Just read Google's explanation!
TLTR: It gives you immutability (thread safety!), equals(), hashCode() and toString() for free!
Simple example of class annotated with AutoValue or AutoParcel + Jackson.
It is serializable to JSON and deserializable from JSON, it's immutable and it has correctly implemented equals(), hashCode() and toString()! Life is better with AutoValue!
// Just use @AutoParcel annotations if you need AutoParcel
@AutoValue
@JsonSerizalize(as = Tweet.class)
@JsonDeserialize(builder = Tweet.Builder.class)
public abstract class Tweet {
@NotNull
public static Builder builder() {
return Builder.builder();
}
@NotNull
@JsonProperty("author")
public abstract String author();
@NotNull
@JsonProperty("content")
public abstract String content();
@AutoValue.Builder
public static abstract class Builder {
@JsonCreator
public static Builder builder() {
return new AutoValue_Tweet.Builder();
}
@NotNull
@JsonProperty("author")
public abstract Builder author(@NotNull String author);
@NotNull
@JsonProperty("content")
public abstract Builder content(@NotNull String content);
@NotNull
public abstract Tweet build();
}
}Serialization and deserialization:
@Test
public void shouldSerializeToJson() throws JsonProcessingException {
ObjectMapper objectMapper = new ObjectMapper();
Tweet tweet = Tweet.builder()
.author("@artem_zin")
.content("Immutability for everybody!")
.build();
assertThatJson(objectMapper.writeValueAsString(tweet))
.isEqualTo("{\"author\":\"@artem_zin\",\"content\":\"Immutability for everybody!\"}");
}
@Test
public void shouldDeserializeFromJson() throws IOException {
ObjectMapper objectMapper = new ObjectMapper();
String json = "{\"author\":\"@artem_zin\",\"content\":\"Immutability for everybody!\"}";
Tweet tweet = objectMapper.readValue(json, Tweet.class);
assertThat(tweet.author()).isEqualTo("@artem_zin");
assertThat(tweet.content()).isEqualTo("Immutability for everybody!");
}Run sh ci.sh.