JSON serialization with Jackson in Spring Boot - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to annotate a Java class for JSON serialization using Jackson.

Spring Boot

import com.fasterxml.jackson.annotation.[1];

public class User {
    private String name;
    private int age;

    @JsonProperty("user_name")
    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public int getAge() {
        return age;
    }

    public void setAge(int age) {
        this.age = age;
    }
}

Drag options to blanks, or click blank then click option'

AJsonInclude

BJsonIgnore

CJsonProperty

DJsonFormat

Attempts:

3 left

💡 Hint

Common Mistakes

Using @JsonIgnore instead of @JsonProperty will hide the field from JSON.

Confusing @JsonInclude with @JsonProperty.

The @JsonProperty annotation is used to specify the JSON property name for a Java field or method.

2fill in blank

medium

Complete the code to ignore a field during JSON serialization.

Spring Boot

import com.fasterxml.jackson.annotation.[1];

public class Product {
    private String name;

    @JsonIgnore
    private double cost;

    public String getName() {
        return name;
    }

    public void setName(String name) {
        this.name = name;
    }

    public double getCost() {
        return cost;
    }

    public void setCost(double cost) {
        this.cost = cost;
    }
}

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AJsonIgnore

BJsonProperty

CJsonInclude

DJsonFormat

Attempts:

3 left

💡 Hint

Common Mistakes

Using @JsonProperty instead of @JsonIgnore will not hide the field.

Forgetting to import the correct annotation.

The @JsonIgnore annotation tells Jackson to skip the annotated field during serialization and deserialization.

3fill in blank

hard

Fix the error in the code to include non-null fields only during JSON serialization.

Spring Boot

import com.fasterxml.jackson.annotation.JsonInclude;
import com.fasterxml.jackson.annotation.JsonInclude.Include;

@JsonInclude(Include.[1])
public class Order {
    private String id;
    private String description;

    // getters and setters
}

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ANON_NULL

BALWAYS

CNON_EMPTY

DNON_DEFAULT

Attempts:

3 left

💡 Hint

Common Mistakes

Using ALWAYS will include all fields, even null ones.

Using NON_EMPTY excludes empty collections too, which may not be desired.

Using Include.NON_NULL tells Jackson to serialize only fields that are not null.

4fill in blank

hard

Fill both blanks to format a date field in JSON serialization.

Spring Boot

import com.fasterxml.jackson.annotation.JsonFormat;
import java.util.Date;

public class Event {
    @JsonFormat(shape = JsonFormat.Shape.[1], pattern = "[2]")
    private Date eventDate;

    // getters and setters
}

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ASTRING

Byyyy-MM-dd

Cyyyy/MM/dd

DNUMBER

Attempts:

3 left

💡 Hint

Common Mistakes

Using shape=NUMBER will serialize date as timestamp.

Using wrong date pattern will cause parsing errors.

Using shape=STRING and pattern="yyyy-MM-dd" formats the date as a string in the specified pattern.

5fill in blank

hard

Fill all three blanks to create a custom serializer for a field.

Spring Boot

import com.fasterxml.jackson.databind.annotation.JsonSerialize;
import com.fasterxml.jackson.core.JsonGenerator;
import com.fasterxml.jackson.databind.SerializerProvider;
import com.fasterxml.jackson.databind.ser.std.StdSerializer;
import java.io.IOException;

public class User {
    @JsonSerialize(using = [1].class)
    private String password;

    // getters and setters
}

class [2] extends StdSerializer<String> {
    public [3]() {
        super(String.class);
    }

    @Override
    public void serialize(String value, JsonGenerator gen, SerializerProvider provider) throws IOException {
        gen.writeString("***hidden***");
    }
}

Drag options to blanks, or click blank then click option'

APasswordSerializer

Bserialize

CwriteString

DPasswordEncoder

Attempts:

3 left

💡 Hint

Common Mistakes

Using method names instead of class names in the annotation.

Mismatching class name between annotation and class declaration.

The custom serializer class is named PasswordSerializer and is used in the @JsonSerialize annotation and class declaration.