The difference between a class, an abstract class, and an interface

Only single inheritance between classes and classes

There can be many implementations between the class and the interface;

Multiple inheritance between interface and interface;

	Statement	Variable	Method	Relationships with interfaces	Relationships with classes	Whether the object can be constructed
Class	Using the Class keyword declaration, the modifier is public	Can be declared in any lawful manner	Can be declared in any lawful manner	Multi-Implementation	Single inheritance	objects can be constructed directly
Abstract class	Using the abstract class keyword declaration, the modifier is public	Can be declared in any lawful manner	If an abstract class contains abstract methods, then the declaration of this method must be abstract. This method cannot access permissions to private, cannot use the final decoration method, cannot be decorated with static, and the abstract method has no method body. There can be no abstract method in an abstract class	Multi-Implementation	Single inheritance	The object cannot be constructed directly, and if you want to construct it, you must inherit from the subclass and then construct
Interface	Using the interface keyword declaration, the modifier is public	The variables in the interface must be public static final, and this qualification is the default.	The method declaration in the interface must be public abstract, which is the default. The methods defined in the interface are all abstract methods.	Multiple inheritance	Multi-Implementation	Objects cannot be constructed directly, and if they are to be constructed, they must be implemented by subclasses and then constructed

The difference between a class, an abstract class, and an interface