What is the Concrete class in java

A concrete class is a class that has an implementation for all of its methods that were inherited from abstract or implemented via interfaces. It also does not define any abstract methods of its own. This means that an instance of the class can be created/allocated with the new keyword without having to implement any methods first. Therefore it can be inferred that any class that is not an abstract class or interface is a concrete class.

In your code above, C will be a concrete class as it implements all abstract methods inherited from A and implemented from B. Also, it does not define any abstract methods of its own.

As per name suggests, concrete means Solid, it means having no any row part or unimplemented things(methods).So we can conclude that concrete classes are those classes that can be instantiated with new key word. MyClass myClass = new MyClass();

A concrete class in Java is any such class which has implementation of all of its inherited members either from interface or abstract class

The simplest definition of a concrete class is that it's a class that is not abstract.