How to Deserialize JSON into a Generic Class with Jackson?

Deserializing JSON using Generic Types with Jackson

Question: How to deserialize JSON data into a generic class using Jackson?

Consider the following example class:

class Data<T> {
    int found;
    Class<T> hits
}

A standard JSON deserialization attempt using mapper.readValue(jsonString, Data.class) will fail. To correctly deserialize the data, we need to specify the type parameter .

Answer: Jackson provides a TypeReference class to handle generic types during deserialization. To use it:

1. Create a TypeReference object for the generic class. In this example, the type reference for Data would be:

   new TypeReference<Data<String>>() {}

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2. Pass the TypeReference object to the readValue method:

   mapper.readValue(jsonString, new TypeReference<Data<String>>() {});

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This will correctly deserialize the JSON data into an instance of Data.

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