How can we convert the Java's toString() Object representation into a JSON Object

• For better viewing experience, ie. indentation, collapsibility features

An Example Java Custom Object (Of Type Person)

Person(firstName=Duke, lastName=Java, age=19, streetAddress=B'`5 CISF "Mujeri Mor" Faridabad, city=JavaTown, state=JA, postalCode=12345, phoneNumbers=[MobilePhoneNumber(mobile=111-111-1111), HomePhoneNumber(home=222-222-2222)], familyMembers=[Person(firstName=Sister, lastName=Young, age=13, streetAddress=Same Address, city=Same, state=Same, postalCode=Same, phoneNumbers=[MobilePhoneNumber(mobile=111-111-1111), HomePhoneNumber(home=222-222-2222)], familyMembers=null, attributes=null, partner=null), Person(firstName=brother, lastName=Old, age=21, streetAddress=Same Address, city=Same, state=Same, postalCode=Same, phoneNumbers=[MobilePhoneNumber(mobile=111-111-1111), HomePhoneNumber(home=222-222-2222)], familyMembers=null, attributes=null, partner=null)], attributes={key_1=value, key 2=123, brother details=Person(firstName=brother, lastName=Old, age=21, streetAddress=Same Address, city=Same, state=Same, postalCode=Same, phoneNumbers=[MobilePhoneNumber(mobile=111-111-1111), HomePhoneNumber(home=222-222-2222)], familyMembers=null, attributes=null, partner=null)}, partner=Person(firstName=Partner, lastName=Same Age, age=21, streetAddress=Same Address, city=Same, state=Same, postalCode=Same, phoneNumbers=[MobilePhoneNumber(mobile=111-111-1111), HomePhoneNumber(home=222-222-2222)], familyMembers=null, attributes=null, partner=null))

Same Above Java Object, Just Indented Manually for better readability

    Person(
        firstName=Duke,
        lastName=Java,
        age=19,
        streetAddress=B'`5 CISF, 'Mujeri Mor', Faridabad,
        city=JavaTown,
        state=JA,
        postalCode=12345,
        phoneNumbers=[
            MobilePhoneNumber(
                mobile=111-111-1111
            ),
            HomePhoneNumber(
                home=222-222-2222
            )
        ],
        familyMembers=[
            Person(
                firstName=Sister,
                lastName=Young,
                age=13,
                streetAddress=Same Address,
                city=Same,
                state=Same,
                postalCode=Same,
                phoneNumbers=[
                    MobilePhoneNumber(
                        mobile=111-111-1111
                    ),
                    HomePhoneNumber(
                        home=222-222-2222
                    )
                ],
                familyMembers=null,
                attributes=null,
                partner=null
            ),
            Person(
                firstName=brother,
                lastName=Old,
                age=21,
                streetAddress=Same Address,
                city=Same,
                state=Same,
                postalCode=Same,
                phoneNumbers=[
                    MobilePhoneNumber(
                        mobile=111-111-1111
                    ),
                    HomePhoneNumber(
                        home=222-222-2222
                    )
                ],
                familyMembers=null,
                attributes=null,
                partner=null
            )
        ],
        attributes={
            key_1=value,
            key 2=123, brother
            details=Person(
                firstName=brother,
                lastName=Old,
                age=21,
                streetAddress=Same Address,
                city=Same,
                state=Same,
                postalCode=Same,
                phoneNumbers=[
                    MobilePhoneNumber(
                        mobile=111-111-1111
                    ),
                    HomePhoneNumber(
                        home=222-222-2222
                    )
                ],
                familyMembers=null,
                attributes=null,
                partner=null
            )
        },
        partner=Person(
            firstName=Partner,
            lastName=Same Age,
            age=21,
            streetAddress=Same Address,
            city=Same,
            state=Same,
            postalCode=Same,
            phoneNumbers=[
                MobilePhoneNumber(
                    mobile=111-111-1111
                ),
                HomePhoneNumber(
                    home=222-222-2222
                )
            ],
            familyMembers=null,
            attributes=null,
            partner=null
        )
    )

How can we convert the above Java representation of Person Object into a JSON format?

• I have tried recursion to solve it, but the number of edge cases that I would need to handle, and it does not give me full confidence that the code will parse all the Java Objects correctly

.

Is there a way, I don't have to write a custom parser for this?

And if I have to write a parser, what could be a good approach to take (either by doing some pre-processing or post-processing) that I don't have to handle lots of corner cases due to which the code becomes hard to understand and maintain for longer run

CodePudding user response：

convert the Java's toString() Object representation into a JSON Object

You wouldn't.

Just convert the object as is (using Jackson, as an example)

ObjectMapper mapper = new ObjectMapper();
Person p =...;

String json = mapper.writeValueAsString(p);

CodePudding user response：

Google's gson has a pretty similar idea. You can modify the default class to string converter to have a pretty print and specify custom type adapters for fields in the class you would want to process further.

    Person duke = new Person("Duke", "Java", 19, " \"name\": \"Bon\", \"streetAddress\": \"355A\" ".getBytes(StandardCharsets.UTF_8));

    Gson PrettyGson = new GsonBuilder()
            .registerTypeAdapter(byte[].class,
                    new JsonSerializer() {
                        @Override
                        public JsonElement serialize(Object src, Type typeOfSrc, JsonSerializationContext context) {
                            String byteFieldVal=new String((byte[])src);

                            //......specify additional transformations including more TypeConverters
                            return new JsonPrimitive(finalByteFieldVal);
                        }
                    })
            .setPrettyPrinting().create();

    String donaldJson = PrettyGson.toJson(duke);

    System.out.println(donaldJson);