

• int → Integer
• char → Character
• boolean → Boolean
• and so on...

✅ Example: Autoboxing & Unboxing

                    public class Main {
                        public static void main(String[] args) {
                            Integer a = 10;  // autoboxing
                            int b = a;       // unboxing
                            System.out.println(a + b); // 20
                        }
                    }
                    

✅ Converting Strings to Primitives

                    String str = "123";
                    int num = Integer.parseInt(str);
                    System.out.println(num + 1); // 124