How to use Jackson to deserialise an array of objects

Solution 1:

First create a mapper :

import com.fasterxml.jackson.databind.ObjectMapper;// in play 2.3
ObjectMapper mapper = new ObjectMapper();

As Array:

MyClass[] myObjects = mapper.readValue(json, MyClass[].class);

As List:

List<MyClass> myObjects = mapper.readValue(jsonInput, new TypeReference<List<MyClass>>(){});

Another way to specify the List type:

List<MyClass> myObjects = mapper.readValue(jsonInput, mapper.getTypeFactory().constructCollectionType(List.class, MyClass.class));

Solution 2:

From Eugene Tskhovrebov

List<MyClass> myObjects = Arrays.asList(mapper.readValue(json, MyClass[].class))

This solution seems to be the best for me.

Solution 3:

For Generic Implementation:

public static <T> List<T> parseJsonArray(String json,
                                         Class<T> classOnWhichArrayIsDefined) 
                                         throws IOException, ClassNotFoundException {
   ObjectMapper mapper = new ObjectMapper();
   Class<T[]> arrayClass = (Class<T[]>) Class.forName("[L" + classOnWhichArrayIsDefined.getName() + ";");
   T[] objects = mapper.readValue(json, arrayClass);
   return Arrays.asList(objects);
}

Solution 4:

First create an instance of ObjectReader which is thread-safe.

ObjectMapper objectMapper = new ObjectMapper();
ObjectReader objectReader = objectMapper.reader().forType(new TypeReference<List<MyClass>>(){});

Then use it :

List<MyClass> result = objectReader.readValue(inputStream);