Java ObjectMapper readValue vs convertValue

The ObjectMapper class in Jackson provides two methods for converting between JSON and Java objects: readValue() and convertValue().

readValue() is used to convert a JSON string into a Java object. The readValue() method takes two arguments: the JSON string and the class of the Java object to be created.

convertValue() is used to convert a Java object into a JSON string or a JSON tree. The convertValue() method takes three arguments: the Java object to be converted, the desired type of the converted value, and an optional ObjectMapper instance.

The main difference between readValue() and convertValue() is that readValue() is specifically designed for converting JSON strings into Java objects, while convertValue() can be used to convert any Java object into any other type of value.

In general, readValue() should be used when you need to convert a JSON string into a Java object. convertValue() should be used when you need to convert any Java object into any other type of value.

Here is an example of how to use readValue() to convert a JSON string into a Java object:

ObjectMapper mapper = new ObjectMapper();

String jsonString = "{\"name\":\"John Doe\",\"age\":30}";

Person person = mapper.readValue(jsonString, Person.class);

In this example, the ObjectMapper instance is used to convert the JSON string "{\"name\":\"John Doe\",\"age\":30}" into a Person object. The Person class is a simple Java class that represents a person.

Here is an example of how to use convertValue() to convert a Java object into a JSON string:

ObjectMapper mapper = new ObjectMapper();

Person person = new Person("John Doe", 30);

String jsonString = mapper.convertValue(person, String.class);

In this example, the ObjectMapper instance is used to convert the Person object person into a JSON string. The JSON string is returned by the convertValue() method.

I hope this helps! Let me know if you have any other questions.