Jackson mapping error

Question

I am having trouble reading my JSON file back to it's respective class. I am using Jackson 2.6.3 API

ObjectMapper objectMapper = new ObjectMapper();

list<Movie>myMovies = objectMapper.readValue(JSONFile,objectMapper.getTypeFactory().constructCollectionType(List.class, Movie.class));

My Movie class

public class Movie {
    private List<String> reviews;
    /*Some more variables here */

    public Movie() { // default constructor 
    }

    public List<String> getReviews(){
        return this.reviews;
    }
    public void setReviews(String review){
        this.reviews.add(review);       
    }
}

Error log

com.fasterxml.jackson.databind.JsonMappingException: N/A (through reference chain: java.util.ArrayList[0]->entity.Movie["reviews"])
    at com.fasterxml.jackson.databind.deser.SettableBeanProperty._throwAsIOE(SettableBeanProperty.java:564)
    at com.fasterxml.jackson.databind.deser.SettableBeanProperty._throwAsIOE(SettableBeanProperty.java:548)
    at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:99)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.vanillaDeserialize(BeanDeserializer.java:258)
    at com.fasterxml.jackson.databind.deser.BeanDeserializer.deserialize(BeanDeserializer.java:125)
    at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:245)
    at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:217)
    at com.fasterxml.jackson.databind.deser.std.CollectionDeserializer.deserialize(CollectionDeserializer.java:25)
    at com.fasterxml.jackson.databind.ObjectMapper._readMapAndClose(ObjectMapper.java:3736)
    at com.fasterxml.jackson.databind.ObjectMapper.readValue(ObjectMapper.java:2658)
    at entity.Movie.loadMovies(Movie.java:427)
    at myPackage.Application.main(Application.java:31)
Caused by: java.lang.NullPointerException
    at entity.Movie.setReviews(Movie.java:45)
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(Unknown Source)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(Unknown Source)
    at java.lang.reflect.Method.invoke(Unknown Source)
    at com.fasterxml.jackson.databind.deser.impl.MethodProperty.deserializeAndSet(MethodProperty.java:97)
    ... 9 more

Sample of my JSON File

[  
   {  
      "movieID":1,
      "title":"13",
      "type":"DIGITAL",
      "status":"COMING SOON",
      "synopsis":null,
      "director":null,
      "mRating":"G",
      "casts":null,
      "showTimes":null,
      "reviews":null,
   }
]

Have you tried serializing only non-null value? Try adding it to your `objectMapper` like this `objectMapper.setSerializationInclusion(Include.NON_NULL)` — dguay, Nov 11 '15 at 16:14
@dguay the OP is deserializing and it's the JSON that has nulls. Will `setSerializationInclusion` affect deserialization ? — Manos Nikolaidis, Nov 11 '15 at 16:20
It won't but it will affect the serialization therefore he won't have `null` value in his JSON object. — dguay, Nov 11 '15 at 16:21
Your setter for reviews should accept a `List` and assign that value to your `reviews` field. Your `reviews` field is otherwise uninitialized. — Sotirios Delimanolis, Nov 11 '15 at 16:31
@SotiriosDelimanolis I guess I cannot change the data type the parameters of setters? — Gavin, Nov 11 '15 at 16:54
You can and you did. It's your internal implementation that is wrong. You've not initialized `reviews`. Jackson has no way to initialize it. It remains `null`. — Sotirios Delimanolis, Nov 11 '15 at 16:56
Follow Jackson conventions. In most circumstances, a property should match the corresponding field type. — Sotirios Delimanolis, Nov 11 '15 at 16:56

Jackson mapping error

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