在java中，一个类可以同时具有抽象性和具体性吗？

Question

Have a doubt :

Can a class be abstract and concrete at the same time in java? ie if an abstract class has no abstract methods in it, then can it be called a concrete class. Also can we say that any and every class that has no abstract method be called a concrete class?

Answer 1

The main difference lies in the documentation where it states:

An abstract class is a class that is declared abstract—it may or may not include abstract methods. Abstract classes cannot be instantiated, but they can be subclassed.

Instantiation is the key here.

Answer 2

The answers are "no" and "no". Abstract classes are only those that have been declared with the keyword abstract , whether or not they contain abstract methods. A non-abstract class is not allowed to contain abstract methods.