How to deserialize a float value with a localized decimal separator with Jackson

Question

The input stream I am parsing with Jackson contains latitude and longitude values such as here:

{
    \"name\": \"pr         


        

Answer 1

With all respect to accepted answer, there is a way to get rid of those @JsonDeserialize annotations.

You need to register the custom deserializer in the ObjectMapper.

Following the tutorial from official web-site you just do something like:

    ObjectMapper mapper = new ObjectMapper();
    SimpleModule testModule = new SimpleModule(
            "DoubleCustomDeserializer",
            new com.fasterxml.jackson.core.Version(1, 0, 0, null))
            .addDeserializer(Double.class, new JsonDeserializer() {
                @Override
                public Double deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException {
                    String valueAsString = jp.getValueAsString();
                    if (StringUtils.isEmpty(valueAsString)) {
                        return null;
                    }

                    return Double.parseDouble(valueAsString.replaceAll(",", "\\."));
                }
            });
    mapper.registerModule(testModule);

If you're using Spring Boot there is a simpler method. Just define the Jackson2ObjectMapperBuilder bean somewhere in your Configuration class:

@Bean
public Jackson2ObjectMapperBuilder jacksonBuilder() {
    Jackson2ObjectMapperBuilder builder = new Jackson2ObjectMapperBuilder();

    builder.deserializerByType(Double.class, new JsonDeserializer() {
        @Override
        public Double deserialize(JsonParser jp, DeserializationContext ctxt) throws IOException {
            String valueAsString = jp.getValueAsString();
            if (StringUtils.isEmpty(valueAsString)) {
                return null;
            }

            return Double.parseDouble(valueAsString.replaceAll(",", "\\."));
        }
    });

    builder.applicationContext(applicationContext);
    return builder;
}

and add the custom HttpMessageConverter to the list of WebMvcConfigurerAdapter message converters:

 messageConverters.add(new MappingJackson2HttpMessageConverter(jacksonBuilder().build()));