Develop Reference

Java Builder Object Printing Null

I have created a Person, class and a Professor class that both use the Builder Pattern to create objects. The Professor class takes a Person object as an argument in its constructor. I am trying to use both classes together, but when I attempt to print out a professor, get the following output: null null (instead of Bob Smith).
Here's what I tried so far:
Person:
public class Person {
private String firstname;
private String lastname;
private int age;
private String phoneNumber;
private String emailAddress;
private char gender;
public Person(){}
// builder pattern chosen due to number of instance fields
public static class PersonBuilder {
// required parameters
private final String firstname;
private final String lastname;
// optional parameters
private int age;
private String phoneNumber;
private String emailAddress;
private char gender;
public PersonBuilder(String firstname, String lastname) {
this.firstname = firstname;
this.lastname = lastname;
}
public PersonBuilder age(int age) {
this.age = age;
return this;
}
public PersonBuilder phoneNumber(String phoneNumber) {
this.phoneNumber = phoneNumber;
return this;
}
public PersonBuilder emailAddress(String emailAddress) {
this.emailAddress = emailAddress;
return this;
}
public PersonBuilder gender(char gender) {
this.gender = gender;
return this;
}
public Person build() {
return new Person(this);
}
}
// person constructor
private Person(PersonBuilder builder) {
this.firstname = builder.firstname;
this.lastname = builder.lastname;
this.age = builder.age;
this.phoneNumber = builder.phoneNumber;
this.emailAddress = builder.emailAddress;
this.gender = builder.gender;
}
#Override
public String toString() {
return this.firstname + " " + this.lastname;
}
}
Here's the Professor class:
package com.example.hardcodedloginform;
import java.util.List;
public class Professor extends Person{
private Person professor;
private double salary;
private String courseTaught;
private List<Student> students;
private int professorID;
public static class ProfessorBuilder {
// required fields
private Person professor;
private int professorID;
// optional fields
private double salary;
private String courseTaught;
private List<Student> students;
public ProfessorBuilder(Person professor, int professorID) {
this.professor = professor;
this.professorID = professorID;
}
public ProfessorBuilder salary(double salary) {
this.salary = salary;
return this;
}
public ProfessorBuilder courseTaught(String courseTaught) {
this.courseTaught = courseTaught;
return this;
}
public ProfessorBuilder students(List<Student> students) {
this.students = students;
return this;
}
public Professor build() {
return new Professor(this);
}
}
private Professor(ProfessorBuilder builder) {
this.salary = builder.salary;
this.courseTaught = builder.courseTaught;
this.students = builder.students;
}
#Override
public String toString() {
return "" + super.toString();
}
}
And here is the Main class where I try to print out a professor object:
public class Main {
public static void main(String[] args) {
Person profBobs = new Person.PersonBuilder("Bob", "Smith")
.age(35)
.emailAddress("bob.smith#SNHU.edu")
.gender('M')
.phoneNumber("818-987-6574")
.build();
Professor profBob = new Professor.ProfessorBuilder(profBobs, 12345)
.courseTaught("MAT101")
.salary(15230.01)
.build();
System.out.println(profBob);
}
}
I would like the printout in the console to be "Bob Smith", but what I am seeing is: null null. I checked and found that the Person object profBobs is, in fact, created properly and does print out the name "Bob Smith" when I attempt to print it the same way. I don't know why my Professor prints: null null.

Your Professor constructor fails to initialise any member fields of its base class.
There are multiple ways to solve this. One solution has ProfessorBuilder extend PersonBuilder:
public class Professor extends Person {
// Remove the `person` field! A professor *is-a* person, it does not *contain* it.
private double salary;
private String courseTaught;
private List<Student> students;
private int professorID;
public static class ProfessorBuilder extends Person.PersonBuilder {
// required fields
private int professorID;
// optional fields
private double salary;
private String courseTaught;
private List<Student> students;
public ProfessorBuilder(Person professor, int professorID) {
super(professor);
this.professorID = professorID;
}
// …
}
private Professor(ProfessorBuilder builder) {
super(builder);
this.salary = builder.salary;
this.courseTaught = builder.courseTaught;
this.students = builder.students;
}
}
For this to work you also need to mark the Person constructor as protected rather than private.
Furthermore, your Professor.toString method implementation made no sense: it essentially just called the base class method, so there’s no need to override it. And prepending the empty string does nothing.

