interface

问题 what is the concept of set variable or object or i don't know what it's called when i create instance of class and putting in left hand the name of interface,,, I Know that we can't create and object of type interface. Only I need more clarification what this process named or what is the details done by .Net when I declare these type of object. IDataReader oSQLReader = new SqlDataReader(); IDataReader oOLEReader = new OleDbDataReader(); 回答1: What happens exactly is that you are creating an

问题 In kubectl/run.go in Kubernetes code, the Generate function has a result list of these two types: runtime.Object, error The last line of the function is: return &deployment, nil runtime is imported: k8s.io/apimachinery/pkg/runtime I got runtime by running go get on that import statement, and Object is defined in interfaces.go : type Object interface { GetObjectKind() schema.ObjectKind DeepCopyObject() Object } (And I found the same code on the web here.) The address operator creates a pointer

问题 I am a little bit familiar with the difference between Abstract and Interface classes but What do you think is the meaning of the sentence below? An interface can only define constants while abstract class can have fields. 回答1: An interface can only define constants while abstract class can have fields. your field from interface is by implicitly public , static , final which isn't case with abstract class 回答2: constants - static, not changing ( static final ) fields - instance-specific,

问题 I wish to know when we can use an interface extending another interface. I wish to know a practical example and when we use it. 回答1: You extend an interface when a subinterface provides everything the superinterface provides, and does something else of importance. For example, SortedMap<K,V> implements Map<K,V> , because sorted map is a map that supports all operations of a map, plus some operations applicable only to sorted maps. This is similar to inheriting among classes, but it allows for

问题 There are a lot of questions floating around with this problem and i've worked through them ll with no joy. I am receiving this error: Method 'get_UserImageCDNUrl' in type 'App.Web.WebConfig' from assembly 'App.Web, Version=1.0.0.0, Culture=neutral, PublicKeyToken=null' does not have an implementation. Which is really strange because I am trying to run Api.Web which has no reference to App.Web, the only thing they have in common are references to other projects (Models.Domain and Models.DTO).

问题 The java compiler allows me write a Class definition inside an Interface . Are there any specific uses of this ? interface ClassInterface { void returnSomething(); int x = 10; class SomeClass { private int y; private void classDoingSomething() { } } } Please explain . 回答1: You would use it to tightly bind a certain type to an interface. Read This page for further information and an example of defining a class inside an interface. 回答2: The uses are the same that a class nested in another class

问题 The java compiler allows me write a Class definition inside an Interface . Are there any specific uses of this ? interface ClassInterface { void returnSomething(); int x = 10; class SomeClass { private int y; private void classDoingSomething() { } } } Please explain . 回答1: You would use it to tightly bind a certain type to an interface. Read This page for further information and an example of defining a class inside an interface. 回答2: The uses are the same that a class nested in another class

问题 ImmutableSet implements the Set interface. The functions that don't make sense to an ImmutableSet are now called "Optional Operations" for Set . I assume for situations like this. So ImmutableSet now throws an UnsupportedOperationException for many Optional Operations. This seems backwards to me. I was taught that an Interface was a contract so that you could use impose functionality across different implementations. The approach of Optional Operations seem to fundamentally change(contradict?

问题 I have to design an interface for hierarchical entity: interface HierarchicalEntity<T extends HierarchicalEntity<T>> { T getParent(); Stream<T> getAncestors(); } It's quite easy to implement default getAncestors() method in terms of getParent() in such a way that the former would return Stream of all the ancestors. Implementation example: default Stream<T> getAncestors() { Stream.Builder<T> parentsBuilder = Stream.builder(); T parent = getParent(); while (parent != null) { parentsBuilder.add

问题 I have to design an interface for hierarchical entity: interface HierarchicalEntity<T extends HierarchicalEntity<T>> { T getParent(); Stream<T> getAncestors(); } It's quite easy to implement default getAncestors() method in terms of getParent() in such a way that the former would return Stream of all the ancestors. Implementation example: default Stream<T> getAncestors() { Stream.Builder<T> parentsBuilder = Stream.builder(); T parent = getParent(); while (parent != null) { parentsBuilder.add