#abstract class in java

An abstract class in Java is one that is intended to be subclassed by other classes and cannot be instantiated on its own. It can have concrete methods, abstract methods, or a mix of both; it acts as a model for other classes.

Abstract Keyword:

The abstract keyword is used to declare an abstract class. Abstract classes may have abstract methods (methods without a body) as well as concrete methods (methods with a body).

Abstract Methods:

Abstract classes can have abstract methods, which are declared without a body and are meant to be implemented by the subclasses.

Subclassing:

When you extend an abstract class, you must either provide concrete implementations for all the abstract methods in the subclass or declare the subclass as abstract.

Constructor:

Abstract classes can have constructors, and they are invoked when a subclass object is created. However, abstract classes cannot be instantiated directly.

Usage:

Abstract classes are useful when you want to provide a common interface or functionality that should be shared among multiple related classes.

Java: Type of Classes

Pre-Requisite: Java: Class In a previous post, you have got an understanding of java class declaration and creation.

Types of classes

Java supports lots of types of classes:

Concrete Class

Abstract Class

POJO Class

Static Class

Nested Class/Inner Class

Final Class

Anonymous Class

Lambda Expression

Here we will discuss these classes in detail.

Concrete Class

A concrete class is a normal class that…

Java: Abstract Class Vs Interface

Abstract class and interface in java used to provide abstraction but there are lots of differences:

Abstract Class Interface Abstraction(0 to 100%) Abstraction(100%) Abstract class implemented by keyword ‘extends‘ Interface implemented by using keyword ‘implements‘ Abstract class also can not be instantiated but can be invoked if the main() method exists. Interfaceis completely abstract…

Abstraction in Java

Abstraction is a concept to show only essential detail i.e hide internal detail and show functionality in simple terms. To achieve abstraction in Java, use abstract class or interface.

Example: In ATM we don’t know how internally work. In a Car don’t know about the internal mechanism.

Ways to achieve Abstraction

We can achieve abstraction in two ways:

Abstract class:abstractio…