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Does separation of interface from implementation within classes provide advantage?
Yes, it helps both the users and the maintainers of your class. Users are generally only interested the class interface (how to interact with the class), so by separating the implementation you do not distract the user with any unnecessary implementation details. Conversely, maintainers are more concerned with the implementation than the interface. By keeping the two separate, maintainers are much less likely to break any code that uses the class.
What else can I help you with?
What is the major difference in class and interface in c?
The implementation detail. Classes may provide a default implementation, interfaces provide only the method signatures
Which languages support multiple interface?
If by interface you mean, a mechanism to achieve abstraction and create a blueprint for future implementation. Java/C#/C++ all allow for multiple interfaces(abstract classes in C++) to be implemented.
When do you give preference to abstract classs and interface?
Abstract class provides a way of "being a [something like me]", or inheritance interface provides a set of functionality (contract) as "behaving". Abstract class provides the single inheritance and perhaps some default implementation, while interface may be implemented by different classes that have nothing to do one and other except the common interface implementation. The preference I would start with: Ask yourself that an object should be "Is a something or behave like something". If your answer is "Is a", then abstract class is more likely your good choice. But if your answer is behave like, does not need to Is a, then the interface is the way to go.
Interface in C plus plus?
Unless by "interface" you mean a user interface...C++ does not have interfaces per se, at least not in the same sense as, say, Java. In a C++ class, a function declared pure virtual makes the class non-instantiable and forces derived classes that want to be instantiable to provide an implementation. This has exactly the same effect as the interface concept of Java. So in C++, interface is just a synonym for abstract base class.
What is meant by interface of a class and implementation of a class in c plus plus?
The interface of a class is defined as being the methods that allow the outside world to interact with objects instantiated from that particular class type. That interface may be declared within the class itself or it may be inherited from base classes, or it may be some combination of the two. The interface may also be virtual or even pure-virtual, either in whole or in part. The implementation determines how that interface operates. Although the interface and the implementation go hand-in-hand they are treated separately because a derived class can override the generic interface exposed by the base class in order to provide a more specialised implementation of the base class interface, as well as provide new interfaces of its own. The generic interface needn't be virtual in order to be overridden, but it must be virtual in order to allow polymorphic behaviour. Where the base class cannot provide an implementation because it is intentionally abstract and therefore relies solely upon a derived implementation, it will provide a pure-virtual interface that absolutely must be implemented by all derivatives. If a class declares or inherits a pure-virtual interface with no implementation, that class automatically becomes abstract. Only classes that provide a complete implementation for all pure-virtual interfaces (including any generic implementations inherited from base classes derived from the base class), can actually be instantiated. When calling a base class method from a non-member function, one would rightly expect the implementation of the derived class to be executed. In order to achieve this, the generic interface must be virtual and the virtual table ensures the call is routed to the correct implementation. Without this, only the base class method can be called, which may result in unexpected behaviour in the derived class since the base class would be unaware of its specific behaviour. While it is possible to allow a base class to gain access to a derived class interface without exposing a virtual interface, this can only be done when the base class already knows exactly what type of derivative to expect. Knowing the type of its derivative allows the base class to make an explicit dynamic cast of itself in order to call the appropriate interface. But it cannot predict the future: if you derive a new class of object that it knowns nothing about, it cannot gain access to its specialised interface. Even dynamic casting is impossible without knowing what type of object to cast to. Virtual interfaces overcome this problem by ensuring that no matter what derivatives are created either now or in the future, the base class can access each of their specific implementations through just one generic interface, without the need for any dynamic casting (which is almost always a sign of poor design). When a base class interface is routed to a derived class implementation, that specific implementation has complete access to the derived class' interface. Thus interfaces that the base class doesn't even know exist can be implemented via calls through the base class' virtual interface which is the only interface the base class really needs to know anything about. To put it another way, all derivatives of the same base class can be treated just as if they were the base class itself, with a common, generic interface, and yet each instance can exhibit entirely different behaviour, according to the specific implementations defined by each derivative. That is, one interface/multiple implementations. Derived class implementations may also, optionally, call any base class method and access any base class variable (other than the base class' private members, of course). This makes it possible to provide a generic implementation of the virtual interface that can then be augmented or replaced completely by the more specific implementations of the derived interface. Even pure-virtual methods, which are normally not implemented in an abstract base class, can provide a generic implementation where appropriate. Although the implementation cannot be inherited, the interface must be inherited because it is virtual. However, once a derived class implements a pure-virtual interface, that implementation can then be inherited by its derivatives, to be further specialised and or augmented as necessary.
