Java 11 and 12 – New Features

An example

Imagine limiting the sizes of a shirt to some predefined sizes (such as Small, Medium, and Large). The following code shows how you can do that with an enum (Size):

enum Size {SMALL, MEDIUM, LARGE}

Java's coding guidelines recommend using uppercase to define enum constants (such as SMALL). Multiple words in a constant can be separated by using an underscore.

The following code shows how you can use the Size enum in a class, Shirt, to restrict its sizes to constants defined in the Size enum:

class Shirt { 
    Size size;              // instance variable of type Size 
    Color color; 
 
    Shirt(Size size, Color color) {      // Size object with Shirt                                                                                                              // instantiation 
        this.size = size; 
        this.color = color; 
    } 
} 

The instance variable of the Size type in the  ...