I have a enum in which I need to set the country in the web page.
Similar to this page - Java enum elements with spaces?
// sample
INDIA("India"),
RUSSIA("Russia"),
NORTH_AMERICA("North America");
I want the user to see "North America" in the dropdown.
But I need to pass "NA" to the database.
I tried the following. But getting the shortcode(IND,RUS,NA) in the dropdown.
IND("India"),
RUS("Russia"),
NA("North America");
Can anyone please help me in fixing this?
You can have an enum like this, where you use the name when displaying it in dropdown and the code, when passing to the DB.
enum Country {
INDIA("India", "IND"), RUSSIA("Russia", "RUS"), NORTH_AMERICA(
"North America", "NA");
private String name;
private String code;
Country(String name, String code) {
this.name = name;
this.code = code;
}
// Getters and other methods for name and code
}
you should try with variables inside the enum.
So your enum should be like this
public enum Country {
INDIA("India","IND"),
RUSSIA("Russia","RUS"),
NORTH_AMERICA("North America","NA");
private String country;
private String shortCode;
private Country(String country, String shortCode) {
this.country = country;
this.shortCode = shortCode;
}
public String getCountry() {
return country;
}
public String getShortCode() {
return shortCode;
}
}
Related
In my Android project I have two types of response where both response are identical except two keys.
Response 1
{"fullName":"William Sherlock Scott Holmes","address":"221B Baker Street, London, England, UK","downloads":642,"rating":3,"repos":["https://link1","https://link2","https://link3"]}
Response 2
{"name":"Sherlock","city":"London","downloads":642,"rating":3,"repos":["https://link1","https://link2","https://link3"]}
If you see the responses only two key names are changing fullName/name and address/city
I don't want to create one more pojo for other response. My question is: is it possible to use only one Pojo to read both responses?
public class AccountInfo {
private String name;
private String city;
//other objects
public String getName() {
return name;
}
public void setName(String name) {
this.name = name;
}
public String getCity() {
return city;
}
public void setCity(String city) {
this.city = city;
}
//other setters and getters
}
Any help will be appreciated...
You can annotate the members to accept values from two different json names using the #SerializedName annotation:
#SerializedName(value = "name", alternate = {"fullName"})
private String name;
#SerializedName(value = "city", alternate = {"address"})
private String city;
Either named element can then be placed into the members that are annotated like this.
UPDATED :
#SerializedName alternate names when deserializing is added in Version 2.4
Yes, you can totally use one POJO class for deserializing both responses. Your POJO class will contain keys from both responses.
public class Response {
private String name;
private String city;
private String fullName;
private String address;
private Integer downloads;
private Integer rating;
private List<String> repos ;
}
But when using the Response class, be careful that for first response, the name and city will be null, and for the second one, the address and fullname.
Yeah you can do that in a single POJO. Try this:
public class POJO {
#SerializedName("name")
public String name;
#SerializedName("city")
public String city;
#SerializedName("fullName")
public String fullName;
#SerializedName("address")
public String address;
#SerializedName("downloads")
public Integer downloads;
#SerializedName("rating")
public Integer rating;
#SerializedName("repos")
public List<String> repos = new ArrayList<String>();
}
While parsing you have to check values for null. For eg -
While Parsing Response 1: name and city variables will be null
While Parsing Response 2: fullname and address will be null
Note : Try checking values for null before using else you'll get nullpointerexception
Define all possible fields in your POJO Class like
public class AccountInfo {
private String name;
private String city;
private String fullname;
private String address;
}
While performing operation check for null in those feilds
I'm trying to learn about serialization and encountered the following problem:
I have an implementation of a customer that looks somewhat like this.
private static customerCount = 0;
private String customerID;
private String name;
private String street;
private String city;
private String postcode;
private String type;
I'm trying to serialize / deserialize an Arraylist
In the constructor, the ID will be created like this:
private Customer(...){
this.customerID = "ID" + customerCount;
customerCount++;
}
The serialization process works, however, all the IDs are set to ID0 when I deserialize.