Explain advantage of bi- directional implementation with example?
Advantage of Bi-directional Implementation : 1. Bi directional implementation of association is useful for two way navigation between classes 2. Independent of Classes 2. Useful for existing predefined classes which are not modified.
What is bidirectional implementation what is advantage of bidirectional implementation with examples?
Advantage of Bi-directional Implementation 1. Bi directional implementation of association is useful for two way navigation between classes 2. Independent of Classes 2. Useful for existing predefined classes which are not modified.
What is the major difference in class and interface in c?
The implementation detail. Classes may provide a default implementation, interfaces provide only the method signatures
Which languages support multiple interface?
If by interface you mean, a mechanism to achieve abstraction and create a blueprint for future implementation. Java/C#/C++ all allow for multiple interfaces(abstract classes in C++) to be implemented.
When do you give preference to abstract classs and interface?
Abstract class provides a way of "being a [something like me]", or inheritance interface provides a set of functionality (contract) as "behaving". Abstract class provides the single inheritance and perhaps some default implementation, while interface may be implemented by different classes that have nothing to do one and other except the common interface implementation. The preference I would start with: Ask yourself that an object should be "Is a something or behave like something". If your answer is "Is a", then abstract class is more likely your good choice. But if your answer is behave like, does not need to Is a, then the interface is the way to go.
What are adapter classes in java?
An adapter class is a class that provides a dummy (empty) implementation for an interface. That way someone who wants to implement the interface but does not want or does not know how to implement all methods, can use the adapter class instead, and only override the methods he is interested in.
What is the interface and how will you go about implementing interface?
As defined in the java programming language 4th edition: The fundamental unit of programming in the Java programming language is the class, but the fundamental unit of object-oriented design is the type. While classes define types, it is very useful and powerful to be able to define a type without defining a class. Interfaces define types in an abstract form as a collection of methods or other types that form the contract for that type. Interfaces contain no implementation and you cannot create instances of an interface. Rather, classes can expand their own types by implementing one or more interfaces. An interface is an expression of pure design, whereas a class is a mix of design and implementation. ..... The idea behind this that an interface is just a "contract" where you can define methods a class will implement (better said (in OOP:) messages), but within the interface there are only signatures. No behavior for those methods... Then it class that implemets the interface will understand and provide an implementation for those methods (messages). So you can have a lot of diferents classes that implement the same interface and in any place you need that interface you can use any of those classes... that's one of the benefit of interfaces... e.g.: interface LifeBeing{ void breath(); } public class Human implements LifeBeing { void breath(){ // do something; } } public class Three implements LifeBeing { void breath(){ // do something else; } }
Interface in C plus plus?
Unless by "interface" you mean a user interface...C++ does not have interfaces per se, at least not in the same sense as, say, Java. In a C++ class, a function declared pure virtual makes the class non-instantiable and forces derived classes that want to be instantiable to provide an implementation. This has exactly the same effect as the interface concept of Java. So in C++, interface is just a synonym for abstract base class.
What is the use of interface in net?
Interfaces contain only the signatures or blueprint of methods, events or delegates and not the implementation. They're implemented in the class implementing the interface. They're used to specify a behavior common to all classes that implement them. The intricate details of how this behavor would be achieved is upto the discretion of the classes implementing them. Any class using them is bound to implement evrything specified in the interface. Hence one can be rest assured of this. They're good for data-hiding.
What is meant by interface of a class and implementation of a class in c plus plus?
