The order in which subclasses override methods inherited from their parent class

When constructing an object, the system constructs the superclass object first, then the subclass object.

The order in which an object is constructed: (Note: this is also the order in which an object is constructed.)

① Construct the parent object recursively;

② Call the member attribute assignment statement of this class sequentially;

③ The construction method of this class.

Super() means to call the constructor of the parent class.

Super(), like this, must be placed in the first line.

This() is used to call the constructor of This class.

If no constructor is defined, the no-argument constructor of the parent class, super(), is called.