This question already has answers here:
Why is multiple inheritance not supported in most of programming language?
(3 answers)
Closed 9 years ago.
Yeah the title pretty much describes the question.
Are there any advantages to non allowing multiple inheritance in a programming language?
It removes the possibility of the so called "diamond problem" (http://en.wikipedia.org/wiki/Multiple_inheritance#The_diamond_problem) that can occur when a class inherits from two classes having different implementations of methods of the same name.
Java instead have interfaces. A class can implement any number of interfaces and you can use a reference of the interface type to refer to any object of a class that implements this interface. Interfaces does not contain implementations and cannot be instantiated.
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This question already has answers here:
Java doesn't support multiple inheritance but implicitly every class in java extends Object and allows one more [duplicate]
(8 answers)
Closed 2 years ago.
Every class is inherited from Object class and they will also extend some other parent class in inheritance why is it not considered as multiple inheritance.
It's because in Java you can directly inherit from only one parent class. We would consider multiple inheritance if you'd be able to extend from multiple classes but that's not a thing in Java.
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Why is there no multiple inheritance in Java, but implementing multiple interfaces is allowed?
(21 answers)
Closed 3 years ago.
Multiple inheritance is not supported in the case of class because of ambiguity. However, it is supported in case of an interface. why there is no ambiguity when it comes to implementation?
Its because interface just states what methods are there. We need to define how methods will work.
And even if you define a method it automatically becomes static(from java 1.8 on wards. defining method body is permitted in an interface).
In multiple inheritance, same function may be defined differently in both the parent class which results in conflict. Thus, Multiple inheritance is not supported.
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Java 9 Interface vs Class
(5 answers)
Closed 4 years ago.
With the addition of default methods in interfaces, what is the difference between abstract classes and interfaces?
The main difference between an abstract class and interface in Java 8 is the fact that an abstract class is a class and an interface is an interface.
A class can have a state which can be modified by non-abstract methods but an interface cannot have the state because they can't have instance variables.
The second difference is that an interface cannot have a constructor even in Java 8 but you may remember that abstract class always has a constructor in Java.
In reality, default or defender methods are introduced to maintain backward compatibility and same time making Collection API more suitable to be used inside key Java 8 features like lambda expressions.
Without adding default methods, it wasn't possible to declare any new method on existing interface in Java without breaking all classes which implement it, but because of default method, you can now better evolve your API.
They defend your code against implementing new methods hence they are also called defender methods.
Java 9 interfaces still cannot contain constructors.
Java 9 interfaces still cannot have non-static members.
these are big difference and not multiple inheritance IMO.
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Implementing Class Adapter Pattern in Java
(5 answers)
Closed 9 years ago.
Is it possible to implement class adapter pattern in Java?
I'm trying to read everything on the internet but still have found an example.
It is possible, but pure interfaces must be used instead of abstract classes, since Java does not support multiple inheritance.
There are two variations of the Adapter pattern: inheritance-based (a.k.a. class Adapter) and composition-based. The inheritance variation requires the use of multiple inheritance, which doesn't exist in Java and therefore it's impossible to implement. But of course, you can do the composition-based implementation, without any problems.
This question already has answers here:
Closed 11 years ago.
Possible Duplicate:
Interface vs Abstract Class (general OO)
I want to know the difference between an Interface and an Abstract class ?
I'm so confused about this.
Thanks already.
In an interface you simply define the methods that you are going to implement. In an abstract class you can actually write methods that contain some code. I'm sure this question has been asked a thousand times so look at some of the other posts.
Interfaces define contracts. Abstract classes provide for code reuse. An object interacts with other objects via their contracts (Interfaces). An object shares code with other, related, objects, by inheriting it from an abstract class.