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Switch Statement in Java

The switch statement provides an elegant way to dispatch execution to different parts of code based on the value of an expression.

Supported Types

byte, short, char, int (primitives)
Byte, Short, Character, Integer (wrapper classes)
String (Java 7+)
enum types

⚠️ Important: long, float, double, and boolean are NOT allowed in switch!

Fall-Through Behavior

Without break, execution "falls through" to the next case. This can be intentional or a bug!

Switch Expressions (Java 14+)

Modern Java introduced switch expressions with arrow syntax -> that don't require break and can return values.

💡 Modern Java: Prefer switch expressions over traditional switch statements. They're more concise and less error-prone (no fall-through bugs).

Code Examples

Traditional switch statement with break

java

1// Traditional switch statement
2int day = 3;
3String dayName;
4
5switch (day) {
6    case 1:
7        dayName = "Monday";
8        break;
9    case 2:
10        dayName = "Tuesday";
11        break;
12    case 3:
13        dayName = "Wednesday";
14        break;
15    case 4:
16        dayName = "Thursday";
17        break;
18    case 5:
19        dayName = "Friday";
20        break;
21    default:
22        dayName = "Weekend";
23        break;
24}
25System.out.println(dayName);  // Wednesday

Switch with String and intentional fall-through

java

1// Switch with String (Java 7+)
2String command = "start";
3
4switch (command.toLowerCase()) {
5    case "start":
6        System.out.println("Starting...");
7        break;
8    case "stop":
9        System.out.println("Stopping...");
10        break;
11    case "pause":
12        System.out.println("Pausing...");
13        break;
14    default:
15        System.out.println("Unknown command");
16}
17
18// Fall-through example (intentional)
19int month = 2;
20int days;
21switch (month) {
22    case 1: case 3: case 5: case 7: case 8: case 10: case 12:
23        days = 31;
24        break;
25    case 4: case 6: case 9: case 11:
26        days = 30;
27        break;
28    case 2:
29        days = 28;  // Simplified, ignoring leap year
30        break;
31    default:
32        days = 0;
33}

Modern switch expressions in Java 14+

java

1// Switch Expression (Java 14+) - Arrow syntax
2int day = 3;
3String dayType = switch (day) {
4    case 1, 2, 3, 4, 5 -> "Weekday";
5    case 6, 7 -> "Weekend";
6    default -> "Invalid";
7};
8
9System.out.println(dayType);  // Weekday
10
11// Switch expression with yield (for complex logic)
12String result = switch (day) {
13    case 1, 2, 3, 4, 5 -> {
14        System.out.println("Working day");
15        yield "Weekday";
16    }
17    case 6, 7 -> {
18        System.out.println("Rest day");
19        yield "Weekend";
20    }
21    default -> "Invalid";
22};

Switch with enum types - exhaustiveness checked

java

1// Switch with enum
2enum Status { PENDING, APPROVED, REJECTED, CANCELLED }
3
4Status status = Status.APPROVED;
5
6String message = switch (status) {
7    case PENDING -> "Your request is being processed";
8    case APPROVED -> "Congratulations! Approved!";
9    case REJECTED -> "Sorry, your request was rejected";
10    case CANCELLED -> "Request was cancelled";
11};
12
13// No default needed if all enum values handled!
14System.out.println(message);

Use Cases

Menu-driven programs
State machine implementation
Command pattern dispatch
Enum-based logic
Parsing command-line arguments
Calculator operations

Common Mistakes to Avoid

Forgetting break statements (unintentional fall-through)
Using unsupported types (long, float, double, boolean)
Not handling all enum cases
Duplicate case values
Using non-constant expressions in case labels
Not including default case for non-enum switches