Deserializing guava optional<long> is failing - jackson

Question

I am serializing a guava optional using jackson(version:2.9.4).
When i am deserializing, i am getting below exception:
Cannot deserialize instance of 'java.lang.Long' out START_OBJECT token.
When i debug the value during deserialization, i noticed that the value is coming as "Optional(present=true)" rather than the value present inside Optional.
I looked at the object mapper, and "GuavaModule()" is already being registered with the object mapper.
Please let me know if i am missing anything.

Answer 1

With registering the GuavaModule of
<dependency>
<groupId>com.fasterxml.jackson.datatype</groupId>
<artifactId>jackson-datatype-guava</artifactId>
</dependency>
…and the following bean…
import com.google.common.base.Optional;
import lombok.Data;
import lombok.NoArgsConstructor;
#Data
#NoArgsConstructor
public class GuavaBean {
private Optional<Long> abc;
}
…this gives me a green test…
import static org.assertj.core.api.Assertions.assertThat;
import com.fasterxml.jackson.datatype.guava.GuavaModule;
[…]
#Test
public void guava() throws JsonParseException, JsonMappingException, IOException {
ObjectMapper objectMapper = new ObjectMapper();
objectMapper.registerModule(new GuavaModule());
GuavaBean bean = new GuavaBean(Optional.of(9l));
String beanSerialized = objectMapper.writeValueAsString(bean);
assertThat(beanSerialized).isEqualTo("{\"abc\":9}");
GuavaBean optLong = objectMapper.readValue(beanSerialized, GuavaBean.class);
assertThat(optLong.getAbc().get()).isEqualTo(9);
}
However, if I accidentally use java.util.Optional instead of com.google.common.base.Optional, then the beahviour is exactly like you wrote.