Spring batch IllegalStateException for updates

I'm fairly new to Spring, and coding in general. I want to build an application from which a user can update existing records in a database from a CSV file. I'm using spring batch to do so, but when I execute the test, I get the famous:
java.lang.IllegalStateException: Existing transaction detected in JobRepository. Please fix this and try again (e.g. remove #Transactional annotations from client).
If I remove the #Transactional, I get this error instead:
org.springframework.dao.InvalidDataAccessApiUsageException: org.hibernate.hql.internal.QueryExecutionRequestException: Not supported for DML operations [UPDATE com.example.testApp.Models.Person p SET p.address = p.address, p.country = p.country, p.cellphone = p.cellphone, p.city = p.city, p.phone = p.cellphone, p.email = p.email, p.age = p.age WHERE p.pplId IN (:ids_0, :ids_1, :ids_2, :ids_3, :ids_4, :ids_5, :ids_6, :ids_7, :ids_8, :ids_9, :ids_10)]
I've looked around some other solutions here, but they don't seem to work for what I want to do. I'm aware that hibernate supports batch updates, but again, I'm not sure how to make it work with what I already have.
Here's my test class (obviously with just the method I've been having problems with):
#SpringBootTest
public class PersonTests {
#Autowired
private PeopleRepository peopleRepository;
#Autowired
JobLauncher jobLauncher;
#Autowired
Job peopleInsertJob; //Separate job for inserting from a CSV file
#Autowired
Job peopleUpdateJob;
#Order(4) //executes after the insert from CSV test, for obvious reasons.
#Test
public void updateRecordsFromCsvFile() throws Exception {
Map<String, JobParameter> maps = new HashMap<>();
maps.put("time", new JobParameter(System.currentTimeMillis()));
JobParameters parameters = new JobParameters(maps);
JobExecution jobExecution = jobLauncher.run(peopleUpdateJob, parameters);
assertEquals("COMPLETED", jobExecution.getStatus().name());
}
}
Here's my Batch configuration file for the update:
#Bean
public Job peopleUpdateJob(JobBuilderFactory jobBuilderFactory,
StepBuilderFactory stepBuilderFactory,
ItemReader<Person> itemReaderForUpdate,
ItemProcessor<Person, Person> itemProcessor,
#Qualifier("DBPeopleUpdater") ItemWriter<Person> itemUpdater)
{
Step step = stepBuilderFactory.get("ETL-file-load")
.<People, People>chunk(100)
.reader(itemReaderForUpdate)
.processor(itemProcessor)
.writer(itemUpdater)
.build();
return jobBuilderFactory.get("ETL-Load")
.incrementer(new RunIdIncrementer())
.start(step)
.build();
}
#Bean
public FlatFileItemReader itemReaderForUpdate() throws Exception
{
FlatFileItemReader<Person> flatFileItemReader = new FlatFileItemReader<>();
flatFileItemReader.setResource(new FileSystemResource("src/main/resources/CSV/TestFilePeople-UpdateBatch.csv"));
flatFileItemReader.setName("PeopleCSV-Update-Reader");
flatFileItemReader.setLinesToSkip(1);
flatFileItemReader.setLineMapper(lineMapper());
return flatFileItemReader;
}
#Bean
public LineMapper<Person> lineMapper()
{
DefaultLineMapper<Person> defaultLineMapper = new DefaultLineMapper<>();
DelimitedLineTokenizer lineTokenizer = new DelimitedLineTokenizer();
lineTokenizer.setDelimiter(",");
lineTokenizer.setStrict(false);
lineTokenizer.setNames("Id","lastname", "lastname2", "firstname",
"midname","phone", "cellphone", "email", "status", "address", "city", "region", "country");
BeanWrapperFieldSetMapper<Person> fieldSetMapper = new BeanWrapperFieldSetMapper<>();
fieldSetMapper.setTargetType(Person.class);
defaultLineMapper.setLineTokenizer(lineTokenizer);
defaultLineMapper.setFieldSetMapper(fieldSetMapper);
return defaultLineMapper;
}
This is the ItemWriter I'm using for the update:
#Component
public class DBPeopleUpdater implements ItemWriter<Person> {
#Autowired
PeopleRepository peopleRepository;
#Override
