当前两个已经处于基-子类关系中时，如何继承第三个类中的两个类？

Question

Say I want to inherit Class A and Class B to Class C, (here B extends A as well). I am very well aware that though I can never do it directly in Java, but by using Mixin inheritance (Link: http://csis.pace.edu/~bergin/patterns/multipleinheritance.html ) , that is use of one interface and other one as base class and internally using delegation I can do it, when A & B are unrelated class.

How do I do the same when A & B have parent child them selves, and I need to inherit both of them in C?

Just for your info, I am trying to do the same to achieve immutability in classes A & B.

Answer 1

If your class B already extends class A , then having class C extend class B would already do the trick. by extending class B you also get all functionality from class A that has not been specifically overridden in class B

Presumably you'd end up with:

class A
{
    public string hello()
    {
        return "Hello, World!";
    }
}

class B extends A
{
}

class C extends B
{
}

C foo = new C();
foo->hello(); // "Hello World!" because it is defined in A

Answer 2

为什么不将A类作为抽象类，然后将其扩展到B和C中呢？让您的通用方法作为A抽象体（或可以定义）位于A中，然后可以在具体类中覆盖它们。