CODEWITHSUNDEEP
java
Vlad Shevchenko
Vlad Shevchenko

Reputation: 768

Easy way to fill object's fields

I have many servlets like this:

public class DoSmthServlet extends AbstractDTOServlet<DoSmthServlet.Params> {

    @Override
    public Response service(Params params) throws Exception {
        // Some logic...

        Response response = new Response();
        response.field1 = data1;
        response.field2 = data2;
        // ...
        return response;
    }

    public static class Params implements DomainDTO {
        public long arg1;
        public boolean arg2;
        // ...
    }

    public static class Response implements DomainDTO {
        public String field1;
        public long field2;
        // ...
    }

}

I need to fill Response object with data, but it can contain really many fields. How to do it without writing many response.fieldN = dataN in each servlet? I don't want to write constructors for each class because I'll still have to write such assignments in constructors.

Maybe there is any library that can do it, or any pattern that I can use, or any way to generate constructors for Response classes?

Upvotes: 1

Views: 1295

Answers (3)

NightWatcher
NightWatcher

Reputation: 148

If number of fields are same for all the Response object then write one static function and call it from different servlets. static function will do all response.fieldN = dataN

Upvotes: 0

Arek
Arek

Reputation: 3176

I don't know any library that can do it for you. But... you can use fluent builder which will simplify Response creation and make it a little bit... easier I think.

ex.

public class ResponseBuilder {
   private Response response = new Response();
   public ResponseBuilder withField1(String field1) {
      response.field1 = field1;
      return this;
   }
   public ResponseBuilder withField2(String field2) {
      response.field2 = field2;
      return this;
   }
   public Response build() {
      return response;
   }
}

// usage
Response response = Response.builder.withField1("a").withField2("b").build();

BTW: I would rather avoid writing constructor with many arguments for a Value Object/DTO class, because every argument passed to constructor should be considered as required.

Upvotes: 0

skozlov
skozlov

Reputation: 414

Maybe Dozer bean mapper can help you. Some example:

Mapper mapper = new DozerBeanMapper();

DestinationObject destObject = 
mapper.map(sourceObject, DestinationObject.class);

or

DestinationObject destObject = new DestinationObject();
mapper.map(sourceObject, destObject);

Upvotes: 1

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