Many existing switch statements are essentially simulations of switch expressions, where each arm either assigns to a common target variable or
returns a value. Expressing this as a statement is roundabout, repetitive, and error-prone.
Java 14 added support for switch expressions, which provide more succinct and less error-prone version of switch.
Noncompliant code example
void day_of_week(DoW day) {
int numLetters;
switch (day) { // Noncompliant
case MONDAY:
case FRIDAY:
case SUNDAY:
numLetters = 6;
break;
case TUESDAY:
numLetters = 7;
break;
case THURSDAY:
case SATURDAY:
numLetters = 8;
break;
case WEDNESDAY:
numLetters = 9;
break;
default:
throw new IllegalStateException("Wat: " + day);
}
}
int return_switch(int x) {
switch (x) { // Noncompliant
case 1:
return 1;
case 2:
return 2;
default:
throw new IllegalStateException();
}
}
Compliant solution
int numLetters = switch (day) {
case MONDAY, FRIDAY, SUNDAY -> 6;
case TUESDAY -> 7;
case THURSDAY, SATURDAY -> 8;
case WEDNESDAY -> 9;
};
