Java supports generic types and methods. Why not generic fields? -

-

Despite the fact that janetics [Java Runtime] is not in Java, I was recently caught in some kind of generic Hell is there

Status (simplified and useless reference removed):

A library is A, which provides interface IA. A library is B, which provides interface IB. Both libraries are third party libraries on which I do not have any control. (In reality, there are more than 2 but they are not so complex yet.)

An engine developed by my company , Which defines both objects and heavily uses / implementing both IA and IB Since our engine should deal with all implementations, we should only implement some interface IAB, IB Can not define and allow all sections to be implemented. Therefore, to get the collection time, type-security & amp; Method risk, it was decided to use normal methods. Therefore, whenever an 'IAB' is required, we will be able to & lt; IAB IA & amp; IB & gt; Do this with zero (IAB some object withboth API) .

It works very well, though in fact as a fact, & lt; It is not possible to do something simple as IAB IA IA & amp; IB & gt; IAB FieldwithbothAPIS; (Neither the the IA and the IB fields with the APIs ). Which tells us about the question:

Why not?

Actually, (design-level?) Arbitrary typeparams (opt) , while example field concrete type ?

JLS §8.3 

  fieldDocumentation: Field Modifiers (opt) type variableDeveloper;

JLS §8.4 )

A common method receives logic from its charge context on runtime, thus it can obtain different types in different circumstances.

How will a common field type argument get? In some contexts, there can be no different type of field depending on its usage, it should be a single type, which is known on time.


Comments

Post a Comment

Popular posts from this blog

java - org.apache.http.ProtocolException: Target host is not specified -

-
I have written a simple httprequest / response code and I am getting this error below: I used to type in my classpath httpclient, httpcore, common -Codecs and general logging. I am very new to Java and I do not know what's going on here. Please help me. code: import org.apache.http.client.HttpClient; Import org.apache.http.client.methods.HttpGet; Import org.apache.http.HttpResponse; Import org.apache.http.impl.client.HttpClientBuilder; Import org.apache.http.Header; Import org.apache.http.HttpHeaders; Public class UnshorteningUrl {public static zero main (string [] args throws exception {HttpGet request = zero; HTTP Client Client = HTTP ClientBuilder.credit (). Build (); Try {Request = New HTTP Gate ("trib.me/1lBFzSi"); HttpResponse httpResponse = client.execute (request); Header [] header = httpResponse.getHeaders (HttpHeaders.LOCATION); // Preconditions.checkState (headers.length == 1); String new url = header [0] .getValue (); System.out.println ("new url...
Read more

java - Gradle dependencies: compile project by relative path -

-
Is it possible to specify a dependency on another gradeal project in the granular (in android studios) outside the current project limits? For example, with a relative path like this: dependence {collection project ('../../ stdlib / dagger'}} MyApp (path / user / foo / workspace / mypad) The app (Path / User / Foo / Workspace / MyPass / App) And I have an Android Library Project with 3 subdomules: stdlib (path is / user / foo / Utilities (Path / User / Foo / Workspace / Stadlib / Utilis) http (Path / User / Foo / Workspace / Stadlib / HT) / Li> What I have to do is compile the Dagger, Util, http module in the MyApp project. The Stidelib Library module under heavy development And MyApp will grow in the form of Growth, so I do not want to push them into a Mewen repository. I am a little change. is likely to add another Gredle projects in some way? I will push the study library into the Maven repository after the source is in search of a temp...
Read more

ruby on rails - Object doesn't support #inspect when used with .include -

-
So I have participated in a glitch error that I do not even know how to debug. I am very new to the railing, so it has kicked my ass well when I use the .includes (school) seen by the student, it gives a blue box error, But when I look at any other model and .includes (school) , the school works just fine. class student & lt; ActiveRecord :: Base has has_many: relationships, foreign_key: "liker_id", dependent :: has_many: matches, foreign_key: "student_1_id", dependent :: deleted belong_to: school belong_to: conference belong_to: would_you_rather belong_to: home city belong_to: year is_to: Major and class school & lt; on the console activatecord :: Affiliate for the base: conference includes: respondent, class: "school", foreign_key: "rival_id" (e.g. For: School) Select SQL generated Select "School". * "School" from "school" "ID" IN (1) error message back NoMethodError: u...
Read more