The switch expression, introduced in Java 12 (as a preview feature) and became a standard feature in Java 14, provides a more concise and powerful way to use switch statements. Here’s how to use it effectively:

Key Features of Switch Expressions

1. Simpler Syntax: The new syntax allows the use of the -> syntax to eliminate fall-through behavior.
2. Expression Form: The switch can now return a value directly.
3. Multiple Labels: Multiple case labels can share the same logic using a comma-separated list.
4. No More Breaks: No need for the break keyword after each case.

---

Syntax for Switch Expressions

Here’s a quick breakdown:

String dayType = switch (dayOfWeek) {
    case "Monday", "Tuesday", "Wednesday", "Thursday", "Friday" -> "Weekday";
    case "Saturday", "Sunday" -> "Weekend";
    default -> throw new IllegalArgumentException("Invalid day: " + dayOfWeek);
};

Explanation:

• The -> syntax replaces the colon and break of the traditional switch.
• default acts as a fallback for unmatched cases.
• The result of the switch is assigned directly to the variable dayType.
• Multiple cases separated by commas handle identical conditions.

---

Examples of Switch Expressions

Return a Value Directly from switch

int month = 3;
int daysInMonth = switch (month) {
    case 1, 3, 5, 7, 8, 10, 12 -> 31;
    case 4, 6, 9, 11 -> 30;
    case 2 -> 28; // Use 29 for leap years, this is simplified.
    default -> throw new IllegalArgumentException("Invalid month: " + month);
};
System.out.println("Days in Month: " + daysInMonth);

Using Code Blocks in a Case

For more complex logic, you can use curly braces {} to group multiple statements into a block. In such cases, you must use the yield keyword to specify a value to be returned.

String grade = "B";
String feedback = switch (grade) {
    case "A", "B" -> "Great job!";
    case "C", "D" -> {
        System.out.println("Encouraging message for grade: " + grade);
        yield "Needs improvement.";
    }
    case "F" -> "Failed.";
    default -> throw new IllegalArgumentException("Unknown grade: " + grade);
};
System.out.println("Feedback: " + feedback);

---

Advantages Over Traditional switch

1. No Fall-Through: Avoid accidentally executing multiple cases (common bug with traditional switch).
2. Cleaner Syntax: Easier to read and write due to the arrow operator (->) and elimination of break.
3. Enhanced Type Safety: The returned value must match the expected type assigned to the variable.
4. Pattern Matching (Java 17+): Future extensions allow switch with pattern matching for richer capabilities.

---

Use Cases

1. Assigning values directly with clear logic.
2. Simplifying code structure for multiple conditions or enums.
3. Handling complex branching logic.