I'm working on an Android project and I'm trying to make use of an ArrayList which is of type MyClass. I am trying to store data in the ArrayList to each of the variables within MyClass. Below is the code I am using.
Below is the Class with the variables that will be used.
class SearchData
{
public int id;
public String category;
public String company;
public String loginAction;
public String username;
public String password;
public String type;
public String appName;
}
Below is how I am initialising the ArrayList
ArrayList<SearchData> passwords = new ArrayList<SearchData>();
And below is how I am trying to add new data to the ArrayList
passwords.add(new SearchData()
{
});
I can't figure out how to then set the variables from within the class with the data that I need them to be set to. In C#, which I know more about than Java, I can do the following:
passwords.add(new SearchData()
{
id = 0,
category = "hello"
});
However, I'm not seeing any of the variables that are within the class being shown in the Intellisense help.
What am I doing wrong?
You need to create an object and set all the attributes first, and then add it to the List: -
SearchData searchData = new SearchData();
searchData.setId(1);
searchData.setCategory(category);
...
passwords.add(searchData);
Create a constructor for your class.
class SearchData
{
public int id;
public String category;
public String company;
public String loginAction;
public String username;
public String password;
public String type;
public String appName;
SearchData(int id, String category, String company......){
this.id = id;
this.category = category;
this.company = company;
...
}
}
Then use it like this:
passwords.add(new SearchData(0,"Category1", "Company1"......));
Create an object and store reference to it:
SeachData searchData = new SearchData();
Set the properties you want to set:
searchData.setId(123);
...so on
searchData. Ctrl+Space should show the intellisense now..
Adding the search reference to the list:
list.add(searchData);
SearchData sd = new SearchData();
sd.id = 0;
sd.category = "hello";
passwords.add(sd);
Related
I am struggling to map a string object from source(Relation.class) and to a List of target(RelationListDTO.class) .
Relation.java
public class Relation {
private String name;
private String email;
private String completeAddress;
// getters and setters
}
RelationListDTO.java
public class RelationListDTO {
private String name;
private String email;
private List<Address> address;
// getters and setters
}
Address.java
public class Address{
private String street;
private String city;
// getters and setters
}
Mapper class
#Mapper
public interface RelationMapper {
#Mapping(source = "completeAddress", target = "address.get(0).city")
RelationListDTO relationToListDto(Relation relation);
}
But it is not working. Could anyone please help.
What you are trying to do using MapStruct is not possible. Because MapStruct doesn't work with run time objects. MapStruct only generated plain java code for mapping two beans. And I find your requirement is little unique. You have a list of Addresses but want to map only city from source object? You can still do like this
#Mapping( target = "address", source = "completeAddress")
RelationListDTO relationToListDto(Relation relation);
// MapStruct will know to use this method to map between a `String` and `List<Address>`
default List<Address> mapAddress(String relation){
//create new arraylist
// create new AddressObject and set completeAddress to address.city
// add that to list and return list
}
Not sure if this was possible at the time of the accepted answer but I had the same problem as you and ended up doing it this way.
#Mapper(imports = Collections.class)
public interface RelationMapper {
#Mapping(expression = "java(Collections.singletonList(relation.getCompleteAddress()))", target = "address")
RelationListDTO relationToListDto(Relation relation);
}
I have an object extending SugarRecord that looks like this:
public class SavedDraft extends SugarRecord {
private String name;
private String difficulty;
private int sport_id;
private LocalActivity localActivity;
public SavedDraft() {
}
public SavedDraft(String name, String difficulty, int ID, LocalActivity localActivity) {
this.name = name;
this.difficulty = difficulty;
this.sport_id = ID;
this.localActivity = localActivity;
}
}
The problem is that I always get a null object when I try to get the localActivity object from the database (see: SavedDraft.findById(SavedDraft.class, 1).getLocalActivity()), and I'm just wondering if it's possible to save objects as parameters in SugarORM at all.
This would be a relationship and you would need the LocalActivity to extend SugarRecord also.
See the documentation of Book and Author: http://satyan.github.io/sugar/creation.html
I'm currently working on this code, I want to pass an ID to a member function to get the object.
public class Car {
private int _ID;
private String name;
private String model;
Car(int _id, String name, String model){
this._ID = _id;
this.name = name;
this.model = model;
}
....
public static Car getCar(int _id){
Car mCar;
//TODO: Algo to get car
return mCar;
}
}
Is there any way I can get the object in this way?
Any help is appreciated!
Thank You!
You'll need to keep a Map of objects by key. Here's one way to do it:
public class Car {
private int _ID;
private String name;
private String model;
Car(int _id, String name, String model){
this._ID = _id;
this.name = name;
this.model = model;
carsById.put(_id, this); // <-- add to map
}
....
private static Map<Integer, Car> carsById = new HashMap<>();
public static Car getCar(int _id){
return carsById.get(_id);
}
}
There's no predefined way to do that. You'd have to have Car or something else maintain a Map<Integer,Car> or similar of cars. This would usually be best done not in Car itself, but in the code using it.
Unless you have a list (or map or tree or anything else suitable) of created Car, it's not possible with your current code only. A good practice is to separate this list out of Car class, maintained elsewhere. But if you insist, shmosel provides one way.
