কন্ডিশনাল বা শর্ত (Conditionals)

public class Main {
    public static void main(String[] args) {
        int temperature = 35;

        if (temperature >= 40) {
            System.out.println("Stay inside! It's dangerously hot.");
        } else if (temperature >= 30) {
            System.out.println("It's hot — grab some sunscreen.");
        } else if (temperature >= 20) {
            System.out.println("Nice weather! Perfect for a walk.");
        } else if (temperature >= 10) {
            System.out.println("A bit chilly. Wear a jacket.");
        } else {
            System.out.println("Brrr! Bundle up.");
        }

        // Nested if
        int age = 15;
        boolean hasTicket = true;

        if (age >= 12) {
            if (hasTicket) {
                System.out.println("Welcome to the movie!");
            } else {
                System.out.println("You need a ticket first.");
            }
        } else {
            System.out.println("Sorry, you must be 12 or older.");
        }
    }
}

It's hot — grab some sunscreen.
Welcome to the movie!

public class Main {
    public static void main(String[] args) {
        String day = "Wednesday";

        switch (day) {
            case "Monday":
                System.out.println("Start of the work week.");
                break;
            case "Wednesday":
                System.out.println("Halfway there! Hump day.");
                break;
            case "Friday":
                System.out.println("TGIF! Weekend is near.");
                break;
            case "Saturday":
            case "Sunday":
                System.out.println("Weekend vibes!");
                break;
            default:
                System.out.println("Just another day.");
                break;
        }

        // Ternary — the one-liner if/else
        int score = 72;
        String grade = score >= 90 ? "A" :
                       score >= 80 ? "B" :
                       score >= 70 ? "C" : "F";
        System.out.println("Grade: " + grade);
    }
}

Halfway there! Hump day.
Grade: C

public class Main {
    public static void main(String[] args) {
        String password = "secret123";
        String input = new String("secret123");

        // WRONG way — might not work!
        if (input == password) {
            System.out.println("== says: Match!");
        } else {
            System.out.println("== says: No match!");
        }

        // RIGHT way — always works
        if (input.equals(password)) {
            System.out.println(".equals() says: Match!");
        }

        // Case-insensitive comparison
        String userInput = "ADMIN";
        if (userInput.equalsIgnoreCase("admin")) {
            System.out.println("Welcome, admin!");
        }
    }
}

== says: No match!
.equals() says: Match!
Welcome, admin!