Can anyone help resolve this problem?
Update: Alright, I just found out that static fields wont be serialized. How can I "model" the ID of a customer so I can serialize it? I need to have a unique value to create IDs for customers.
Here's a solution that combines the factory with the list that keeps track of customer count.
The customer class has a protected constructor, forcing you to build them through another means within the same package.
public class Customer implements Serializable {
private String customerID;
private String name;
private String street;
private String city;
private String postcode;
private String type;
protected Customer(String customerID,
String name,
String street,
String city,
String postcode,
String type) {
this.customerID = customerID;
this.name = name;
this.street = street;
this.city = city;
this.postcode = postcode;
this.type = type;
}
}
Now within the package, create a list wrapper like this:
public class CustomerList {
private int customerCount = 0;
private List<Customer> customers = new ArrayList<>();
public boolean addCustomer(String name,
String street,
String city,
String postcode,
String type) {
Customer customer = new Customer("ID" + customerCount++,
name,
street,
city,
postcode,
type);
return customers.add(customer);
}
}
This class then takes care of constructing the new customer, and provides a unique ID.
Edit: Just noticed that you now also have the upside of making the CustomerList class serializable as well. Then you can load it and still have an accurate customer count for adding additional uniquely ID-ed customers.
Usually, you would like to serialize only attributes and their values, not the logic from the class. Logic should happen before serialization or after deserialization.
Evening,
I retrieve JSON data from a server in this format:
Json-Book:
{
_id: String,
isbn: String,
owner: String username,
rentedTo: Array[String usernames]
}
Json-Crowd:
{
_id: String,
isbn: String,
owner: String username,
availableForRent: Integer,
rentedTo: Array[String usernames]
}
Json-User:
{
username: String,
books: Array[Book],
crowds: Array[Crowd]
}
Similarly, I have three classes:
public class Book{
private String _id;
private String isbn;
private User owner;
private ArrayList<User> rentedTo;
public Book(String _id, String isbn, User owner, ArrayList<User> rentedTo) {
this._id = _id;
this.isbn = isbn;
this.owner = owner;
this.rentedTo = rentedTo;
}
}
public class Crowd {
private String _id;
private String name;
private User owner;
private ArrayList<User> members;
public Crowd(String _id, String name, User owner, ArrayList<User> members) {
this._id = _id;
this.name = name;
this.owner = owner;
this.members = members;
}
}
public class User {
private String name;
private Shelf shelf;
private ArrayList<Book> books;
private ArrayList<Crowd> crowds;
public User(String name, ArrayList<Book> books, ArrayList<Crowd> crowds) {
this.name = name;
this.booksOwned = books;
this.crowds = crowds;
}
}
As you can see, all the field names match up, but not all of the types. Users in the keys owner and rentedTo in Json-book and Json-crowd have values of type String and ArrayList<String> respectively, where the strings are unique usernames. In the classes, these fields are of type User and ArrayList<User>. In and of itself, this is no problem, because I can get the User object from the string with this method:
public User getUser(String username) {
return users.get(username);
}
Now, I'm a bit confused as to what deserializers I need in order to get proper objects from the JSON data. How would the, uh, architecture of this look? Deserializers for each class Book, Crowd and User, each of which fetches one field at a time from the Json-data and calls the constructor?
I can't wrap my head around how this would work together. The deserializer for User would need to use/reference the deserializer for Crowd, but do I another deserializer since the objects are in array?
I assume I would need an opposite set of serializers in order to get the classes into Json-data of the correct format.
