Conditionals (if-else & switch)

☕ Java Lesson 5 Beginner

Conditionals control program branch paths based on boolean evaluations. Java supports standard if-else blocks, ternary evaluations, and modern switch expressions.

1 Compound Conditionals and Nested structures

Conditional logic uses relational variables to test conditions. If-else structures can be nested inside one another to construct complex flow routes.

2 Classic Switch vs. Modern Java 14+ Switch Expressions

Traditional switch statements use the `case` and `break` syntax. If you omit a `break`, execution falls through to the next case. Java 14 introduced modern Switch Expressions which use the arrow (`->`) syntax. This syntax is clean, prevents fall-through errors, and can return values directly.

Java — Conditionals and Switches ▶ Run Code

public class Main {
    public static void main(String[] args) {
        int score = 85;

        // If-else structure
        if (score >= 90) {
            System.out.println("Grade: A");
        } else if (score >= 80) {
            System.out.println("Grade: B");
        } else {
            System.out.println("Grade: C or below");
        }

        // Ternary operator evaluation
        String result = (score >= 50) ? "Passed" : "Failed";
        System.out.println("Exam Result: " + result);

        // Modern Switch Expression (Java 14+)
        int dayOfWeek = 3;
        String dayName = switch (dayOfWeek) {
            case 1 -> "Monday";
            case 2 -> "Tuesday";
            case 3 -> "Wednesday";
            case 4, 5 -> "Weekend threshold";
            default -> "Invalid Day";
        };
        System.out.println("Day status: " + dayName);
    }
}

3 Code Challenge

Challenge: Write a nested conditional checking if a person is old enough to drive (age 16+) and if they possess a valid license (boolean variable). If they have both, print "Safe to drive". Otherwise, specify why they cannot drive. Add a modern switch expression evaluating a character grade ('A', 'B', 'C') to output descriptive reviews (e.g. 'A' -> "Excellent").