interface

问题 OnClickListener is an static interface but I am instantiating from OnClickListener. I'm confused and wondering that can we generate objects from interface in java? Why don't we create concrete class, inherit from OnClickListener interface? 回答1: That is what is known as an anonymous inner class . The Swing documentation for Java Standard Edition covers it here, and I imagine it's used for much the same purpose in Android development. It allows you to more simply hook up various event handler

问题 (Note: Question updated with full reproducible example) After migrating an F# project from VS 2012 to VS 2015 I receive an error on certain usages of interfaces. In particular it happens where a type implements two generic interfaces. I know this is not allowed in F# directly, but this type comes from C#. To reproduce the problem: 1. type definition in C#: Paste this in some class library. public interface Base { } public interface IPrime<T> : Base { T Value { get; } } public interface IFloat

问题 I have the following problem: I have interfaces IA in the ProjectA.dll and IB in the ProjectB.dll ( IB inherits IA ). When I try to implement IB in any another project the both references are required. Well, the requirement of a reference on the ProjectB.dll is expected, but I was little bit confused, that a reference on the ProjectA.dll is needed too. Does anybody know how is this feature called and where can I find detailed information about this behavior? 回答1: You'll need a reference to

问题 I have set up a project in Visual Studio to create a .dll. I have included an external library in the project which uses the keyword "interface". This is giving me the following error: error C2146: syntax error : missing ';' before identifier 'INuiAudioBeam' These are the lines of code where the error occurs: #ifndef __INuiAudioBeam_FWD_DEFINED__ #define __INuiAudioBeam_FWD_DEFINED__ typedef interface INuiAudioBeam INuiAudioBeam; //Error on this line #endif The above code is part of a header

问题 I'm currently doing a small personal project that needs to display an extremely large amount of data, and I suddenly thought about implementing a form of zoomable user interface to allow the user to navigate around the large amounts of data. I'm aware of existing projects such as ZVTM and Piccolo2d which I'll probably end up using for the job, however I'm also quite tempted to embark upon writing my own. However, I'm a little unsure as how to start. From what I've been reading, it seems that

问题 There are many predefined interfaces in java like ResultSet , Connection , Statement etc.An Interface can have only abstract methods (unimplemented methods).So why do we use there methods without defining them first. for example in following code of jdbc public class JDBCSample { public static void main( String args[]) { String connectionURL = "jdbc:postgresql://localhost:5432/movies; user=java;password=samples";` try { Class.forName("org.postgresql.Driver"); Connection con = DriverManager

问题 I think I understand the difference between interface and abstract. Abstract sets default behavior and in cases of pure abstract, behavior needs to be set by derived class. Interface is a take what you need without the overhead from a base class. So what is the advantage of interface over composition? The only advantage I can think is use of protected fields in the base class. What am I missing? 回答1: An interface defines how you will be used. You inherit in order to be reused. This means you

问题 While researching Android UI possibilities, I came across documentation for a method called addJavascriptInterface() that allows you to expose methods on an Android Java object to the Javascript in a WebView component of your UI. This idea seems so useful and obvious (in terms of concept, not implementation). However, I cannot seem to find any equivalent for a desktop version of the webkit engine. There are things out there like pywebkitgtk and qt's version of a webview that allow some

问题 In the OO world, I have a class (let's call it "Suggestor") that implement something approaching a "Strategy Pattern" to provide differing implementations of an algorithm at runtime. As an exercise in learning Haskell, I want to rewrite this. The actual use-case is quite complex, so I'll boil down a simpler example. Let's say I have a class Suggester that's takes a list of rules, and applies each rule as a filter to a list of database results. Each rule has three phases "Build Query", "Post

问题 If I have an interface: interface IMyInterface { void DoSomething(); } And an implementing class: class MyClass : IMyInterface { public void DoSomething() { } } Is DoSomething a candidate for inlining? I'd expect "no" because if it's an interface then the object may be cast as a IMyInterface, so the actual method being called is unknown. But then the fact that it's not marked as virtual implies it may not be on the vtable, so if the object is cast as MyClass, then maybe it could be inlined?