Core Java

Mastering Jackson’s @Json Annotations: A Developer’s Guide

Jackson is a popular Java library for handling JSON data. It provides a rich set of annotations that can be used to customize the serialization and deserialization process. In this article, we’ll explore five essential @Json annotations that you should be familiar with to effectively work with JSON data in your Java applications.

5 Essential @Json Annotations in Jackson

Jackson offers a wide range of annotations to customize JSON serialization and deserialization. Here are five of the most commonly used and essential ones:

1. @JsonIgnore

  • Purpose: Excludes a field or property from serialization.
  • Usage: Apply this annotation to a field or property to prevent it from being included in the JSON output.
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public class Person {
    @JsonIgnore
    private String password;
    // ...
}

2. @JsonProperty

  • Purpose: Renames a field or property during serialization and deserialization.
  • Usage: Apply this annotation to a field or property and specify the desired JSON name.
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public class Book {
    @JsonProperty("authorName")
    private String author;
    // ...
}

3. @JsonInclude

  • Purpose: Controls the inclusion of null values and empty collections or arrays in the JSON output.
  • Usage: Apply this annotation to a class or field/property with the Include enum to specify the inclusion behavior.
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public class User {
    @JsonInclude(JsonInclude.Include.NON_NULL)
    private String address;
    // ...
}

4. @JsonTypeInfo

  • Purpose: Specifies how to include type information in the JSON output.
  • Usage: Apply this annotation to a class or field/property with the use and include properties to specify the type inclusion strategy.
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@JsonTypeInfo(use = JsonTypeInfo.Id.NAME, include = JsonTypeInfo.As.PROPERTY)
public interface Shape {
    double getArea();
}

5. @JsonCreator

  • Purpose: Specifies a static factory method to be used for deserialization.
  • Usage: Apply this annotation to a static factory method that takes the JSON properties as arguments and returns a new instance of the class.
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public class Person {
    @JsonCreator
    public Person(String name, int age) {
        // ...
    }
}}

Conclusion

Jackson’s @Json annotations are a powerful toolkit for fine-tuning JSON serialization and deserialization in Java. By mastering these annotations, you can create more efficient, flexible, and maintainable JSON-based applications. So, the next time you’re working with JSON data, remember these annotations and unlock their full potential!

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Eleftheria Drosopoulou

Eleftheria is an Experienced Business Analyst with a robust background in the computer software industry. Proficient in Computer Software Training, Digital Marketing, HTML Scripting, and Microsoft Office, they bring a wealth of technical skills to the table. Additionally, she has a love for writing articles on various tech subjects, showcasing a talent for translating complex concepts into accessible content.
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