What is concrete class A?
A concrete class is a class that has an implementation for all of its methods. They cannot have any unimplemented methods. It can also extend an abstract class or implement an interface as long as it implements all their methods. In other words, we can say that any class which is not abstract is a concrete class.
What is concrete type in Java?
A concrete class is any normal class in a Java program. This class will not have any abstract methods. All the methods in the concrete class are completely implemented. A concrete class can inherit from another class, even an abstract class or implement an interface.
Is HashMap a concrete class?
HashMap and TreeMap are two of the concrete classes that implement the Map interface.
What is a concrete type?
In programming languages, an abstract type is a type in a nominative type system that cannot be instantiated directly; a type that is not abstract – which can be instantiated – is called a concrete type. An abstract type may provide no implementation, or an incomplete implementation.
What is a concrete sub class?
A concrete class is a subclass of an abstract class, which implements all its abstract method. If a class extends an abstract class, then it should define all the abstract methods (override) of the base abstract class. If not, the subclass(the class extending abstract class) must also be defined as abstract class.
What is Java API example?
1. Java API. An API stands for Application Programming Interface, and it is an interface that allows communication between different applications using the packages it comprises. For example, we use JDBC API in java to connect to any database server to perform several transactions using java.
What API means Java?
Application Programming Interface
The full form of API is Application Programming Interface. It is a document which gives you the list of all the packages, classes, and interfaces, along with their fields and methods.
Is interface a concrete class?
Interfaces cannot be instantiated as they are not concrete classes.
Which class in Java contains concrete and non concrete method?
A class that is declared using “abstract” keyword is known as abstract class. It can have abstract methods(methods without body) as well as concrete methods (regular methods with body).
What is concrete class and abstract class?
Difference between Abstract Class and Concrete Class in Java
| Abstract Class | Concrete Class |
|---|---|
| An abstract class may or may not contain abstract methods. | A concrete class cannot contain an abstract method. |
| An abstract class cannot be declared as final. | A concrete class can be declared as final. |