JSON serialization with Jackson in Spring Boot - Cheat Sheet & Quick Revision

Recall & Review

beginner

What is JSON serialization in the context of Jackson?

JSON serialization is the process of converting Java objects into JSON format using Jackson. It allows data to be easily shared or stored in a readable text format.

beginner

Which Jackson annotation is used to ignore a field during JSON serialization?

The @JsonIgnore annotation is used to tell Jackson to skip a field when converting an object to JSON.

intermediate

How do you customize the JSON property name of a Java field using Jackson?

Use the @JsonProperty("name") annotation on the field or getter method to specify a custom name in the JSON output.

beginner

What is the role of ObjectMapper in Jackson?

ObjectMapper is the main class in Jackson used to convert Java objects to JSON and JSON back to Java objects. It handles the serialization and deserialization process.

intermediate

How can you format dates during JSON serialization with Jackson?

You can use the @JsonFormat annotation on date fields to specify the date pattern, like @JsonFormat(pattern = "yyyy-MM-dd") to control how dates appear in JSON.

Which Jackson annotation prevents a field from appearing in JSON output?

A @JsonFormat

B @JsonProperty

C @JsonInclude

D @JsonIgnore

@JsonIgnore tells Jackson to skip the field during serialization.

What does ObjectMapper do in Jackson?

A Handles HTTP requests

B Manages database connections

C Converts Java objects to JSON and vice versa

D Compiles Java code

ObjectMapper is the core class for JSON serialization and deserialization.

How do you change the JSON key name of a Java field?

A Use @JsonIgnore

B Use @JsonProperty("newName")

C Use @JsonFormat

D Use @JsonInclude

@JsonProperty allows you to rename the JSON key for a field.

Which annotation helps format date fields in JSON?

A @JsonFormat

B @JsonIgnore

C @JsonProperty

D @JsonInclude

@JsonFormat lets you specify date patterns for JSON output.

What format does Jackson produce when serializing objects?

A JSON

B XML

C YAML

D CSV

Jackson serializes Java objects into JSON format.

Explain how Jackson serializes a Java object to JSON and mention key annotations that control this process.

Think about how you convert objects to text and how to hide or rename fields.

Describe how to customize the JSON output for date fields using Jackson.

Consider how dates might look different in JSON and how to control that.