Java interface forced type conversion note

1. The interface can be used to hold any implementation interface object, which is the same as that of the parent class.

2. Any method that requires a class A, you can use the subclass of A as a substitute for a. Of course, you need to take care of the problems caused by specific method coverage.

3. Once the forced conversion is successful, you can use any method of the converted object. For example:

> A = (a) B // converts B to an instance of object.

> A. methodofa () // although it is B, but you tell the compiler that I want to use it as a, the method that belongs to a can naturally be called.

Note: whether the conversion is successful does not fall under the jurisdiction of the compiler. an inappropriate type will give you an exception during runtime.