interface

问题 I have an interface for a variety of classes, all of which should implement Iterator, so I have something like public interface A extends Iterable<A> { ...otherMethods()... } For the concrete classes, however, this means I must use public class B implements A { public Iterator<A> iterator() {...} } when I'd prefer (or at least, think I'd prefer) to use public Iterator<B> iterator() {...} so that concrete use of the class could have the explicit type (in case I wanted methods that weren't in

问题 I have created Singleton class for SocketIOClient reference by here. Server was connected. I can able to send request from activity to SocketIOClient. But how can I get response from Singleton class in Activity? Here My Activity: import java.net.MalformedURLException; import org.json.JSONException; import org.json.JSONObject; import android.app.Activity; import android.os.Bundle; import android.view.Menu; import android.view.View; import android.view.View.OnClickListener; import android

问题 Is it possible for multiple wcf services to implement the same service contract interface? What I want to do is allow for a test service to be interchangeable for the real service, and to specify which service to be used in the configuration file. For example: [ServiceContract] public interface IUselessService { [OperationContract] string GetData(int value); } Test implementation public class TestService : IUselessService { public string GetData(int value) { return "This is a test"; } } Real

问题 I'd like to make an icon for my NSToolbar that has the same system stylings applied to it as the template icons in IB. How do you do this? I can't get the toolbar to apply system stylings like it says it will in the HIG. Thanks! 回答1: If you mean for a monochromatic icon, make sure you set it as a template image. That's what tells the system to render it with the inner gray or blue gradient. 回答2: In Mac OS X v10.5 or later, images whose name ends in the word "Template" are automatically marked

问题 The normal way to create a videocapture is this: cam = cv2.VideoCapture(n) where n corresponds to the number of /dev/video0 , dev/video1 But because I'm building a robot that uses multiple cameras for different things, I needed to make sure that it was being assigned to the correct camera, I created udev rules that created devices with symbolic links to the correct port whenever a specific camera was plugged in. They appear to be working because when I look in the /dev directory I can see the

问题 I would like to understand the following type of syntax. Example: public interface A < T extends A < T> > { } What is the logic of this interface ? 回答1: This would be used as follows: class X implements A<X> { /* ... */ } In other words, you are forced to make the parameter of A the class X itself, and something like class X implements A<Unrelated> is forbidden. This construction gives the interface access to X through the generic parameter, and the type restriction makes sure that it doesn't

问题 This question already has answers here : Are defaults in JDK 8 a form of multiple inheritance in Java? (9 answers) Virtual Extension Methods in upcoming Java 8 release (5 answers) Closed 6 years ago . During a discussion one of my friend tell me that concrete methods would be allowed in java 1.8 in interfaces then at that time a question came into my mind i-e If they are allowed then How will we distinguish the methods.For example I have two Interface Animal.java and Pet.java and both have

问题 As it currently stands, this question is not a good fit for our Q&A format. We expect answers to be supported by facts, references, or expertise, but this question will likely solicit debate, arguments, polling, or extended discussion. If you feel that this question can be improved and possibly reopened, visit the help center for guidance. Closed 7 years ago . I know and understand the value of interfaces in Java. You code to the interface, and then you can change your implementations without

问题 If we have: public interface Foo{} public class Bar implements Foo{...} Is there a difference between: public class BarBar extends Bar implements Foo{..} and public class BarBar extends Bar{..} I see a lot of code like this and it always confuses me. Does BarBar need to implement Foo ? I mean since it extends Bar to begin with isn't that already there? I guess my question is, what purpose does implementing Foo in BarBar serve here? 回答1: The main difference is 15 completely unnecessary

问题 How to implement an abstract class in Go? As Go doesn't allow us to have fields in interfaces, that would be a stateless object. So, in other words, is it possible to have some kind of default implementation for a method in Go? Consider an example: type Daemon interface { start(time.Duration) doWork() } func (daemon *Daemon) start(duration time.Duration) { ticker := time.NewTicker(duration) // this will call daemon.doWork() periodically go func() { for { <- ticker.C daemon.doWork() } }() }