Why multiple inheritance is not possible in .net

Assume that B and C are overriding an inherited method and they provide their own implementation. Now D inherits from both B and C doing multiple inheritance. D should inherit that overridden method, jvm can't able to decide which overridden method will be used? This can be avoided by using interfaces, there are no method bodies. Interfaces cannot be instantiated—they can only be implemented by classes or extended by other interfaces.

Actually multiple inheritance will arise a the complexity if the inherited classes have same function. So in Java that complexity removed and gave interface to get the functionality like multiple inheritance gave. We can use interface. Java has concept, i. There are 2 types of polymorphism in java.

There are method overloading and method overriding. Among them, method overriding happens with super- and subclass relationship. If we are creating an object of a subclass and invoking the method of superclass, and if subclass extends more than one class, which super class method should be called? Or , while calling superclass constructor by super , which super class constructor will get called?

This decisions are impossible by current java API features. Interfaces : Interfaces are completely abstract classes in Java that provide you with a uniform way to properly delineate the structure or inner workings of your program from its publicly available interface, with the consequence being a greater amount of flexibility and reusable code as well as more control over how you create and interact with other classes.

More precisely, they are a special construct in Java with the additional characteristic that allow you to perform a kind of multiple inheritance i.

Suppose there are 2 superclasses classes A and B with same method names but different functionalities. Through following code with extends keyword multiple inheritance is not possible. You can find answer from this documentation link. One reason why the Java programming language does not permit you to extend more than one class is to avoid the issues of multiple inheritance of state, which is the ability to inherit fields from multiple classes.

If multiple inheritance is allowed and when you create an object by instantiating that class, that object will inherit fields from all of the class's super classes.

It will cause two issues. Multiple inheritance of type : Ability of a class to implement more than one interface.

Multiple inheritance of implementation through default methods in interfaces : Ability to inherit method definitions from multiple classes. Multiple Inheritance Ambiguity with Interface. C and Java, however, limit classes to single inheritance each class inherits from a single parent class. Multiple inheritance is a useful way to create classes that combine aspects of two disparate class hierarchies, something that often happens when using different class frameworks within a single application.

If two frameworks define their own base classes for exceptions, for example, you can use multiple inheritance to create exception classes that can be used with either framework. The problem with multiple inheritance is that it can lead to ambiguity. The classic example is when a class inherits from two other classes, each of which inherits from the same class:.

In this example, the flag data member is defined by class A. Which one do you want to set? The compiler will complain that the reference to flag in D is ambiguous.

One fix is to explicitly disambiguate the reference:. Another fix is to declare B and C as virtual base classes , which means that only one copy of A can exist in the hierarchy, eliminating any ambiguity.

Other complexities exist with multiple inheritance, such as the order in which the base classes are initialized when a derived object is constructed, or the way members can be inadvertently hidden from derived classes.

To avoid these complexities, some languages restrict themselves to the simpler single inheritance model. Although this does simplify inheritance considerably, it also limits its usefulness because only classes with a common ancestor can share behaviors. Now when I create object for Circle, and call the method, system does not know which calculate area method to be called. Both has same signatures. So compiler will get confuse. That's why multiple inheritances are not allowed.

But there can be multiple interfaces because interfaces do not have method definition. Even both the interfaces have same method, both of them do not have any implementation and always method in the child class will be executed. Stack Overflow for Teams — Collaborate and share knowledge with a private group. Create a free Team What is Teams? Collectives on Stack Overflow. Learn more. Why is Multiple Inheritance not allowed in Java or C?

Ask Question. Asked 12 years, 5 months ago. Active 3 years, 2 months ago. Viewed 82k times. Improve this question. Jon Schneider Abdulsattar Mohammed Abdulsattar Mohammed 9, 12 12 gold badges 49 49 silver badges 66 66 bronze badges. Just like to point out that there are frameworks out there which allow MI-like behavior in C classes. And of course you have the option of having stateless mixins using extensions methods - being stateless they are not very useful though. That interfaces have anything to do with inheritance is an illusion created by the language syntax.

Inheritance is supposed to make you richer. Nothing like that for an interface, you don't inherit squat and it makes you significantly poorer. You inherited uncle Harry's gambling debt, you have more work to do to implement the interface. Add a comment. Active Oldest Votes. The short answer is: because the language designers decided not to. For Java, you can read this article : The reasons for omitting multiple inheritance from the Java language mostly stem from the "simple, object oriented, and familiar" goal.

Improve this answer. Razzie Razzie Very nicely explained. Thank you, Suraj. Posted 7-Oct am Mukesh Pr sad. Multiple inheritance create tight coupling which make maintenance hard.

For extensibility and reuse purpose, it is better to that your main object contains sub-object. At that point you can easily change a sub-object for a derived one and support a lot of combination. When it make sense, you might even be able to change a sub-object at run time or decide which sub-object to uses at creation time.

This give a lot of flexibility. One problem with multiple inheritance is that once you use it a lot, you will find that you often have the wrong combination of parent classes and you have a lot of refactoring to adjust the class hierarchy or create similar classes that differs only from one or 2 bases classes among a few one. Say that you inherited from 3 classes and each of those have 3 subclasses. If you need all possibilities, you will have 4 x 4 x 4 possibilities for parents giving 64 combinations.

On the other hand, if those are sub-object, then you have a single class with 4 possible classes for each sub-object.

Also the parent class would have a lot of unctions and you might have to maintain around 70 to 80 classes if you change one virtual functions. In the other case, you'll have to change only 4 classes Posted 7-Oct pm Philippe Mori. Add your solution here. OK Paste as. Treat my content as plain text, not as HTML. Existing Members Sign in to your account.

This email is in use. Do you need your password? Submit your solution! When answering a question please: Read the question carefully.

Understand that English isn't everyone's first language so be lenient of bad spelling and grammar. If a question is poorly phrased then either ask for clarification, ignore it, or edit the question and fix the problem. Insults are not welcome. Don't tell someone to read the manual. Chances are they have and don't get it. Multiple inheritance does not get implemented in C because of Diamond drawback. If it is required to implement multiple inheritance in C then we use at least one Interface as base class.

Yes, it is due to the diamond problem. The diamond problem is an ambiguity that arises when two classes B and C inherit from A, and class D inherits from both B and C. Yes, due to diamond problem. Simply, it will increase the complexity the developer may difficult to find which method is from which class.

If multiple inheritance would have allowed in the C , there would be a problem so called "Diamond Problem". Diamond problem occurs when same method exist in two or more base classes. Thus the child class would end up inheriting duplicate methods. Multiple inheritance is not possible beacuse Multiple inheritance Suffer From Ambugity Problem,that means there can be chances that same method present in both the call.

Why multiple inheritance is not possible in c. By Rajesh Singh in. NET on Jul 09 Nov, 2. It causes the ambiguity error in C.