# How to Ignore Null Fields with Jackson in Java

By Atta Ur Rehman Shah (https://attacomsian.com/about). Published Nov 16, 2019, updated Oct 14, 2022. Topics: Java, JSON, Jackson.
Canonical URL: https://attacomsian.com/blog/jackson-ignore-null-fields

> A short tutorial to learn how to ignore null fields while serializing with Jackson on class level as well as globally.

In this short tutorial, you'll learn how to use the [Jackson](https://attacomsian.com/blog/jackson-read-write-json)'s `@JsonInclude` annotation to ignore null fields while [serializing a Java Object](https://attacomsian.com/blog/jackson-convert-java-object-to-from-json) to its JSON representation.

By default, Jackson includes null fields when we serialize a Java Object to its JSON representation. For a deeper understanding, let us create a simple `User` class:

```java
public class User {

    public String name;
    public String email;
    private String[] roles;
    private boolean admin;

    public User() {
    }

    public User(String name, String email, String[] roles, boolean admin) {
        this.name = name;
        this.email = email;
        this.roles = roles;
        this.admin = admin;
    }

    // getters and setters, toString() .... (omitted for brevity)
}
```

Now let us create an instance of `User` and then try to convert it into a JSON string:

```java
try {
    // create user object
    User user = new User("John Doe", null, null, true);

    // convert user object to JSON
    String json = new ObjectMapper().writeValueAsString(user);

    // print JSON string
    System.out.println(json);

} catch (Exception ex) {
    ex.printStackTrace();
}
```

As you can see above, we set the `email` and `roles` fields to null while creating a new user object. Here is the JSON string generated by the above code:

```json
{"name":"John Doe","email":null,"roles":null,"admin":true}
```

To remove null fields from the generated JSON, just put `@JsonInclude` on the class level, field level, or globally.

## Ignore Null Fields on Class Level

To ignore all null fields for a specific class, put the `@JsonInclude` annotation on top of the class name:

```java
@JsonInclude(JsonInclude.Include.NON_NULL)
public class User {
    // ...
}
```

Now, if you run the above example code, you should see that no null fields are a part of the final JSON output:

```json
{"name":"John Doe","admin":true}
```

## Ignore Null Fields on Field Level

You can even specify the `@JsonInclude` annotation on the field level for more granular control:

```java
public class User {

    public String name;
    @JsonInclude(JsonInclude.Include.NON_NULL)
    public String email;
    @JsonInclude(JsonInclude.Include.NON_NULL)
    private String[] roles;
    private boolean admin;

    // ....
}
```

## Ignore Null Fields Globally

Jackson also allows us to configure null fields behavior globally on the `ObjectMapper` instance, as shown below:

```java
try {
    // create user object
    User user = new User("John Doe", null, null, true);

    // create object mapper instance
    ObjectMapper mapper = new ObjectMapper();

    // configure null fields behavior
    mapper.setSerializationInclusion(JsonInclude.Include.NON_NULL);

    // convert user object to JSON
    String json = mapper.writeValueAsString(user);

    // print JSON string
    System.out.println(json);

} catch (Exception ex) {
    ex.printStackTrace();
}
```

Here is the final JSON generated by the above example:

```json
{"name":"John Doe","admin":true}
```

For more Jackson examples, check out the [How to read and write JSON using Jackson in Java](https://attacomsian.com/blog/jackson-read-write-json) tutorial.