public void write(List<? extends Person> list) throws Exception
{
List<String> pplIds = new ArrayList<>();
for(People p : list)
{
pplIds.add(p.getpplId());
}
peopleRepository.updatePersonsByIdIsIn(pplIds);
}
}
This is the method that I'm using from my PeopleRepository. It's the only method I have. My repository is extends CrudRepository:
#Modifying
#Query("UPDATE Person p SET p.address= p.address, p.country = p.country," +
"p.cellphone = p.cellphone, p.city = p.city, p.phone = p.cellphone," +
"p.email = p.email, p.status = p.status WHERE p.pplId IN :ids")
List<Person>updatePersonsByPplIdIsIn(List<String> ids);
I'm mapping my Person class as an entity that connects to a PostgreSQL database table. I don't have any local sql files in my project. I have no other tables in the database.
If it's not possible to solve this using spring batch, if you could guide me towards jpa/hibernate resources I could use to understand how to solve this problem, I would really appreciate it.
EDIT
Here's the code for the entity
#Entity
#Table(name = "people", schema = "example_schema")
public class Person {
#NonNull
#Id
#Column(name = "ppl_id")
private String pplId;
#Column(name = "ppl_last_name")
private String lastname;
#Column(name = "ppl_sec_last_name")
private String lastname2;
#Column(name = "ppl_first_name")
private String firstname;
#Column(name = "ppl_mid_name")
private String midname;
#Column(name = "ppl_phone_no")
private String phone;
#Column(name = "ppl_cell_no")
private String cellphone;
#Column(name = "ppl_corp_email")
private String email;
#Column(name="ppl_status")
private String status;
#Column(name="ppl_address")
private String address;
#Column(name="ppl_city")
private String city;
#Column(name="ppl_region")
private String region;
#Column(name="ppl_country")
private String country;
//Default constructor
public Person()
{
super();
}
public Person(#NonNull String pplId, String lastname, String lastname2, String firstname, String midname, String phone, String cellphone, String email, String status, String address, String city, String region, String country) {
this.pplId = pplId;
this.lastname = lastname;
this.lastname2 = lastname2;
this.firstname = firstname;
this.midname = midname;
this.phone = phone;
this.cellphone = cellphone;
this.email = email;
this.status = status;
this.address = address;
this.city = city;
this.region = region;
this.country = country;
}
public String getPplId() {
return pplId;
}
public void setWrkId(String pplId) {
this.pplId = pplId;
}
public String getLastname() {
return lastname;
}
public void setLastname(String lastname) {
this.lastname = lastname;
}
public String getLastname2() {
return lastname2;
}
public void setLastname2(String lastname2) {
this.lastname2 = lastname2;
}
public String getFirstname() {
return firstname;
}
public void setFirstname(String firstname) {
this.firstname = firstname;
}
public String getMidname() {
return midname;
}
public void setMidname(String midname) {
this.midname = midname;
}
public String getPhone() {
return phone;
}
public void setPhone(String phone) {
this.phone = phone;
}
public String getCellphone() {
return cellphone;
}
public void setCellphone(String cellphone) {
this.cellphone = cellphone;
}
public String getEmail() {
return email;
}
public void setEmail(String email) {
this.email = email;
}
public String getStatus() {
return status;
}
public void setStatus(String status) {
this.status = status;
}
public String getAddress() {
return address;
}
public void setAddress(String address) {
this.address = address;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
public String getRegion() {
return region;
}
public void setRegion(String region) {
this.region = region;
}
public String getCountry() {
return country;
}
public void setCountry(String country) {
this.country = country;
}

