How to create a Java object which contains selected properties?

user_6658186 0
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Consider the following class.

public class UserDTO {


 private String email;
        private String password;
        private String country;
        private String fName;
        private String lName;
        private String type;
        private String profPicPath;

    public UserDTO(String fNme, String lNme, String profPic) {
        this.setfName(fNme);
        this.setlName(lNme);
        this.setProfPicPath(profPic);
    }

    public String getEmail() {
        return email;
    }

    public String getCountry() {
        return country;
    }

    public void setCountry(String country) {
        this.country = country;
    }

    public String getfName() {
        return fName;
    }

    public void setfName(String fName) {
        this.fName = fName;
    }

    public String getlName() {
        return lName;
    }

    public void setlName(String lName) {
        this.lName = lName;
    }

    public String getType() {
        return type;
    }

    public void setType(String type) {
        this.type = type;
    }

    public void setEmail(String email) {
       this.email = email;
    }

    public String getPassword() {
        return password;
    }

    public void setPassword(String password) {
        this.password = password;
    }

    public String getProfPicPath() {
        return profPicPath;
    }

    public void setProfPicPath(String profPicPath) {
       this.profPicPath = profPicPath;
    }

I want to create an object only contains the fName, Lname and profPicPath. I have created a constructor to initialize only these three fields. But when I create an object using this constructor it contains the other properties as well with null values. Is there any approach in Java to create an object only with a selected properties ?

object constructor oop java
2 Answers

I think you are confused between the domain/model object and DTO object. The domain/model class represents the full set of attributes while you specific DTOs representing subsets of attributes in the domain/model class e.g. the User class is your domain/model class representing the full set of attributes (email, password, country, fName, lName, type, gender, country, profPicPath etc.) and then you can have DTOs like, UserLoginCredentialDTO (with email and password attributes), UserDemographyDTO (with attributes like gender, country etc.).

You can also check https://softwareengineering.stackexchange.com/questions/155768/what-oo-design-to-use-is-there-a-design-pattern for another example.

Apart from this, the comments of JB Nizet and Abra are quite valid and will help you understand this concept better in terms of Java.

Admin1

yes. the approach is called inheritance. You need to create a BaseUserDTO that contains the subset of properties that is shared between the two entities. (they need to be declared as protected to be accessible to the subclass) UserDTO will extend the base class so it contains all its properties plus its own. the constructor with three properties must call the matching super constructor in order to initialize the shared properties

user_47909240
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