Java basics -- abstract classes and Abstract Functions, java --
- Abstract class
- Abstract classes cannot create objects, but can define variables. The objects assigned to this variable must be non-Abstract subclass objects;
- Abstract Functions in abstract classes do not have function bodies, such as: public abstract void move ();
- An abstract class can have no abstract methods. All methods have method bodies, but the entire class is abstract.
- All Abstract Functions in an abstract class must be overwritten by sub-classes instead of abstract functions. The subclass inherits the functions of the parent class. If the inherited abstract functions are not overwritten, The subclass contains Abstract Functions. Classes containing abstract functions must be declared as abstract classes.
- This abstract class is designed to prevent the creation of its objects.