#JsonMerge with list of objects and builder

I am trying to merge JSON objects with the new #JsonMerge annotation. I found a sample online that works when I run it in my IDE. Here's a snippet to run:
#Test
void mergeTest() throws IOException {
final Employee employee = new Employee("Serializon", new Address("Street 1", "City 1", "ZipCode1"));
final Employee newEmployee = new Employee("Serializon", new Address("Street 2", "City 2", "ZipCode2"));
assertThat(employee.getAddress().getCity()).isEqualTo("City 1");
final ObjectMapper objectMapper = new ObjectMapper();
final Employee mergedEmployee = objectMapper.readerForUpdating(employee).readValue(JSONUtil.toJSON(newEmployee));
System.out.println(objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(mergedEmployee));
assertThat(newEmployee.getAddress().getCity()).isEqualTo("City 2");
assertThat(mergedEmployee.getAddress().getCity()).isEqualTo("City 2");
}
public class Employee {
private String name;
#JsonMerge
private Address address;
public Employee(final String name, final Address address) {
this.name = name;
this.address = address;
}
public String getName() {
return name;
}
public Address getAddress() {
return address;
}
}
public class Address {
private String street;
private String city;
private String zipCode;
public Address(final String street, final String city, final String zipCode) {
this.street = street;
this.city = city;
this.zipCode = zipCode;
}
public String getStreet() {
return street;
}
public String getCity() {
return city;
}
public String getZipCode() {
return zipCode;
}
}
When I try to reproduce this with my own class, it fails with the following error:
Deserialization of [simple type, class package.State] by passing existing instance (of package.State) not supported
My class in question is a POJO with some lists and primitive properties, all with getters. It is constructed using a builder and is immutable. It looks like this:
#JsonDeserialize(builder = State.Builder.class)
public class State {
private final String id;
#JsonMerge
private final List<Module> modules;
protected State(final Builder builder) {
this.id = builder.id;
this.modules = builder.modules;
}
public static Builder builder() {
return new Builder();
}
public String getId() {
return id;
}
public List<Module> getModules() {
return modules;
}
#JsonIgnoreProperties(ignoreUnknown = true)
public static final class Builder {
private String id;
private List<Module> modules;
private Builder() {
}
public Builder withId(final String id) {
this.id = id;
return this;
}
public Builder withModules(final List<Module> modules) {
this.modules = modules;
return this;
}
public State build() {
return new State(this);
}
}
}
The merge annotation states the following:
Merging is only option if there is a way to introspect current state: if there is accessor (getter, field) to use. Merging can not be enabled if no accessor exists or if assignment occurs using a Creator setter (constructor or factory method), since there is no instance with state to introspect.
So I thought perhaps the builder might the problem, but retrofitting the Employee/Address sample with a builder still works:
#Test
void mergeTest() throws IOException {
final Employee employee = Employee.newBuilder()
.withName("Serializon")
.withAddress(Address.newBuilder()
.withStreet("Steet 1")
.withCity("City 1")
.withZipCode("ZipCode1")
.build())
.build();
assertThat(employee.getAddress().getCity()).isEqualTo("City 1");
final Employee newEmployee = Employee.newBuilder()
.withName("Serializon")
.withAddress(Address.newBuilder()
.withStreet("Steet 2")
.withCity("City 2")
.withZipCode("ZipCode2")
.build())
.build();
final ObjectMapper objectMapper = new ObjectMapper();
final Employee mergedEmployee = objectMapper.readerForUpdating(employee).readValue(JSONUtil.toJSON(newEmployee));
System.out.println(objectMapper.writerWithDefaultPrettyPrinter().writeValueAsString(mergedEmployee));
assertThat(newEmployee.getAddress().getCity()).isEqualTo("City 2");
assertThat(mergedEmployee.getAddress().getCity()).isEqualTo("City 2");
}
#JsonDeserialize(builder = Employee.Builder.class)
public class Employee {
private String name;
#JsonMerge
private Address address;
private Employee(final Builder builder) {
name = builder.name;
address = builder.address;
}
public static Builder newBuilder() {
return new Builder();
}
public String getName() {
return name;
}
public Address getAddress() {
return address;
}
public static final class Builder {
private String name;
private Address address;
private Builder() {
}
public Builder withName(final String name) {
this.name = name;
return this;
}
public Builder withAddress(final Address address) {
this.address = address;
return this;
}
public Employee build() {
return new Employee(this);
}
}
}
#JsonDeserialize(builder = Address.Builder.class)
public class Address {
private String street;
private String city;
private String zipCode;
private Address(final Builder builder) {
street = builder.street;
city = builder.city;
zipCode = builder.zipCode;
}
public static Builder newBuilder() {
return new Builder();
}
public String getStreet() {
return street;
}
public String getCity() {
return city;
}
public String getZipCode() {
return zipCode;
}
public static final class Builder {
private String street;
private String city;
private String zipCode;
private Builder() {
}
public Builder withStreet(final String street) {
this.street = street;
return this;
}
public Builder withCity(final String city) {
this.city = city;
return this;
}
public Builder withZipCode(final String zipCode) {
this.zipCode = zipCode;
return this;
}
public Address build() {
return new Address(this);
}
}
}
Finally I tried to have a list of addresses instead, and accepting the list in the builder as withAddresses instead. So, for brevity:
#JsonDeserialize(builder = Employee.Builder.class)
public class Employee {
#JsonMerge
private List<Address> addresses;
public static final class Builder {
public Builder withAddresses(final List<Address> addresses) {
this.addresses = addresses;
return this;
}
}
}
And when I run the testcase again, this fails with the same error as my own code:
Deserialization of [simple type, class se.itab.locker.core.util.Employee] by passing existing instance (of se.itab.locker.core.util.Employee) not supported
What is actually going on here, and can I resolve it somehow or is this an unsupported use case or bug?
Update
So I found that this works:
//#JsonDeserialize(builder = Employee.Builder.class)
public class Employee {
#JsonCreator
public Employee(final Employee employee) {
name = employee.name;
addresses = employee.addresses;
stringAddresses = employee.stringAddresses;
}
But then serializing causes an infinite loop instead.