What design-pattern, if any, would be most appropriate in this situation.
public class PersonFromDB1 {
private String firstName;
private String lastName;
private String Car;
}
public class PersonFromDB2 {
private String first_name;
private String last_name;
private String boat;
}
Out of these two person types, the only data I would like to work on is fist name and last name regardless of how it field name is name inside the different DBs. firstName and first_name represents the same - name of a person/customer - so does lastName and last-name. The car and boat fields are, in my example, completely irrelevant and should therefore be ignored.
Using, maybe polymorphism or the adapter pattern (?), I would like to create a list of objects that includes persons from DB1 and DB2 under the same type - of PersonInOurDB.
In the end, my goal is to be able to call GSON serialization/desarialization on myClass alone.
public class PersonInOurDB {
private String firstname;
private String lastname;
}
A simple selection based on the type is all you really need. This could be considered a builder pattern because it just initializes a new instance of myClass.
Note, this is rough pseudo code.
FunctionName(SomeType instance)
{
string aPostfix = "_1";
string bPostfix = "_2";
string selectedPostFix;
// This is your strategy selector
switch(typeof(SomeType.Name)
{
case "TypeA":
selectedPostFix = aPostFix;
case "TypeB":
selectedPostFix = bPostFix;
}
return new myClass()
{
A = instance.GetProperty("A" + selectedPostfix).Value,
B = instance.GetProperty("B" + selectedPostfix).Value,
...
}
}
If you want a common access api in java for both objects, then introduce an interface and let both implement it.
If you only want both objects (PersonFromDB1 and PersonFromDB2) to be serialized in the same way by json you can either:
use annotations - the #SerializedName annotation in combination with #Expose.
use the FieldNamingStratgy and ExclusionStrategy
Use annotations to control the serialization
public class PersonFromDB1 {
#Expose
#SerializedName("firstName")
private String firstName;
#Expose
#SerializedName("lastName")
private String lastName;
private String car;
}
public class PersonFromDB2 {
#Expose
#SerializedName("firstName")
private String first_Name;
#Expose
#SerializedName("lastName")
private String last_Name;
private String boat;
}
Then you can use the GsonBuilder
Gson gson = new GsonBuilder().excludeFieldsWithoutExposeAnnotation().create();
PersonFromDB1 person1 = ...; // get the object
PersonFromDB2 person2 = ...; // get the object
System.out.println(gson.toJson(person1));
System.out.println(gson.toJson(person2));
Use FieldNamingStratgy and ExclusionStrategy to control the serialization
If you don't want to modify the db objects (you can't or you don't want to add annotations) than there is another way. You can use a FieldNamingStratgy and ExclusionStrategy.
class PersonFromDBNamingStrategy implements FieldNamingStrategy {
Map<String, String> fieldMapping = new HashMap<String, String>();
public PersonFromDBNamingStrategy() {
fieldMapping.put("first_Name", "firstName");
fieldMapping.put("last_Name", "lastName");
}
#Override
public String translateName(Field f) {
String name = f.getName();
if(fieldMapping.contains(name)){
return fieldMapping.get(name);
}
return name;
}
}
and the ExclusionStrategy
class PersonFromDExclusionStrategy implements ExclusionStrategy {
List<String> validNames = Arrays.asList("car", "boat");
#Override
public boolean shouldSkipField(FieldAttributes f) {
String name = f.getName();
return !validNames.contains(name);
}
#Override
public boolean shouldSkipClass(Class<?> clazz) {
return false;
}
}
after that just create Gson like this:
GsonBuilder gsonBuilder = new GsonBuilder();
sonBuilder.addSerializationExclusionStrategy(new PersonFromDExclusionStrategy());
gsonBuilder.setFieldNamingStrategy(new PersonFromDBNamingStrategy());
Gson gson = gsonBuilder.create();
PersonFromDB1 person1 = ...; // get the object
PersonFromDB2 person2 = ...; // get the object
System.out.println(gson.toJson(person1));
System.out.println(gson.toJson(person2));
after messing around with parsing a JSON response with GSON for a day, I finally figured out how to get my javabeans right in order to extract my data from the response. This is the layout of my nested classes and lists:
public class LocationContainer {
public class paging {
private String previous;
private String next;
}
private List<Datas> data;
public class Datas {
private String message;
private String id;
private String created_time;
public class Tags {
private List<Data> datas;
public class Data {
private String id;
private String name;
}
}
public class Application {
private String id;
private String name;
}
public class From {
private String id;
private String name;
}
public class Place {
private String id;
private String name;
public class Location {
private int longitude;
private int latitude;
}
}
}
}
Now I am trying to get a hold of the name string inside the place class and the created_time string, but since I am quite a noob, I can't seem to figure it out.
I was able to extract the created_time string by using
String time = gson.toJson(item.data.get(1).created_time);
However using
String name = gson.toJson(item.data.get(1).Place.name);
doesnt work.
The item class is an instance of LocationContainer filled with the output from GSON.
Any pointers would be greatly appreciated.
created_time is a member variable of Data, so your first line is fine.
However, Place is not a member variable, it's just a class definition. You probably need to instantiate a member variable inside your Data class, e.g.:
private Place place;