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When to use @JsonValue annotation using Jackson in Java?
The @JsonValue annotation is useful at the method level. We can use this annotation to generate a JSON string from java object. If we want to print a serialized object then override the toString() method. But using @JsonValue annotation, we can define a way in which java object is serialized.
Syntax
@Target(value={ANNOTATION_TYPE,METHOD,FIELD})
@Retention(value=RUNTIME)
public @interface JsonValueExample
import com.fasterxml.jackson.annotation.JsonProperty;
import com.fasterxml.jackson.annotation.JsonValue;
import com.fasterxml.jackson.core.JsonProcessingException;
import com.fasterxml.jackson.databind.ObjectMapper;
import java.io.IOException;
public class JsonValueAnnotationTest {
public static void main(String args[]) throws Exception {
ObjectMapper mapper = new ObjectMapper();
String jsonString = mapper.writeValueAsString(new Student());
System.out.println(jsonString);
}
}
// Student class
class Student {
@JsonProperty
private int studentId = 115;
@JsonProperty
private String studentName = "Sai Adithya";
@JsonValue
public String toJson() {
return this.studentName + "," + this.studentId + "," + this.toString();
}
@Override
public String toString() {
return "Student[" +
"studentId = " + studentId +
", studentName = " + studentName +
']';
}
}Output
"Sai Adithya,115,Student[studentId = 115, studentName = Sai Adithya]"
Updated on: 19-Feb-2020
4K+ Views
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