Firestore Add Custom Objects with Reference Attribute

I have been adding POJOs to Firestore that automatically interprets them as JSON objects for the database. However I want to have one of my POJOs have what Firestore calls a reference type. Would the attribute type just be DocumentReference instead of a String?
I'm working on an Android project using Java.
Here is the custom object example from the Firebase Docs.
public class City {
private String name;
private String state;
private String country;
private boolean capital;
private long population;
private List<String> regions;
public City() {}
public City(String name, String state, String country, boolean capital, long population, List<String> regions) {
// ...
}
public String getName() {
return name;
}
public String getState() {
return state;
}
public String getCountry() {
return country;
}
public boolean isCapital() {
return capital;
}
public long getPopulation() {
return population;
}
public List<String> getRegions() {
return regions;
}
}
Then to add to the database
City city = new City("Los Angeles", "CA", "USA",
false, 5000000L, Arrays.asList("west_coast", "sorcal"));
db.collection("cities").document("LA").set(city);

I've done some simple testing and figured it out.
The attribute type is indeed DocumentReference for custom objects when adding directly to Firestore.
Here is an example where the creator of a Group is a reference to a user in the database:
//Class POJO that holds data
public class Group {
private String name;
private DocumentReference creator;
public Group(){}
public Group(String name, DocumentReference ref) {
this.name = name;
this.creator = ref;
}
public String getName() { return this.name; }
public DocumentReference getCreator() { return this.creator; }
}
// Add to database
String uid = FirebaseAuth.getInstance().getCurrentUser().getUid();
DocumentReference ref = db.collection("users").document(uid);
Group newGroup = new Group("My Group", ref);
db.collection("groups").document().set(newGroup);

