. NET Interface Learning Notes

Last Update:2016-08-11 Source: Internet

Author: User

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1. Declaration of the interfaceThe declaration of an interface cannot contain: a data member, a static variable, or a declaration of a static member function that can contain only the following types: methods, properties, events, indexers. The declaration cannot contain any implementation code, and a semicolon must be used after each member of the body that is famous.An interface declaration can have any modifier public, protect, internl, or Private.The members of the interface are implicitly public and do not allow any access modifiers, including Public.<pre><pre>1 public Interface IMyInterface 2 {3 // interface members are implicitly public, and only the declaration 4 int METHOD1 (int nVar1,int nVar2); 5 }</pre></pre>2. Implementation of the interfaceOnly classes and structs can implement interfaces, and interface names must be included in the base class list; the class or struct that uses the interface needs to provide an implementation for each member of the INTERFACE.<pre>1 Class Myclass:imyinterface2 {3 //the access modifier is set to public when the interface member is implicitly implemented4 public intMethod (intAintB)5 {6Console.WriteLine ("{0}", A +b);7 returnA +b;8 }9}</pre>If a class inherits the base class and implements the interface, the base class name in the base class list of the class must precede all the Interfaces. And a class can have only one base class, the other types listed must all be interface Names.An interface is not just a list of members that a class or struct implements, it is a reference type, and we cannot access the interface directly through the members of the class object, but we can obtain a reference to the interface by casting the class object reference to the interface Type. This allows us to invoke the method of the interface using the dot Number. Here the conversion is recommended with AS.<pre>1StaticvoidMain (string[] Args)2 {3 intA =5;4 intb =8;5MyClass MC =NewMyClass ();6 //how to invoke class object implementation7 Mc. Method (a, b);8 //converting a type to an interface type9IMyInterface MIF = MC asimyinterface;Ten Mif. Method (a, b); one}</pre>Output Results: 1313the benefit of using as for Casting: If a class implements an interface it returns an interface reference (safe) If the class does not implement an interface, it throws an exception, making it easy to find errors in a timely manner.3. Implement multiple interfacesA class or struct can implement any number of Interfaces.All implemented interfaces must be listed in the base class list and separated by Commas.If a class implements two interfaces with duplicate members (with the same signature and the same return type), when the class implements the interface member, the implementation can satisfy all interfaces that contain duplicate members at ONCE.<pre>1 InterfaceInterface1 {voidMethod (intAintb);}2 InterfaceInterface2 {voidMethod (intAintb);}3 //implement multiple interfaces separated by commas4 public classmyclass:interface1, Interface25 {6 /*7 * If the return type and parameters of the two interface member functions are identical,8 * Then we can do it once.9 */Ten public voidMethod (intAintB) one { aConsole.WriteLine ("{0}", A +b); - } -}</pre>If you want to deliberately detach the interface members of both interfaces, you need to create an explicit interface member member Implementation. Format: Interface name + dot delimiter + member function of the INTERFACE. Note: when the calling interface member is displayed, the default is public and no more access modifiers can be Added. <pre>1 InterfaceInterface1 {voidMethod (intAintb);}2 InterfaceInterface2 {voidMethod (intAintb);}3 //implement multiple interfaces separated by commas4 public classmyclass:interface1, Interface25 {6 //interface members that display the implementation Interface17 //already default to public, you cannot add an access modifier8 voidinterface1. Method (intAintB)9 {TenConsole.WriteLine ("{0}", A +b); one } a voidinterface2. Method (intAintB) - { -Console.WriteLine ("{0}", A +b); the } -}</pre>however, there is only an explicit interface member implementation, and there is no class-level implementation, so after instantiating the object of the class, it is not possible to point out the Method. If there is an explicit interface member implementation, the Class-level implementation is allowed, but is not required. and explicit interface member implementations are intelligently accessed through references to interfaces, even member functions within the class to access the members of the Interface.If a class implements an interface, its subclasses inherit the interface members of its base class implementation without having to implement it again.4. Inheritance of interfacesTo specify an interface to inherit from another interface, place the interface in a comma-delimited list of interfaces after the interface name in the interface Declaration. The same as the inheritance format of the class. however, Unlike classes, an interface can inherit any number of interfaces and can perform multiple inheritance. A sub-interface includes all interface members of all parent interfaces in addition to the interface that contains its own Declaration.5. Code Demo<pre>1 namespaceConsoleApplication22 {3 InterfaceIloveworld {voidSayHello ();}4 classcreature{}5 6 //when the base class and interface are implemented at the same time, the base class is placed at the front7 classPerson:creature,iloveworld8 {9 //an implicit declaration interface that can be accessed by both the object of the class and the object that can be converted to an interface referenceTen voidSayHello () one { aConsole.WriteLine ("Hello world!"); - } - //explicitly declares an interface member that can only be converted to an interface reference object to access the voidIloveworld.sayhello () - { -Console.WriteLine ("Hello world!"); - } + } - classcat:creature, Iloveworld + { a //relative to an explicit interface Implementation. Class-level interface implementations are not Required. at voidIloveworld.sayhello () - { -Console.WriteLine ("Miaomiaomiao"); - } - } - classdog:creature, Iloveworld in { - //cannot use public when explicitly invoking an interface member to voidIloveworld.sayhello () + { -Console.WriteLine ("Wangwangwang"); the } * } $ class programPanax Notoginseng { - Static voidMain (string[] Args) the { + //declares an array of creature acreature[] Pcreaturearray =Newcreature[3]; the //Here's The relationship between the object-oriented is-a that we learned last time . +pcreaturearray[0] =Newperson (); -pcreaturearray[1] =NewCat (); $pcreaturearray[2] =NewDog (); $ foreach(varCreatureinchPcreaturearray) - { - //using as for conversion theIloveworld B = Creature asiloveworld; - B.sayhello ();Wuyi } the Console.readkey (); - } wu } -}</pre>Interface DemoOperation Result:　　. NET Interface Learning Notes

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