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Java / Java 21 Coding Standards Interview Questions

What happens when you omit a break statement in a traditional switch under coding standards?

In a traditional colon-style switch, omitting break causes execution to fall through into the next case's statements, continuing until a break, return, or the end of the switch block is reached - a behavior that is easy to trigger by accident.

switch (level) {
    case LOW:
        System.out.println("low");
        // missing break falls through
    case HIGH:
        System.out.println("high");
        break;
}

Because accidental fall-through is such a common source of bugs, coding standards for Java 21 recommend the arrow-style switch (case LOW -> ...) for new code, since arrow cases never fall through - each case is a self-contained branch with no break needed at all.

When the traditional colon form must be kept for legacy reasons, standards require an explicit // fall through comment on any case that intentionally omits break, so a reviewer can tell a deliberate fall-through from a forgotten one at a glance.

Omitting break in a traditional colon-style switch causes execution to:
Arrow-style switch cases (case X -> ...) are preferred partly because they:

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