如何在Java方法中将接口的实现作为变量传递？

Question

We have an interface Math .

We have two implementations of Math (say they are called Math1 and Math2 ). A small part of the project is being able to switch between the two.

In a class (say its called ClassName ) we were provided by our instructor, we have:

public static int evaluate(Math impl)

I have:

ClassName.evaluate(Math1);

It says it cannot find symbol. I tried putting it in quotes, but then that's a string. I've tried to google things to try, but I'm not finding anything that helps (maybe I'm just searching for the wrong thing). The files are in the same package.

How do I pass the interface implementation?

Answer 1

You are passing the class name instead of a class instance.

Try this:

// Evaluate with Math1.
Math m1 = new Math1();
ClassName.evaluate(m1);

// Evaluate with Math2.
Math m2 = new Math2();
ClassName.evaluate(m2);