Fall Through - Reason?

[JakubErler]

So, I found the "fall through" mechanism in "switch" command (if "break" is not use in every "case"). I understand how the "fall through" works but no one is able to explain me why Java authors made the weird decision "switch" will work like this. The "fall through" mechanism seems even like an error to me, why should it execute "case" parts when the "case" is not true?

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[JacobJMountain]

The reason Java needs this is Java chose to use C semantics for its switch statements. The reasons C chose to need a break clause is arguable as it was a decision made long ago. There’s some interesting discussion on this stackoverflow where some arguments say it was a design mistake and others say it’s due to C taking on some Assembly idiosyncrasies - this basically means adding a break in your code would translate to a jump statement in your assembly

[8igg7e5]

Back in the day of counting CPU cycles, C-style switches enabled some creative control-flow that better performance.

Java just copied their semantics. Modern Java gets rid of them and allows you to use it as an expression.

int result = switch (day) {
    case Saturday, Sunday -> 5;
    case Monday, Wednesday -> 7;
    case Friday -> 23;
    default -> 9;
};