JAXB (MOXy)- Unmarshalling null values

Question

I'm having troubles with JSon unmarshalling with JAXB MOXy.

Below is the JSON I want to parse:

{
    "accounts": [{
        "description": "A",
        "balance": 1000,
        "balanceAvailable": 1000
    },
    {
        "description": "B",
        "balance": 1001,
        "balanceAvailable": 1001
    },
    {
        "description": "C",
        "balance": 1002,
        "balanceAvailable": 1002
    }],
    "cardPermissions": null,
    "totalBalanceAvailable": 1046.19
}

The problem here is with the field "cardPermissions".

I'm trying to unmarshal an object which doesn't have "cardPermissions" field (no @XmlElement annotation and class attribute).

JAXB throws a NullPointerException while unmarshalling this string because it is:

"cardPermissions": null

and not:

"cardPermissions": "null"

To accept the null value, I had to add inside my POJO the field cardPermissions (with @XmlElement annotation).

Doing this, also without getters and setters, JAXB can unmarshall the provided JSON correctly.

null and "null" are completely different things but I do not want to include this field inside my POJO, and I have to ignore these null values.

EDIT

If i include the root element ("customerInfo") like this:

{
    "customerInfo": {
        "accounts": [{
            "description": "B",
            "balance": 1000,
            "balanceAvailable": 1000
        },
        {
            "description": "C",
            "balance": 1001,
            "balanceAvailable": 1001
        },
        {
            "description": "D",
            "balance": 1002,
            "balanceAvailable": 1002
        }],
        "cardPermissions": null,
        "totalBalanceAvailable": 1046.19
    }
}

JSON gets parsed correctly, but i do not want to include root when i unmarshall the json.

This is my POJO:

@XmlRootElement(name = "customerInfo")
@XmlAccessorType(XmlAccessType.FIELD)
public class CustomerInfo {

    @XmlElement(name = "name")
    private String firstName;

    @XmlElement(name = "surname")
    private String lastName;

    @XmlElement
    private String customerId;

    @XmlElement
    private String email;

    @XmlElement
    private String cardPermissions; //This field has no getter and setter. I need it in order to parse correctly the JSON without the root node "customerInfo"

    @XmlElement
    private List<Account> accounts;

    public CustomerInfo() {

    }

    public CustomerInfo(String firstName, String lastName, String emailAddress) {

        this.firstName = firstName;
        this.lastName = lastName;
        this.email = emailAddress;
    }

    public String getFullName() {

        return firstName + " " + lastName;
    }

    public String getFirstName() {
        return firstName;
    }

    public void setFirstName(String firstName) {
        this.firstName = firstName;
    }

    public String getLastName() {
        return lastName;
    }

    public void setLastName(String lastName) {
        this.lastName = lastName;
    }

    public String getEmail() {
        return email;
    }

    public void setEmail(String email) {
        this.email = email;
    }

    public List<Account> getAccounts() {
        return accounts;
    }

    public void setAccounts(List<Account> accounts) {
        this.accounts = accounts;
    }

    public String getCustomerId() {
        return customerId;
    }

    public void setCustomerId(String customerId) {
        this.customerId = customerId;
    }
}

Harry Coder Harry Coder · Accepted Answer · 2018-10-02T11:29:45

You have two choices :

Set the attribute required to false in the annotation @XmlElement
Set a value to the attribute name in the annotation @XmlElement of all the other fields and then delete the unwanted field. By doing this, the field will be ignored.

For more and good details go to this old post.

JAXB (MOXy)- Unmarshalling null values

1 Answers