The interface of a class is defined as being the methods that allow the outside world to interact with objects instantiated from that particular class type. That interface may be declared within the class itself or it may be inherited from base classes, or it may be some combination of the two. The interface may also be virtual or even pure-virtual, either in whole or in part. The implementation determines how that interface operates. Although the interface and the implementation go hand-in-hand they are treated separately because a derived class can override the generic interface exposed by the base class in order to provide a more specialised implementation of the base class interface, as well as provide new interfaces of its own. The generic interface needn't be virtual in order to be overridden, but it must be virtual in order to allow polymorphic behaviour. Where the base class cannot provide an implementation because it is intentionally abstract and therefore relies solely upon a derived implementation, it will provide a pure-virtual interface that absolutely must be implemented by all derivatives. If a class declares or inherits a pure-virtual interface with no implementation, that class automatically becomes abstract. Only classes that provide a complete implementation for all pure-virtual interfaces (including any generic implementations inherited from base classes derived from the base class), can actually be instantiated. When calling a base class method from a non-member function, one would rightly expect the implementation of the derived class to be executed. In order to achieve this, the generic interface must be virtual and the virtual table ensures the call is routed to the correct implementation. Without this, only the base class method can be called, which may result in unexpected behaviour in the derived class since the base class would be unaware of its specific behaviour. While it is possible to allow a base class to gain access to a derived class interface without exposing a virtual interface, this can only be done when the base class already knows exactly what type of derivative to expect. Knowing the type of its derivative allows the base class to make an explicit dynamic cast of itself in order to call the appropriate interface. But it cannot predict the future: if you derive a new class of object that it knowns nothing about, it cannot gain access to its specialised interface. Even dynamic casting is impossible without knowing what type of object to cast to. Virtual interfaces overcome this problem by ensuring that no matter what derivatives are created either now or in the future, the base class can access each of their specific implementations through just one generic interface, without the need for any dynamic casting (which is almost always a sign of poor design). When a base class interface is routed to a derived class implementation, that specific implementation has complete access to the derived class' interface. Thus interfaces that the base class doesn't even know exist can be implemented via calls through the base class' virtual interface which is the only interface the base class really needs to know anything about. To put it another way, all derivatives of the same base class can be treated just as if they were the base class itself, with a common, generic interface, and yet each instance can exhibit entirely different behaviour, according to the specific implementations defined by each derivative. That is, one interface/multiple implementations. Derived class implementations may also, optionally, call any base class method and access any base class variable (other than the base class' private members, of course). This makes it possible to provide a generic implementation of the virtual interface that can then be augmented or replaced completely by the more specific implementations of the derived interface. Even pure-virtual methods, which are normally not implemented in an abstract base class, can provide a generic implementation where appropriate. Although the implementation cannot be inherited, the interface must be inherited because it is virtual. However, once a derived class implements a pure-virtual interface, that implementation can then be inherited by its derivatives, to be further specialised and or augmented as necessary.
Why do you have only public static final variables in interfaces?
Because of the below reasons:Class implementations can change value of fields if they are not defined as final. Then they would become a part of the implementation. An interface is a pure specification without any implementation, hence they are final to prevent accidental modificationsIf they are static, then they belong to the interface, and not the object, nor the run-time type of the object.An interface provide a way for the client to interact with the object. If variables were not public, the implementing classes would not have access to them.Hence variables in interfaces are public static and final
How do you use an interface?
When you implement an interface, you're agreeing to adhere to the contract defined in the interface. That means you're agreeing to provide legal implementations for every method defined in the interface, and that anyone who knows what the interface methods look like can rest assured that they can invoke those methods on an instance of your implementing class. (Thy need not bother much about how you have implemented it. All they bother about is whether a method of the name mentioned in the interface is available or not) Now, you might stop me and ask, what if I implement an interface and opt not to write code for a method that I am supposed to? The answer is simple. The compiler wouldn't let you do that. You cannot successfully implement an interface without providing method implementation for all the methods declared inside the interface. This is how the java system ensures that when someone knows a certain method name in an interface and has an instance of a class that implements it, can actually call that method without fear that the method isn't implemented inside the class. Assuming an interface, Convertible, with two methods: openHood(), and setOpenHoodFactor(), the following class will compile: public class Ball implements Convertible { // Keyword 'implements' public void openHood() { } public void setOpenHoodFactor(int bf) { } } Ok, I know what you are thinking now. "This has got to be the worst implementation class that you have seen". Though it compiles and runs as well, it is actually doing nothing… the interface contract guarantees that the class implementing it will have a method of a particular name but it never guaranteed a good implementation. In other words, the compiler does not bother whether you have code inside your method or not. All it cares is if you have methods of the matching names as in the interface. That's all… Implementation classes must adhere to the same rules for method implementation as a class extending an abstract class. In order to be a legal implementation class, a nonabstract implementation class must do the following: • Provide concrete (nonabstract) implementations for all methods from the declared interface. • Follow all the rules for legal overrides. • Declare no checked exceptions on implementation methods other than those declared by the interface method, or subclasses of those declared by the interface method. • Maintain the signature of the interface method, and maintain the same return type (or a subtype). • It does not have to declare the exceptions declared in the interface method declaration