Jackson JSON, Immutable Classes, and Interfaces

I am playing with the Jackson examples and am having some trouble getting deserialization to work with immutable classes and interfaces.
Below is my code:
package com.art.starter.jackson_starter;
import java.io.IOException;
import java.io.StringReader;
import java.io.StringWriter;
import org.codehaus.jackson.JsonGenerationException;
import org.codehaus.jackson.map.JsonMappingException;
import org.codehaus.jackson.map.ObjectMapper;
/** * Hello world! * */ public class App {
public static void main( String[] args ) throws JsonGenerationException, JsonMappingException, IOException
{
System.out.println( "Hello World!" );
AddressImpl.AddressBuilder builder = new AddressImpl.AddressBuilder();
NameImpl.Builder nameBuilder = new NameImpl.Builder();
UserImpl.Builder userBuilder = new UserImpl.Builder();
Name name = nameBuilder.first("FirstName")
.last("LastName")
.build();
Address address = builder.setCity("TestCity")
.setCountry("TestCountry")
.setState("PA")
.setStreet("TestAddress")
.setZip(123)
.build();
User user = userBuilder.address(address)
.gender(User.Gender.MALE)
.isVerified(true)
.userImage(new byte[5])
.build();
System.out.println(address);
System.out.println(name);
System.out.println(user);
StringWriter sw = new StringWriter();
ObjectMapper mapper = new ObjectMapper();
mapper.writeValue(sw, user);
System.out.println(sw);
StringReader sr = new StringReader("{\"address\":{\"state\":\"PA\",\"country\":\"TestCountry\",\"street\":\"TestAddress\",\"city\":\"TestCity\",\"zip\":123},\"verified\":true,\"gender\":\"MALE\",\"userImage\":\"AAAAAAA=\"}");
/*
This line throws the Exception
*/
User user2 = mapper.readValue(sr, UserImpl.class);
System.out.println(user2);
} }
package com.art.starter.jackson_starter;
import java.util.Arrays;
import org.codehaus.jackson.annotate.JsonCreator;
import org.codehaus.jackson.annotate.JsonProperty;
public final class UserImpl implements User
{
private final Address address;
private final Gender gender;
private final byte[] userImage;
private final boolean isVerified;
public static class Builder
{
private Address address;
private Gender gender;
// private Name name;
private byte[] userImage;
private boolean isVerified;
public Builder address(Address address)
{
this.address = address;
return this;
}
public Builder gender(Gender gender)
{
this.gender = gender;
return this;
}
// public Builder name(Name name)
// {
// this.name = name;
// return this;
// }
public Builder userImage(byte[] userImage)
{
this.userImage = userImage;
return this;
}
public Builder isVerified(boolean isVerified)
{
this.isVerified = isVerified;
return this;
}
public UserImpl build()
{
return new UserImpl(address, gender, userImage, isVerified);
}
}
#JsonCreator
public UserImpl(#JsonProperty("address") Address address, #JsonProperty("gender") Gender gender, #JsonProperty("userImage") byte[] userImage,
#JsonProperty("verified") boolean isVerified)
{
super();
this.address = address;
this.gender = gender;
this.userImage = userImage;
this.isVerified = isVerified;
}
public Address getAddress()
{
return address;
}
public Gender getGender()
{
return gender;
}
public byte[] getUserImage()
{
return userImage;
}
public boolean isVerified()
{
return isVerified;
}
#Override
public String toString()
{
StringBuilder builder2 = new StringBuilder();
builder2.append("UserImpl [address=");
builder2.append(address);
builder2.append(", gender=");
builder2.append(gender);
builder2.append(", isVerified=");
builder2.append(isVerified);
builder2.append(", name=");
builder2.append(", userImage=");
builder2.append(Arrays.toString(userImage));
builder2.append("]");
return builder2.toString();
}
}
package com.art.starter.jackson_starter;
import org.codehaus.jackson.annotate.JsonCreator;
import org.codehaus.jackson.annotate.JsonProperty;
public final class AddressImpl implements Address
{
private final String city;
private final String country;
private final String street;
private final String state;
private final int zip;
public static class AddressBuilder
