Java 11 and 12 – New Features

Defining local variables in a switch branch

It is possible to define variables that are local to a switch branch. To do so, a switch branch can define a block of code to execute for a matching case label. To return the value from the branch, it can include a break statement specifying the value to return. 

Let's modify the code in the preceding example to define a code block, as follows:

class Planet { 
    private static long damage; 
    public void use(SingleUsePlastic plastic) { 
        damage += switch(plastic) { 
            case STRAW -> 10; 
            case BAG -> 11; 
            case SPOON, FORK, KNIFE -> 7; 
            case PLATE -> { 
                                int radius = 20;  // Local variable                                                               
                                break (radius < 10 ? 15 : 20); // Using                                                     // break to return                                                     // a value 
                          } 
            case BOTTLE -> 20; 
        }; 
    } 
} 

The scope and accessibility ...