import com.fasterxml.jackson.core.JsonParser;
import com.fasterxml.jackson.databind.DeserializationContext;
import com.fasterxml.jackson.databind.deser.std.StdScalarDeserializer;

import java.io.IOException;

public class StringDeserializer extends StdScalarDeserializer<String> {

    public StringDeserializer() {
        super(String.class);
    }

    @Override
    public String deserialize(JsonParser parser, DeserializationContext context) throws IOException {
        return parser.getValueAsString();
    }
}

This is an example of a custom deserializer for a String type in Jackson. This class extends StdScalarDeserializer and overrides the deserialize method to handle converting a JSON value to a String instance.

It uses the parser.getValueAsString() method to deserialize the JSON value to a String instance.

You will need to use this deserializer along with ObjectMapper.registerModule() method to register this deserializer to be used by the ObjectMapper.

It is important to notice that this custom deserializer is not necessary as String deserialization is handled by default by the Jackson library.

It is only necessary if you need to implement custom behavior, like handling null values or specific format.