com.google.auto.value

Annotation Type AutoOneOf

@Retention(value=CLASS)
 @Target(value=TYPE)
public @interface AutoOneOf

Specifies that the annotated class is a one-of class, also known as a tagged union. An @AutoOneOf class is very similar to an @AutoValue class, in that its abstract methods define a set of properties. But unlike @AutoValue, only one of those properties is defined in any given instance.

 @AutoOneOf(StringOrInteger.Kind.class)
 public abstract class StringOrInteger {
   public enum Kind {STRING, INTEGER}

   public abstract Kind getKind();

   public abstract String string();
   public abstract int integer();

   public static StringOrInteger ofString(String s) {
     return AutoOneOf_StringOrInteger.string(s);
   }

   public static StringOrInteger ofInteger(int i) {
     return AutoOneOf_StringOrInteger.integer(i);
   }
 }

 String client(StringOrInteger stringOrInteger) {
   switch (stringOrInteger.getKind()) {
     case STRING:
       return "the string '" + stringOrInteger.string() + "'";
     case INTEGER:
       return "the integer " + stringOrInteger.integer();
   }
   throw new AssertionError();
 }

@AutoOneOf is explained in more detail in the user guide.

Author:

Chris Nokleberg, Éamonn McManus

Required Element Summary

Required Elements

Modifier and Type	Required Element and Description
java.lang.Class<? extends java.lang.Enum<?>>	value Specifies an enum that has one entry per variant in the one-of.

Element Detail

value

public abstract java.lang.Class<? extends java.lang.Enum<?>> value

Specifies an enum that has one entry per variant in the one-of.