switch Statements and Expressions

Overview

Java has two forms of switch:

Both support the traditional colon (:) syntax and the newer arrow (->) syntax.

switch Statement — Colon Syntax

java
int day = 3;

switch (day) {
    case 1:
        System.out.println("Monday");
        break;
    case 2:
        System.out.println("Tuesday");
        break;
    case 3:
        System.out.println("Wednesday");
        break;
    default:
        System.out.println("Other");
}

Fall-through: Without break, execution continues into the next case.

java
switch (day) {
    case 1:
    case 2:
    case 3:
    case 4:
    case 5:
        System.out.println("Weekday");
        break;
    case 6:
    case 7:
        System.out.println("Weekend");
}

switch Statement — Arrow Syntax

Arrow cases do not fall through:

java
switch (day) {
    case 1 -> System.out.println("Monday");
    case 2 -> System.out.println("Tuesday");
    case 3 -> System.out.println("Wednesday");
    default -> System.out.println("Other");
}

Multiple labels per arrow case:

java
switch (day) {
    case 1, 2, 3, 4, 5 -> System.out.println("Weekday");
    case 6, 7           -> System.out.println("Weekend");
}

switch Expression — Arrow Syntax

A switch expression produces a value and must be exhaustive (all possible values covered):

java
String name = switch (day) {
    case 1 -> "Monday";
    case 2 -> "Tuesday";
    case 3 -> "Wednesday";
    case 4 -> "Thursday";
    case 5 -> "Friday";
    case 6 -> "Saturday";
    case 7 -> "Sunday";
    default -> throw new IllegalArgumentException("Invalid day: " + day);
};

switch Expression — Colon Syntax with yield

Use yield to return a value from a colon-style switch expression block:

java
int numLetters = switch (day) {
    case 1, 2, 3, 4, 5, 6 -> day + 5;  // simple arrow
    case 7 -> {
        System.out.println("Computing Sunday...");
        yield 6;  // yield required in a block
    }
    default -> 0;
};

yield vs return: yield exits the switch block with a value; return exits the enclosing method.

Allowed Selector Types

Exhaustiveness

• A switch statement does not need to be exhaustive — missing cases are simply skipped.
• A switch expression must be exhaustive — the compiler enforces this. Use default or cover all enum constants.

Key Rules Summary