I have some old code which is working fine but now i want to use #JsonCreator in domain objects and i am able to re-factor all stuff but i am now stucked in one issue. In one scenario i have Json Structure like:
[{
"name" : "John",
"emailAddress" :"stucked#gmail.com"
}]
But in java backend i have structure like:
class Employee {
public final String name;
public final EmailAddress emailAddress;
Employee(final String name, final EmailAddress emailAddress) {
this.name = name;
this.emailAddress = emailAddress;
}
Employee() {
this(null, null)
}
}
class EmailAddress {
public final String address;
EmailAddress(final String address) {
this.address = address;
}
EmailAddress() {
this(null);
}
}
So I am trying like :
class Employee {
public final String name;
public final EmailAddress emailAddress;
#JsonCreator
Employee(#JsonProperty("name")final String name,
#JsonProperty("emailAddress")final EmailAddress emailAddress) {
this.name = name;
this.emailAddress = emailAddress;
}
}
class EmailAddress {
public final String address;
#JsonCreator
EmailAddress(#JsonProperty("address")final String address) {
this.address = address;
}
}
Now the problem is in using #JsonProperty with "emailAddress" field in Employee domain object and then #JsonProperty inside EmailAddress Object with "address" because in Json i dont have any "address" property and due to which JsonParsing error is coming.
Well problem can be easily solved if i declare emailAddress as String instead of EmailAddress and remove EmailAddress object but address field of EmailAddress object is used at many other places, modification of which require lot of effort and there are lots of such cases. Is there any other solution??
So what exactly is your problem here? If the goal is to allow both of these:
"stucked#gmail.com"
{ "address" : "stucked#gmail.com" }
it should already work: Jackson figures out that single-String constructor may be used if JSON String is found; and setters/fields if a JSON Object is found. You just need to ensure names match ("address" vs "emailAddress").
You want to create a program for the management of a telephone book.
For each person are provided for the following personal information:
Surname
Name
Title
E-mail address (can not contain spaces and must contain the # symbol)
Company
Position
For every person you can store the following telephone numbers (one for each category)
Home
Office
Mobile Phone.
You can also store a list of other phone numbers. For each of the other numbers, you must store over to the phone number
a description of the number.
Here it is a homework I have to make for this evening in Java.
My issue is how I can implement the various category: Home,Office,ecc...Which is the best solution to implement those category? maybe an enum?
Here it is my implementation:
import java.util.*;
public class Persona {
private String Name;
private String surname;
private String title;
private String mail_addr;
private String company
private String position;
private Phone homePhone;
private Phone officePhone;
private Phone mobilePhone;
private Collection<Phone> otherphonesList
public Persona(String n,String s,String t,String m,String c,String p,Phone hp,Phone of,Phone mp,Collection<Phone> otherphones)
{
name=n;
surname=s;
title=t;
mail_addr=m;
company=c;
position=p;
homePhone=hp;
officePhone=of;
mobilePhone=mp;
otherphonesList=new ArrayList<Phone>(otherphones);
}
public String getName()
{
return name;
}
public String getSurname()
{
return surname;
}
public String getTitle()
{
return title;
}
public String getMail()
{
return mail_addr;
}
public String getCompany()
{
return company;
}
public String getPosition()
{
return position;
}
}
public class Phone {
private String phone;
private String description;
public Phone(String phone,String description)
{
this.phone=phone;
this.description=description;
}
public String getPhone()
{
return phone;
}
public String getDescription()
{
return description;
}
}
You can write a PhoneBook class with fields you need:
public class PhoneBook {
private Phone homePhone;
private Phone officePhone;
private Phone mobilePhone;
private List<Phone> otherPhones;
..getters/setters..
}
public class Phone {
private String phone;
private String description;
..getters/setters..
}
enums are a good solution if:
The number of items is fixed
All the information of the item is fixed as well (no loading of external files/resources/etc).
In a real application, you probably need to display the category on a display. This includes translating the category into the user's language which means there is an external dependency.
In such a case, you would use the enum as a key for a factory that gives you the text for each entry in the enum. The factory decouples your constant enum from the variables in the real world (like different/changing translations in the UI).
You may have a look at the Map class to store the phone numbers and add accessors for home, office and mobile phone entries.