The difference between Java abstract class and ordinary class

1. Abstract classes cannot be instantiated.

2. Abstract classes can have constructors, which are inherited when the subclass must inherit a constructor of the parent class, and the abstract method cannot be declared static.

3. Abstract methods only need to declare, without implementation, the abstract class can allow the normal method has the principal

4. Classes that contain abstract methods must be declared as abstract classes

5. An abstract subclass must implement all abstract methods in an abstract class, or the subclass is an abstract class.

Can abstract classes have constructors? The answer is yes. The constructor of an abstract class is used to initialize some fields of an abstract class, all of which occur before the derived class of the abstract class is instantiated. Not only that, the constructor of the draw line class has a clever application: The code that implements the subclass must execute inside it

The difference between Java abstract class and ordinary class