Java 11 and 12 – New Features

Using switch expressions

Here's an example of a traditional switch construct that is modifying a variable based on an enum value passed to a method:

enum SingleUsePlastic {STRAW, BAG, SPOON, FORK, KNIFE, PLATE, BOTTLE}; 
 
class Planet { 
    private static long damage; 
    public void use(SingleUsePlastic plastic) { 
        switch(plastic) { 
            case STRAW :    damage += 10; 
                            break; 
            case BAG   :    damage += 11; 
                            break; 
            case SPOON :    damage += 7; 
                            break; 
            case FORK  :    damage += 7; 
                            break; 
            case KNIFE :    damage += 7; 
                            break; 
            case PLATE :    damage += 15; 
                            break; 
            case BOTTLE:    damage = 20; 
                            break; 
        } 
    } 
} 

Let's see how the preceding code changes if we use switch expressions:

damage += switch(plastic) { case STRAW -> 10; case BAG -> 11; case SPOON, FORK, KNIFE -> 7; case PLATE -> 15; case ...