{
private String city;
private String country;
private String street;
private String state;
private int zip;
public AddressBuilder setCity(String city)
{
this.city = city;
return this;
}
public AddressBuilder setCountry(String country)
{
this.country = country;
return this;
}
public AddressBuilder setStreet(String street)
{
this.street = street;
return this;
}
public AddressBuilder setState(String state)
{
this.state = state;
return this;
}
public AddressBuilder setZip(int zip)
{
this.zip = zip;
return this;
}
public AddressImpl build()
{
return new AddressImpl(city, country, street, state, zip);
}
}
#JsonCreator
public AddressImpl(#JsonProperty("city") String city, #JsonProperty("country") String country, #JsonProperty("street") String street,
#JsonProperty("state") String state, #JsonProperty("zip") int zip)
{
this.city = city;
this.country = country;
this.street = street;
this.state = state;
this.zip = zip;
}
public String getCity()
{
return city;
}
public String getCountry()
{
return country;
}
public String getStreet()
{
return street;
}
public String getState()
{
return state;
}
public int getZip()
{
return zip;
}
#Override
public String toString()
{
StringBuilder builder = new StringBuilder();
builder.append("AddressImpl [city=");
builder.append(city);
builder.append(", country=");
builder.append(country);
builder.append(", state=");
builder.append(state);
builder.append(", street=");
builder.append(street);
builder.append(", zip=");
builder.append(zip);
builder.append("]");
return builder.toString();
}
}
The issue appears to be with Address. I get this exception:
Exception in thread "main" org.codehaus.jackson.map.JsonMappingException: Can not construct instance of com.art.starter.jackson_starter.Address, problem: abstract types can only be instantiated with additional type information
at [Source: java.io.StringReader#785f8172; line: 1, column: 2]
at org.codehaus.jackson.map.JsonMappingException.from(JsonMappingException.java:163)
at org.codehaus.jackson.map.deser.StdDeserializationContext.instantiationException(StdDeserializationContext.java:212)
at org.codehaus.jackson.map.deser.AbstractDeserializer.deserialize(AbstractDeserializer.java:97)
at org.codehaus.jackson.map.deser.SettableBeanProperty.deserialize(SettableBeanProperty.java:230)
at org.codehaus.jackson.map.deser.BeanDeserializer._deserializeUsingPropertyBased(BeanDeserializer.java:595)
at org.codehaus.jackson.map.deser.BeanDeserializer.deserializeFromObject(BeanDeserializer.java:472)
at org.codehaus.jackson.map.deser.BeanDeserializer.deserialize(BeanDeserializer.java:350)
at org.codehaus.jackson.map.ObjectMapper._readMapAndClose(ObjectMapper.java:2391)
at org.codehaus.jackson.map.ObjectMapper.readValue(ObjectMapper.java:1614)
at com.art.starter.jackson_starter.App.main(App.java:56)
I am sure this is because there is no way for Jackson to resolve Address which is an interface to AddressImpl which is a concrete implementation. I have been poking through the docs and have looked at a few articles regarding the #JsonDeserialize(as=AddressImpl.class),but it didn't work. So I am stumped. Has anyone ever gotten this to work, is it even supported?
It works like a champ if I replace Address with AddressImpl in the UserImpl class.

Just in case you hadn't seen it, here's a blog entry that discusses working with immutable objects and Jackson.
But you should definitely be able to use #JsonDeserialize(as=AddressImpl.class); either by adding it to Address.java interface (either directly or by using mix-ins), or by adding it to field or property. One thing to note is that for deserialization, it MUST be next to accessor you use; setter if you have one, if not, next to field. Annotations are not (yet) shared between accessors; so for example adding it to 'getter' would not work.
Jackson 1.8 also finally allows registration of abstract-to-concrete types (see http://jira.codehaus.org/browse/JACKSON-464 for more details) which might be the best option to indicate that 'AddressImpl' is to be used for 'Address'.