Java对多重继承的怀疑

Question

Java does not support multiple inheritance but Object class is by default super class of all classes. eg

class Object
{

}
class B
{

}
class A extends B
{
}

Class A can access all method of B and Object.Is not it a example of multiple inheritance? So is it correct that Java does not support multiple inheritance.

---

my question is not to find difference between multilevel and multiple inheritance. Java Docs,it self says :Class Object is the root of the class hierarchy. Every class has Object as a super class. All objects, including arrays, implement the methods of this class. So it means Class Object is super class of Class A{Previous example}. But Class B is also Super Class of Class A. SO what is meaning of it ?

Answer 1

它被称为继承的 transitive 性质 。

Answer 2

Look at the difference between transitive inheritance ( C inherits directly from B and transitively from A ):

and multiple inheritance ( C inheriting from both A and B ):

Answer 3

No it isn't. Multiple inheritance is when a class has more than one direct base class, as in:

class A {}

class B {}

// not valid Java
class C extends A, B {}

A class may have many indirect base classes, each with only one direct base class, as in:

class D extends A {}

class E extends D {}

class F extends E {}

Here the inheritance hierarchy is F -> E -> D -> A -> Object, but this is still single inheritance.

Answer 4

Since no Java class can extend directly two or more classes you can safely say that Java does not support multiple inheritance.

You would have multiple inheritance if you were able to say class A extends B, C , but you can never do that.