Module 15: Strings

🧵 What is a String?

A String in Java is an object that represents a sequence of characters. Strings are immutable, which means once created, they cannot be changed.

📝 Creating Strings

                    String s1 = "Hello"; // using string literal
                    String s2 = new String("World"); // using new keyword
                    

🔧 Common String Methods

                    String s = "Java Programming";
                    s.length(); // 16
                    s.toUpperCase(); // "JAVA PROGRAMMING"
                    s.toLowerCase(); // "java programming"
                    s.charAt(2); // 'v'
                    s.contains("Pro"); // true
                    s.indexOf("a"); // 1
                    s.substring(5); // "Programming"
                    

🔁 String Comparison

                    String a = "Java";
                    String b = "Java";
                    String c = new String("Java");
                    
                    System.out.println(a == b); // true (same reference)
                    System.out.println(a == c); // false (different reference)
                    System.out.println(a.equals(c)); // true (same content)