Java Control Flow

if / if-else / if-else-if

The if statement executes a block of code only when a condition is true. Chain multiple conditions with else if.

if / else-if / else

public class IfElse {
    public static void main(String[] args) {
        int score = 75;

        if (score >= 90) {
            System.out.println("Grade: A");
        } else if (score >= 80) {
            System.out.println("Grade: B");
        } else if (score >= 70) {
            System.out.println("Grade: C");
        } else if (score >= 60) {
            System.out.println("Grade: D");
        } else {
            System.out.println("Grade: F");
        }
        // Output: Grade: C
    }
}

switch Statement

Use switch when you need to compare a single variable against multiple constant values. Java 14+ introduced the switch expression with arrow syntax — cleaner and no fall-through.

Traditional & Enhanced Switch

public class SwitchDemo {
    public static void main(String[] args) {
        int day = 3;

        // Traditional switch (requires break to prevent fall-through)
        switch (day) {
            case 1: System.out.println("Monday");    break;
            case 2: System.out.println("Tuesday");   break;
            case 3: System.out.println("Wednesday"); break;
            case 4: System.out.println("Thursday");  break;
            case 5: System.out.println("Friday");    break;
            default: System.out.println("Weekend");
        }

        // Enhanced switch expression (Java 14+) — no break needed
        String dayName = switch (day) {
            case 1 -> "Monday";
            case 2 -> "Tuesday";
            case 3 -> "Wednesday";
            case 4 -> "Thursday";
            case 5 -> "Friday";
            default -> "Weekend";
        };
        System.out.println(dayName);  // Wednesday

        // Switch with String
        String season = "SUMMER";
        String activity = switch (season) {
            case "SPRING" -> "Plant flowers";
            case "SUMMER" -> "Go swimming";
            case "AUTUMN" -> "Rake leaves";
            case "WINTER" -> "Build a snowman";
            default -> "Stay home";
        };
        System.out.println(activity);  // Go swimming
    }
}

Ternary Operator

The ternary operator is a compact one-liner for simple if-else assignments: condition ? valueIfTrue : valueIfFalse.

Ternary Operator

public class Ternary {
    public static void main(String[] args) {
        int a = 10, b = 20;

        // Simple ternary
        int max = (a > b) ? a : b;
        System.out.println("Max: " + max);  // 20

        // Nested ternary (use sparingly — hurts readability)
        int num = 0;
        String sign = (num > 0) ? "positive" : (num < 0) ? "negative" : "zero";
        System.out.println(num + " is " + sign);  // 0 is zero

        // Ternary in print
        boolean isLoggedIn = true;
        System.out.println("User is " + (isLoggedIn ? "online" : "offline"));
    }
}

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Java Control Flow

if / if-else / if-else-if

switch Statement

Ternary Operator

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