Java 11 and 12 – New Features

Decompiled enum – behind the scenes

Every user-defined enum implicitly extends the java.lang.Enum class. Behind the scenes, the one-line Size enum (defined in the preceding section) is compiled into something similar to the following (I've added comments in the code to explain it; when you compile an enum, you won't get similar comments):

final class Size extends Enum                 // 'enum' converted to final class  
{ 
    public static final Size SMALL;           // variables to store  
    public static final Size MEDIUM;          // enum constants 
    public static final Size LARGE;           //  
 
    private static final Size $VALUES[];    // array of all enum                                             // constants 
 
    static 
    {                                       // static initializer 
        SMALL = new Size("SMALL", 0);       // to initialize enum                                                                                              // constants MEDIUM = new Size("MEDIUM", 1); ...