Thing-in-Java(P57)

The answer is the primary twist in object-oriented programming: the
compiler cannot make a function call in the traditional sense. The
function call generated by a non-OOP compiler causes what is called early
binding, a term you may not have heard before because you’ve never
thought about it any other way. It means the compiler generates a call to a
specific function name, and the linker resolves this call to the absolute
address of the code to be executed. In OOP, the program cannot
determine the address of the code until run time, so some other scheme is
necessary when a message is sent to a generic object.

 

翻译：，

这个问题的答案也是面向对象编程最巧妙的设计：编译器不能确保一个函数以传统的方式被调用，这个函数被一个不是面向对象的编译器调用会引起所谓的早期绑定，这个术语你也许从来没听过，因为你没有想过函数调用的其他方式。这意味着它创建一个特定的函数名的调用，这个连接到绝对的代码地址从而执行。在面向对象编程中，直到运行时才能确定那段代码的地址，所以当一个信息发送给一般的对象，采用其他的方式是必须的。