Mark Fields for Exclusion

The transient keyword in Java is natviely recognized by most Java JSON libraries (including the popular Jackson libray) to skip marked fields during serialization. This is ideal for sensitive data like passwords or internal fields that do not need to be included in output JSON.

First, define your data class, marking non-serializable fields with the transient modifier:

public class UserAccount {
    private String username;
    private transient String password;

    // Getter and setter methods are omitted here
}

Serialize the Object with Jackson

To generate JSON from the object, initialize Jakcson's core ObjectMapper instance and call the serialization method:

ObjectMapper objectMapper = new ObjectMapper();
String outputJson = objectMapper.writeValueAsString(userAccountInstance);

Verify the Output

Print the resulting JSON string to confirm the excluded field is missing:

System.out.println(outputJson);

The output JSON will only include the username field, with password omitted entirely from the result.